WO2026024445A1

WO2026024445A1 - Power amplifier circuit with a dynamic range

Info

Publication number: WO2026024445A1
Application number: PCT/US2025/036310
Authority: WO
Inventors: Johannes STEIGERT; Alexander Schwarz
Original assignee: Outdoor Wireless Networks LLC
Current assignee: Outdoor Wireless Networks LLC
Priority date: 2024-07-24
Filing date: 2025-07-02
Publication date: 2026-01-29
Anticipated expiration: 2027-01-24

Abstract

A power amplifier circuit having a dynamic range is provided that includes a power amplifier with a transistor, a bias control, a power detector, a temperature sensor, a controller and a memory. The bias control is coupled to control a bias gate voltage of the transistor. The power detector is in a feedback loop that is coupled to an output of the power amplifier. The temperature sensor is positioned to measure a temperature related to the power amplifier. The controller is configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector. The memory is in communication with the controller and is used to store at least operating instructions implemented by the controller and the lookup table.

Description

POWER AMPLIFIER CIRCUIT WITH A DYNAMIC RANGE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims priority to U.S. Provisional Application Serial No. 63/675.071, same title herewith, filed on July 24, 2024. which is incorporated in its entirety herein by reference.

BACKGROUND

[0002] Requirements for power amplifiers in communication systems have changed over the past decades. Previously the focus was on the linearity of amplifier stages. New concepts, such as digital predistortion, have required designers to compromise between linearity and other parameters. Further, efficiency and power consumption have become important for mobile operators in wireless communication systems due to rising energy’ costs and a growing global focus on environmental sustainability.

[0003] Modem wireless communication systems, such as Long-Term Evolution (LTE) and fifth generation New Radio (5G NR), are typically deployed using different frequency bands that need to handle high peak-to-average ratio (PAR) signals of up to 13 dB. For this reason, gain stages are ty pically operated at a backoff point from their saturation point, which results in a significant reduction in the overall efficiency in power amplifiers used in wireless communication systems. Modulated signals may require a high PAR during normal operation, whether or not there is traffic data (mobile/user communications) present within an associated communication cell. During periods of no traffic data, a power amplifier still has to transmit idle mode transmit (Tx) signals, such as reference signals. PBCH. and PDCCH signals for synchronization purposes, as typically there are no resource blocks allocated. For example, a fully loaded standard 5G NR test signal having a bandwidth of 40 MHz with traffic data in the associated communication cell, which may be used for a medium power system, results in approximately 35 dBm output power. In contrast, the same signal with no user/ data traffic present within the communication cell, results in average output power levels of about 13 dBm. In this example, a 22 dB dynamic range is required for the system. [0004] The architecture needed to accommodate a large dynamic range, such as the 22dB dynamic range discussed above, is difficult to achieve. A tradeoff must typically be made between linearity, power consumption (i.e. direct current (DC) consumption), acceptable error vector magnitude (EVM), as well as acceptable signal quality. Further, driving a power amplifier by an idle mode signal does not represent power amplifier operation in a nominal region, hence wireless network communication operators can suffer from low efficiency, a relatively high DC power consumption as well as other non-linearities based on the powder amplifier transient characteristics. In addition, it is desired that modem power amplifiers be designed to cope with different operation modes scenarios such as nominal power, idle mode with no traffic, reduced output power due to cell size reduction or reduced resource block allocations, and time division duplex (TDD) use cases with different download (DL) and upload (UL) ratios.

[0005] For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved broadband power amplifier.

SUMMARY

[0006] The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the subject matter described. Embodiments provide a broadband power amplifier with transient operating point adaptation.

[0007] In one embodiment, a power amplifier circuit having a dynamic range is provided. The power amplifier circuit includes a power amplifier that includes a transistor, a bias control, a power detector, a temperature sensor, a controller and a memory. The bias control is coupled to control a bias gate voltage of the transistor. The power detector is in a feedback loop that is coupled to an output of the power amplifier. The temperature sensor is positioned to measure a temperature related to the power amplifier. The controller is coupled to control the bias control. The controller is further in communication with the power detector in the feedback loop and the temperature sensor. The controller is configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current pow er signal from the power detector. The memory is in communication with the controller and is used to store at least operating instructions implemented by the controller and the lookup table.

[0008] In another embodiment, a communication system is provided. The communication system includes at least one base station, at least one remote antenna unit, and at least one master unit. The at least one base station is in communication with at least one wireless network communication operator. The at least one remote antenna unit is configured to wirelessly communicate with mobile devices. At least one remote unit of the at least one remote unit includes a power amplifier circuit having a dynamic range. The power amplifier circuit includes a power amplifier with a transistor, a bias control, a power detector, a temperature sensor, a controller and a memory. The bias control is coupled to control a bias gate voltage of the transistor of the power amplifier. The power detector that is in a feedback loop is coupled to an output of the power amplifier. The temperature sensor is positioned to measure a temperature related to the power amplifier. The controller is coupled to control the bias control. The controller is further in communication with the power detector in the feedback loop and the temperature sensor. The controller is configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector. The memory' is in communication with the controller to store at least operating instructions implemented by the controller and the lookup table. The at least one master unit is configured to interface communications between the at least one base station and the at least one remote antenna unit.

[0009] In still another embodiment, a method of operating a power amplifier in a communication system. The method includes periodically measuring a power level of an output signal of the power amplifier with a power detector; periodically measuring a temperature relating to the power amplifier with a temperature sensor; determining an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and a then current measured temperature of the pow er amplifier; and adjusting a bias gate voltage of a transistor of the power amplifier based on the determined operating point. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention can be more easily understood and further advantages and uses thereof will be more readily apparent, when considered in view of the detailed description and the following figures in which:

[0011] Figure 1 is a block diagram of a radio access network communication system that includes remote antenna units with power amplifier circuits with a dynamic range according to an example aspect of the present invention.

[0012] Figure 2 is a block diagram of a power amplifier circuit with a dynamic range according to an example aspect of the present invention.

[0013] Figure 3 illustrates a power amplifier dynamic operating point control flow diagram according to an example aspect of the present invention.

[0014] Figure 4 illustrates a change in current verses change in relative bias gate voltage graph.

[0015] Figure 5 illustrates a relative bias gate voltage verses temperature verses power graph.

[0016] Figure 6 illustrates a power gain verses input power graph.

[0017] In accordance with common practice, the various described features are not drawn to scale but are draw n to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.

DETAILED DESCRIPTION

[0018] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. The follow ing detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof. [0019] Embodiments of the present invention provide a broadband power amplifier circuit with an enhanced dynamic range. Examples of the power amplifier circuit are designed to be used in communication systems to efficiently deal with different operating scenarios such as nominal power, idle mode with no traffic, reduced output power due to cell size reduction or reduced resource block allocations, and time division duplex (TDD) use cases with different download (DL) and upload (UL) ratios.

[0020] Examples of the power amplifier circuit use a transient operating point adaptation. The transient operating point adaptation provides improved signal quality and lower current consumption in communication systems with data traffic fluctuations (high data traffic as well as low or sporadic data traffic). A transistor bias voltage adaptation function is used in some examples to dynamically adjust a gate volage of a power amplifier for the transient operating point adaption. The bias gate voltage of the power transistor is dynamically adjusted based on measured power and temperature by the bias voltage adaption function to improve efficiency and power consumption in a communication system. Improved power consumption in embodiments over a ty pical power amplifier used in a frequency division duplexing (FDD) application may reach up to 25 percent and in a time division duplexing (TDD) application may reach up to 75 percent with embodiments of the power amplifier circuit described herein. Further, embodiments provide a higher signal quality⁷ dynamic range, an ease of implementation in a pay-to-use service, low implementation costs, and potential field upgrade of existing products.

[0021] As described herein the terms "‘coupled to"’ includes components that are directly coupled to each other (in direct communication with) and components that may be in communication with each other through other intermediate components, switches, connections, etc. Similarly, the terms “in communication with” includes components that are both in direct communication with other components and components that are in indirect communication with other components (i.e.. through intermediate components).

[0022] Figure 1 is a block diagram illustrating one exemplary embodiment of a radio access network (RAN) communication system, such as a distributed antenna system (DAS) 100 in which a power amplifier circuits with a dynamic range may be implemented. In the example of Figure 4, the DAS 100 includes one or more master units 102 (also referred to as “host units” or “central area nodes” or “central units”) and one or more remote antenna units 104 (also referred to as “remote units” or “radiating points”) that are communicatively coupled to the one or more master units 102. In the Example of Figure 1, the DAS 100 comprises a digital DAS, in which DAS traffic is distributed between the master units 102 and the remote antenna units 104 in digital form. The DAS 100 can be deployed at a site to provide wireless coverage and capacity for one or more wireless network communication operators. The site may be, for example, a building or campus or other grouping of buildings (used, for example, by one or more businesses, governments, or other enterprise entities) or some other public venue (such as a hotel, resort, amusement park, hospital, shopping center, airport, university campus, arena, or an outdoor area such as a ski area, stadium or a densely- populated downtown area).

[0023] Each master unit 102 is communicatively coupled to at least one base station 106. One or more of the base stations 106 can be co-located with the respective master unit 102 to which it is coupled (for example, where the base station 106 is dedicated to providing base station capacity to the DAS 100). Also, one or more of the base stations 106 can be located remotely from the respective master unit 102 to which it is coupled (for example, where the base station 106 is a macro base station providing base station capacity to a macro cell in addition to providing capacity to the DAS 100). In this latter case, a master unit 102 can be coupled to a donor antenna using an over-the-air repeater in order to wirelessly communicate with the remotely located base station.

[0024] The base stations 106 may be implemented in a traditional manner in which a base band unit (BBU) is deployed at the same location with a remote radio head (RRH) to which it is coupled, where the BBU and RRH are coupled to each other using optical fibers over which front haul data is communicated as streams of digital IQ samples (for example, in a format that complies with one of the Common Public Radio Interface (CPRI), Open Base Station Architecture Initiative (OBSAI), and Open RAN (O-RAN) families of specifications). Also, the base stations 106 may be implemented in other ways (for example, using a centralized radio access network (C-RAN) topology where multiple BBUs are deployed together in a central location, where each of BBU is coupled to one or more RRHs that are deployed in the area in which wireless service is to be provided. Also, the base station 106 can be implemented as a small cell base station in which the BBU and RRH functions are deployed together in a single package. The base stations 106 communicate with the wireless network communication operators.

[0025] Master unit 102 may be configured to use wideband interfaces or narrowband interfaces to the base stations 106. Also, the master unit 102 may be configured to interface with the base stations 106 using analog radio frequency (RF) interfaces or digital interfaces (for example, using a CPRI, OBSAI, or O-RAN digital interface). In some examples, the master unit 102 interfaces with the base stations 106 via one or more wireless interface nodes (not shown). A wireless interface node can be located, for example, at a base station hotel, and group a particular part of a RF installation to transfer to the master unit 102.

[0026] Traditionally, a master unit 102 interfaces with one or more base stations 106 using the analog radio frequency signals that each base station 106 communicates to and from a mobile device 120 (also referred to as “mobile units” or “user equipment”) of a user using a suitable air interface standard. Although the devices 120 are referred to here as “mobile” devices 120, it is to be understood that the mobile devices 120 need not be mobile in ordinary use (for example, where the mobile device 120 is integrated into, or is coupled to, a sensor unit that is deployed in a fixed location and that periodically wirelessly communicates with a gateway or other device). The DAS 100 operates as a distributed repeater for such radio frequency signals. RF signals transmitted from each base station 106 (also referred to herein as “downlink RF signals”) are received at the master unit. In such examples, the master unit 102 uses the downlink RF signals to generate a downlink transport signal that is distributed to one or more of the remote antenna units 104. Each such remote antenna unit 104 receives the downlink transport signal and reconstructs a version of the downlink RF signals based on the downlink transport signal and causes the reconstructed downlink RF signals to be radiated from an antenna 114 coupled to or included in that remote antenna unit 104.

[0027] In some examples the master unit 102 is directly coupled to the remote antenna units 104. In one such example, the master unit 102 is coupled to the remote antenna units 104 using cables 121. For example, cables 121 can include optical fiber or Ethernet cable complying with the Category 5, Category 5e, Category 6, Category 6A, or Category 7 specifications. Future communication medium specifications used for Ethernet signals are also within the scope of the present disclosure. [0028] A similar process can be performed in the uplink direction. RF signals transmitted from mobile devices 120 (also referred to herein as ’‘uplink RF signals”) are received at one or more remote antenna units 104 via an antenna 114. Each remote antenna unit 104 uses the uplink RF signals to generate an uplink transport signal that is transmitted from the remote antenna unit 104 to a master unit 102. The master unit 102 receives uplink transport signals transmitted from one or more remote antenna units 104 coupled to it. The master unit 102 can combine data or signals communicated via the uplink transport signals from multiple remote antenna units 104 (for example, where the DAS 100 is implemented as a digital DAS, by digitally summing corresponding digital samples received from the various remote antenna units 104) and generates uplink RF signals from the combined data or signals. In such examples, the master unit 102 communicates the generated uplink RF signals to one or more base stations 106. In this way, the coverage of the base stations 106 can be expanded using the DAS 100.

[0029] As noted above, in the example shown in Figure 1, the DAS 100 is implemented as a digital DAS. In some examples of a “digital” DAS, real digital signals are communicated between the master unit 102 and the remote antenna units 104. In some examples of a “digital” DAS, signals received from and provided to the base stations 106 and mobile devices 120 are used to produce digital in-phase (I) and quadrature (Q) samples, which are communicated between the master unit 102 and remote antenna units 104. It is important to note that this digital IQ representation of the original signals received from the base stations 106 and from the mobile units still maintains the original modulation (that is, the change in the instantaneous amplitude, phase, or frequency of a carrier) used to convey telephony or data information pursuant to the cellular air interface standard used for wirelessly communicating between the base stations 106 and the mobile units. Examples of such cellular air interface standards include, for example, the Global System for Mobile Communication (GSM), Universal Mobile Telecommunications System (UMTS), High- Speed Downlink Packet Access (HSDPA), Long-Term Evolution (LTE), Citizens Broadband Radio Service (CBRS), and fifth generation New Radio (5GNR) air interface standards. Also, each stream of digital IQ samples represents or includes a portion of the frequency spectrum. For example, the digital IQ samples can represent a single radio access network carrier (for example, a 5G NR carrier with 40 MHz or 400 MHz signal bandwddth) onto which voice or data information has been modulated using a 5G NR air interface. It is to be understood that each such stream can also represent multiple carriers (for example, in a band of the frequency spectrum or a sub-band of a given band of the frequency spectrum). A 5G NR carrier can have a maximum signal bandwidth of 100MHz for FR1. A bandwidth of 400 MHz can be achieved with 4 times 100MHz carriers, for example.

[0030] In the example shown in Figure 1, the master unit 102 can be configured to interface with one or more base stations 106 using an analog RF interface (for example, via an analog RF interface of an RRH or a small cell base station). In some examples, the base stations 106 can be coupled to the master unit 102 using a network of attenuators, combiners, splitters, amplifiers, filters, cross-connects, etc., which is referred to collectively as a point- of-interface (POI) 107. This is done so that, in the downlink, the desired set of RF carriers output by the base stations 106 can be extracted, combined, and routed to the appropriate master unit 102, and so that, in the uplink, the desired set of carriers output by the master unit 102 can be extracted, combined, and routed to the appropriate interface of each base station 106. In other examples, the POI 107 can be part of the master unit 102.

[0031] In the example shown in Figure 1, in the downlink, the master unit 102 can produce digital IQ samples from an analog signal received at certain radio frequencies. These digital IQ samples can also be filtered, amplified, attenuated, and/or re-sampled or decimated to a lower sample rate. The digital samples can be produced in other ways. Each stream of digital IQ samples represents a portion of the frequency spectrum output by one or more base stations 106.

[0032] Likewise, in the uplink, the master unit 102 can produce an uplink analog signal from one or more streams of digital IQ samples received from one or more remote antenna units 104 by digitally combining streams of digital IQ samples that represent the same carriers or frequency bands or sub-bands received from multiple remote antenna units 104 (for example, by digitally summing corresponding digital IQ samples from the various remote antenna units 104). performing a digital-to-analog process on the real samples in order to produce an IF or baseband analog signal, and up-converting the IF or baseband analog signal to the desired RF frequency. The digital IQ samples can also be filtered, amplified, attenuated, and/or re-sampled or interpolated to a higher sample rate, before and/or after being combined. [0033] In the example shown in Figure 1, the master unit 102 can be configured to interface with one or more base stations 106 using a digital interface (in addition to, or instead of) interfacing with one or more base stations 106 via an analog RF interface. For example, the master unit 102 can be configured to interact directly with one or more BBUs using the digital IQ interface that is used for communicating between the BBUs and an RRHs (for example, using the CPRI serial digital IQ interface).

[0034] In the downlink, the master unit 102 terminates one or more downlink streams of digital IQ samples provided to it from one or more BBUs and, if necessary, converts (by resampling, synchronizing, combining, separating, gain adjusting, etc.) them into downlink streams of digital IQ samples compatible with the remote antenna units 104 used in the DAS 100. In the uplink, the master unit 102 receives uplink streams of digital IQ samples from one or more remote antenna units 104, digitally combining streams of digital IQ samples that represent the same carriers or frequency bands or sub-bands received from multiple remote antenna units 104 (for example, by digitally summing corresponding digital IQ samples received from the various remote antenna units 104), and. if necessary, converts (by resampling, synchronizing, combining, separating, gain adjusting, etc.) them into uplink streams of digital IQ samples compatible with the one or more BBUs that are coupled to that master unit 102.

[0035] In the downlink, each remote antenna unit 104 receives streams of digital IQ samples from the master unit 102, where each stream of digital IQ samples represents a portion of the radio frequency spectrum output by one or more base stations 106. Each remote antenna unit 104 generates, from the downlink digital IQ samples, one or more downlink RF signals for radiation from the one or more antennas coupled to that remote antenna unit 104 for reception by any mobile devices 120 in the associated coverage area. In the uplink, each remote antenna unit 104 receives one or more uplink radio frequency signals transmitted from any mobile devices 120 in the associated coverage area, generates one or more uplink streams of digital IQ samples derived from the received one or more uplink radio frequency signals, and transmits them to the master unit 102.

[0036] Each remote antenna unit 104 can be communicatively coupled directly to one or more master units 102 or indirectly via one or more other remote antenna units 104 and/or via one or more intermediate units 116 (also referred to as “expansion units’" or “transport expansion nodes”). The later approach can be done, for example, in order to increase the number of remote antenna units 104 that a single master unit 102 can feed, to increase the master-unit-to-remote-antenna-unit distance, and/or to reduce the amount of cabling needed to couple a master unit 102 to its associated remote antenna units 104. The expansion units are coupled to the master unit 102 via one or more cables 121.

[0037] In the example DAS 100 shown in Figure 1, a remote antenna unit 104 is shown having another co-located remote antenna unit 105 (also referred to herein as an ‘"extension unit”) communicatively coupled to it. Subtending a co-located extension remote antenna unit 105 from another remote antenna unit 104 can be done in order to expand the number of frequency bands that are radiated from that same location and/or to support MIMO service (for example, where different co-located remote antenna units radiate and receive different MIMO streams for a single MIMO frequency band). The remote antenna unit 104 is communicatively coupled to the “extension” remote antenna units 105 using a fiber optic cable, a multi-conductor cable, coaxial cable, or the like. In such an implementation, the remote antenna units 105 are coupled to the master unit 102 of the DAS 100 via the remote antenna unit 104.

[0038] One or more of the remote units 104 includes a power amplifier circuit 200 with a dynamic range. The power amplifier circuit 200 provides a broadband power amplifier with transient operating point adaptation. The amplifier circuit 200 with the transient operating point adaptation provides improved signal quality and lower current consumption of communication systems with strong data traffic fluctuation, and low or sporadic data traffic.

[0039] An example of a power amplifier (PA) circuit 200 of an embodiment is illustrated in Figure 2. The PA circuit 200 includes a processing unit, or controller 202, memory 204, and a front end 205 with a high-power transistor 226.

[0040] In general, the controller 202 may include any one or more of a processor, microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field program gate array (FPGA), or equivalent discrete or integrated logic circuitry. In some example embodiments, controller 202 may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions atributed to controller 202 herein may be embodied as software, firmware, hardware or any combination thereof. Controller 202 may be part of a system controller or a component controller. Memory 204 may include computer-readable operating instructions that, when executed by controller 202 provides functions of the dynamic PA circuit 200. Such functions may include the transistor bias voltage adaptation function described below. The computer readable instructions may be encoded within memory 204. Memory 204 is an appropriate non-transitory storage medium or media including any volatile, nonvolatile, magnetic, optical, or electrical media, such as, but not limited to, a random-access memory (RAM), read-only memory' (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory’, or any other storage medium.

[0041] Memory 204 includes a lookup table 206. Lookup table 206 includes temperature verses power verses bias voltages. Controller 202, in communication with memory 204, selects a gate bias voltage (gate voltage) based on an input from a temperature sensor 210 and an input from a power detector 248 using the lookup table 206. The temperature sensor 210 is placed near a power amplifier 222. Controller 202 directs a bias voltage controller 232 to provide a select bias gate voltage to high-power-transistor 226 based on a then cunent operating point found in lookup table 206 in memory 204.

[0042] The front end 205 further includes a radio transceiver 208 and the poyver amplifier 222. Radio transceiver 208 includes a transmitter output 212. The transmitter output 212 is coupled to a first port of circulator 218 in one example. Circulator 218 includes a second port that is coupled to an input of a driver 221 and a third port that is coupled to a termination 220. In another example, a circulator is not positioned between the transmitter output 112 and the input of the driver 221 . An output of the driver 221 is coupled to an input of a splitter 224 of the power amplifier 222. Another input to splitter 224 is coupled to termination 230.

Transistor 226. in this example, is a dual-path transistor. A pair of outputs of the splitter 224 are coupled to a pair of inputs to transistor 226. A pair of outputs of transistor 226 are coupled to a Doherty output combiner (OC) 228. In one example the power amplifier 222 uses a dual-input Doherty transistor in a digital pre-distortion (DPD) system. In other examples, another type of PA is used that has a PA architecture that has one or more bias gate voltages. [0043] An output of the OC 228 is coupled to a directional coupler (DC) 234. A first output of the DC 234 is coupled to a first port of circulator 236. A second port of the circulator 236 is coupled to an output 238 of the power amplifier circuit 200. A third output of the circulator 236 is coupled to a time division duplex (TDD) switch 240. In an alternative example, an isolator is sufficient for frequency division duplex (FDD) use cases with an Rx coupling via duplexer. One pole of the TDD switch is coupled to a termination 242 and the other pole of TDD switch 240 is coupled to a receiver input 214 through a low noise amplifier (LNA) amplifier 244. The TDD switch 240 is used to time the transmission and receiving of the TDD system.

[0044] PA circuit 200 further includes a closed feedback loop 260. The closed feedback loop 260 includes a splitter 246. The splitter 246 includes a first input that is coupled to an output of directional coupler 234. A digital predistortion (DPD) feedback 216 is coupled to a port of the splitter 246. A termination 250 is coupled to another port of the splitter. A power detector (PD) 248 is coupled to an output port of the splitter 246. PD 248 is coupled to provide a PD signal to the controller 202. In embodiments, the dynamic operating point adaptation is regulated by the closed feedback loop 260. Further in an example where the radio transceiver 208 supports DPD, the radio transceiver 208 may also contain a power detector whose power information can be forwarded on to controller 202. In this example, PD 248 may be the power detector from the radio transceiver.

[0045] The approach discussed above with the PA circuit 200 is not dependent on a transceiver chip. Further, the approach may be used with a single PA without linearization in an embodiment. Possible applications include operation at nominal power, idle mode with no traffic, reduced output power due to cell size reduction or reduced resource block allocations, and TDD use cases with different DL and UL ratios.

[0046] An example PA circuit 200 and/or associated communication system, such as DAS discussed above, may support operations where the PA circuit 200 is operated under full load (i.e. a very large number of subscribers are served by a communication cell of the DAS during most of the operation). Under the full load, a standard "nominal operation" is sufficient, and the operator can use the system as usual. The PA circuit 200 also supports operation where user traffic fluctuates greatly, or the PA circuit 200 is hardly used. In this case, a wireless network communication operator could purchase an "efficiency enhancement license" that activates the pre-defined operating point curve and allows the customer to save energy and money.

[0047] A method of operating a PA, such as PA 226 described above, is illustrated in the PA dynamic operating point control flow diagram 300 of Figure 3. The PA dynamic operating point control flow diagram 300 is provided as a sequence of blocks. The sequence of the blocks may occur in a different order or in parallel in other examples. Hence, the present application is not limited to the sequential sequence of blocks set out in Figure 3.

[0048] At block 302. the power level of an output signal from PA 226 is measured. Power measurement may be done with a closed feedback loop 260 described above using a power detector 248. The feedback loop may in an example, include an analog to digital converter. At block 304, the temperature of PA 226 is measured. In an example this may be done with a temperature sensor 210 that is placed or positioned to measure the temperature of the PA 226.

[0049] Using the measured power and measured temperature, it is then determined an operating point of PA 226 at block 306. In one example, this is done with the use of a lookup table, such as table 206, that contains data from a dynamic optimized operating curve associated with PA 226 for a given output power and measured temperature. In examples, the dynamic optimized operating point curve is defined that ensures an optimized power consumption of PA 226 is achieved. The optimized operating point curve is saved in the lookup table 206. An example of a dynamic optimized operating point curve is dynamic optimized operating point curve 502 discussed below⁷ in view of Figure 5.

[0050] At block 308, the bias gate voltage of PA 226 is adjusted pursuant to the determined operating point. Since it is dynamic, the process continues back at blocks 302 and 304 periodically measuring power and temperature respectively.

[0051] Referring to Figure 4, a change in gate voltage verses change in power consumption graph 400 is illustrated including a hardware curve 404 and a simulation curve 402. Figure 4 illustrates that the power consumption of an exemplary pow er amplifier is reduced by more than 20 percent at the same output power (exemplary measured at 35dBm, 40dBm and 44.5dBm) if the corresponding bias gate voltage(s) of the PA is/are reduced by about 14 percent. The use of curve point data from the dynamic operating point curve ensures an optimized power consumption when the PA is driven by idle mode signals or signals with reduced resource block allocations (back-off operation or low user traffic). In addition to the ideal operating point at nominal conditions, transient operating curve tracking allows for improved efficiency and linearity over output power. This is due to a bias gate voltage of the PA having an effect on the PA’s gain.

[0052] Further, curve point data that also takes into consideration temperature is used in examples. In this example, a three-dimensional (3D) curve is used. An example of a 3D curve is dynamic optimized operating point curve 502 in a relative bias gate voltage verses temperature verses power graph 500 of Figure 5. Data of the results of the dynamic operating point curve are stored in lookup table 206 in memory 204 and is used by the controller 202 in setting the control voltage of the PA 226. The data of the dynamic optimized operating point curve may be obtained by simulation or experimentation by testing the PA across varying parameters.

[0053] In an embodiment, a tradeoff between AM/ AM behavior and power consumption for idle mode or low traffic signals may be made. A power gain verses output power graph 600 is illustrated in Figure 6. In the power gain verses input power graph 600, the Vgs equals bias gate voltage. In this specific case the flattened power gain curve 602 is a compromise between good EVM and improved back-off current consumption. The dynamic operating point transfer function can be defined and employed by a closed loop power measurement using A/D converter or power sensor/ detector as discussed above.

EXAMPLE EMBODIMENTS

[0054] Example 1 is a power amplifier circuit having a dynamic range. The power amplifier circuit includes a power amplifier with a transistor, a bias control, a power detector, a temperature sensor, a controller and a memory. The bias control is coupled to control a bias gate voltage of the transistor. The power detector is in a feedback loop that is coupled to an output of the transistor. The temperature sensor is positioned to measure a temperature related to the power amplifier. The controller is coupled to control the bias control. The controller is further in communication with the power detector in the feedback loop and the temperature sensor. The controller is configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector. The memory' is in communication with the controller and is used to store at least operating instructions implemented by the controller and the lookup table.

[0055] Example 2 includes the power amplifier circuit of Example 1, further including a directional coupler coupled to the output of the power amplifier. The feedback loop is coupled to an output of the directional coupler.

[0056] Example 3 includes the power amplifier circuit of any of the Examples 1-2. further including a circulator and a switch. The circulator has a first port that is in communication with an output of the power amplifier. The circulator has a second port that is in communication with an output of the power amplifier circuit. The circulator includes a third port. The switch is coupled to the third port of the circulator. A first pole of the switch is coupled to a termination. A second pole of the switch is coupled to a receiver input of a radio transceiver.

[0057] Example 4 includes the power amplifier circuit of any of the Examples 1-3, wherein the controller is further configured to; periodically measure a power level of an output signal of the power amplifier with the power detector, periodically measure a temperature relating to the power amplifier with the temperature sensor, determine an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and the then current measured temperature of the power amplifier, and adjust the bias gate voltage of the transistor of the power amplifier based on the determined operating point.

[0058] Example 5 includes the power amplifier circuit of any of the Examples 1- 4, wherein the power amplifier is a dual-input amplifier.

[0059] Example 6 includes the power amplifier of Example 5, wherein the dual-input amplifier is a dual-input Doherty power amplifier in a digital pre-distortion system.

[0060] Example 7 includes the power amplifier of Example 6, further including a splitter and an output combiner. The splitter has a first input that is in communication a radio transceiver output and a second input that is coupled to a termination. Each input of the transistor of the dual-input Doherty' power amplifier is coupled to an associate output of the spliter. The output combiner configured to combine signals output from the transistor of the dual-input Doherty power amplifier, an output of the output combiner in communication with a power amplifier circuit output.

[0061] Example 8 includes the power amplifier circuit of any of the Examples 1-7, wherein the power amplifier is part of front end that includes a radio transceiver. The radio transceiver includes a transmiter output, a power amplifier circuit output, a receiver input and a digital pre-distortion feedback. The transmiter output is in communication with an input to power amplifier. The power amplifier circuit output is in communication with the output of the power amplifier. The receiver input is in communication with a time division duplex switch and the digital pre-distortion feedback is in communication with the feedback loop.

[0062] Example 9 includes a communication system. The communication system includes at least one base station, at least one remote antenna unit, and at least one master unit. The at least one base station is in communication with at least one wireless network communication operator. The at least one remote antenna unit is configured to wirelessly communicate with mobile devices. At least one remote unit of the at least one remote unit includes a power amplifier circuit having a dynamic range. The power amplifier circuit includes a power amplifier with a transistor, a bias control, a power detector, a temperature sensor, a controller and a memory. The bias control is coupled to control a bias gate voltage of the transistor of the power amplifier. The power detector, that is in a feedback loop, is coupled to an output of the power amplifier. The temperature sensor is positioned to measure a temperature related to the power amplifier. The controller is coupled to control the bias control. The controller is further in communication with the power detector in the feedback loop and the temperature sensor. The controller is configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector. The memory is in communication with the controller to store at least operating instructions implemented by the controller and the lookup table. The at least one master unit is configured to interface communications between the at least one base station and the at least one remote antenna unit. [0063] Example 10 includes the communication system of Example 9, wherein the power amplifier circuit further includes a directional coupler that is coupled to the output of the power amplifier. The feedback loop is further coupled to an output of the directional coupler.

[0064] Example 11 includes the communication system of any of the Examples 9-10, wherein the power amplifier circuit further includes a circulator and a switch. The circulator has a first port that is in communication with the output of the power amplifier. The circulator has a second port that is in communication with a power amplifier circuit output. The circulator further includes a third port. The switch is coupled to the third port of the circulator. A first pole of the switch is coupled to a termination. A second pole of the switch is coupled to a receiver input of a radio transceiver.

[0065] Example 12 includes the communication system of any of the Examples 9-11, wherein the controller is further configured to; periodically measure a power level of an output signal of the power amplifier with the power detector, periodically measure a temperature relating to the power amplifier with the temperature sensor, determine an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and the then current measured temperature of the power amplifier, and adjust the bias gate voltage of the power amplifier based on the determined operating point.

[0066] Example 13 includes the communication system of any of the Examples 9-12, further including a point-of-interface for each base station interfacing communications between an associated base station and the at least one master unit.

[0067] Example 14 includes the communication system of any of the Examples 9-13, further including at least one intermediate unit. The master unit communicating to at least one of the remote antenna units through the at least one intermediate unit.

[0068] Example 15 includes the communication system of any of the Examples 9-14, further including at least one extension unit that is in communication with one of the at least one remote antenna unit. The at least one extension unit is configured to at least one of increase a number of remote antenna units the at least one master unit can communicate with, increase a master-unit-to-remote-antenna-unit distance, and reduce an amount of cabling needed to couple the at least one master unit to an associated remote antenna unit of the at least one remote antenna unit.

[0069] Example 16 includes a method of operating a power amplifier in a communication system. The method includes periodically measuring a power level of an output signal of the power amplifier with a power detector; periodically measuring a temperature relating to the power amplifier with a temperature sensor; determining an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and a then current measured temperature of the power amplifier; and adjusting a bias gate voltage of a transistor of the power amplifier based on the determined operating point.

[0070] Example 17 includes the method of Example 16, wherein determining the operating point of the power amplifier further includes locating the operating point in a lookup table that contains data from a dynamic optimized operating point curve.

[0071] Example 18 includes the method of Examples 17, wherein the data from the dynamic optimized operating point curve is obtained is generated by one of simulation and testing of a related power amplifier across varying parameters.

[0072] Example 19 includes the method of any of the Examples 16-18, wherein adjusting the bias gate voltage of the transistor of the power amplifier further includes generating a select bias gate voltage for the transistor of the power amplifier.

[0073] Example 20 includes the method of any of the Examples 16-19, wherein periodically measuring the power level of an output signal of the power amplifier with the power detector further includes using a feedback loop that includes the power detector that is coupled to an output of the power amplifier.

[0074] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

1. A power amplifier circuit having a dynamic range, the power amplifier circuit comprising: a power amplifier including a transistor; a bias control coupled to control a bias gate voltage of the transistor; a power detector in a feedback loop coupled to an output of the power amplifier; a temperature sensor positioned to measure a temperature related to the power amplifier; a controller coupled to control the bias control, the controller further in communication with the power detector in the feedback loop and the temperature sensor, the controller configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector; and a memory in communication with the controller to store at least operating instructions implemented by the controller and the lookup table.

2. The power amplifier circuit of claim 1, further comprising: a directional coupler coupled to an output of the power amplifier, the feedback loop coupled to an output of the directional coupler.

3. The power amplifier circuit of claim 1, further comprising: a circulator having a first port in communication with an output of the power amplifier, the circulator having a second port in communication with an output of the power amplifier circuit, the circulator including a third port; and a switch coupled to the third port of the circulator, a first pole of the switch coupled to a termination, a second pole of the switch coupled to a receiver input of a radio transceiver.

4. The power amplifier circuit of claim 1 , wherein the controller is further configured to: periodically measure a power level of an output signal of the power amplifier with the power detector; periodically measure a temperature relating to the power amplifier with the temperature sensor; determine an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and the then current measured temperature of the power amplifier; and adjust the bias gate voltage of the transistor of the power amplifier based on the determined operating point.

5. The power amplifier circuit of claim 1 , wherein the power amplifier is a dual-input amplifier.

6. The power amplifier circuit of claim 5, where the dual-input amplifier is a dual-input Doherty power amplifier in a digital pre-distortion system.

7. The power amplifier circuit of claim 6, further comprising: a splitter having a first input in communication with a radio transceiver output and a second input coupled to a termination, each input of the transistor of the dual-input Doherty power amplifier coupled to an associate output of the splitter; and an output combiner configured to combine signals output from the transistor of the dual-input Doherty power amplifier, an output of the output combiner in communication with a power amplifier circuit output.

8. The power amplifier circuit of claim 1, wherein the power amplifier is part of front end that includes a radio transceiver, the radio transceiver comprising: a transmitter output in communication with an input to power amplifier; a power amplifier circuit output in communication with the output of the power amplifier; a receiver input in communication with a time division duplex switch; and a digital pre-distortion feedback in communication with the feedback loop.

9. A communication system comprising: at least one base station in communication with at least one wireless network communication operator; at least one remote antenna unit configured to wirelessly communicate with mobile devices, at least one remote unit of the at least one remote unit including a power amplifier circuit having a dynamic range, the power amplifier circuit including, a power amplifier including a transistor, a bias control coupled to control a bias gate voltage of the transistor of the power amplifier, a power detector in a feedback loop coupled to an output of the power amplifier, a temperature sensor positioned to measure a temperature related to the power amplifier, a controller coupled to control the bias control, the controller further in communication with the power detector in the feedback loop and the temperature sensor, the controller configured to control the bias control based on an operating point in a lookup table determined by a then current temperature measurement from the temperature sensor and a then current power signal from the power detector, and a memory in communication with the controller to store at least operating instructions implemented by the controller and the lookup table; and at least one master unit configured to interface communications between the at least one base station and the at least one remote antenna unit.

10. The communication system of claim 9, wherein the power amplifier circuit further comprises: a directional coupler coupled to the output of the power amplifier, the feedback loop coupled to an output of the directional coupler.

11. The communication system of claim 9, wherein the power amplifier circuit further comprises: a circulator having a first port in communication with the output of the power amplifier, the circulator having a second port in communication with a power amplifier circuit output, the circulator including a third port; and a switch coupled to the third port of the circulator, a first pole of the switch coupled to a termination, a second pole of the switch coupled to a receiver input of a radio transceiver.

12. The communication system of claim 9, wherein the controller is further configured to: periodically measure a power level of an output signal of the power amplifier with the power detector; periodically measure a temperature relating to the power amplifier with the temperature sensor; determine an operating point of the pow er amplifier based on a then current measured power level of the output signal of the power amplifier and the then current measured temperature of the power amplifier; and adjust the bias gate voltage of the power amplifier based on the determined operating point.

13. The communication system of claim 9, further comprising: a point-of-interface for each base station interfacing communications between an associated base station and the at least one master unit.

14. The communication system of claim 9, further comprising: at least one intermediate unit, the master unit communicating to at least one of the remote antenna units through the at least one intermediate unit.

15. The communication system of claim 9, further comprising: at least one extension unit in communication with one of the at least one remote antenna unit, the at least one extension unit configured to at least one of increase a number of remote antenna units the at least one master unit can communicate with, increase a master- unit-to-remote-antenna-unit distance, and reduce an amount of cabling needed to couple the at least one master unit to an associated remote antenna unit of the at least one remote antenna unit.

16. A method of operating a power amplifier in a communication system, the method comprising: periodically measuring a power level of an output signal of the power amplifier with a power detector; periodically measuring a temperature relating to the power amplifier with a temperature sensor; determining an operating point of the power amplifier based on a then current measured power level of the output signal of the power amplifier and a then current measured temperature of the power amplifier; and adjusting a bias gate voltage of a transistor of the power amplifier based on the determined operating point.

17. The method of claim 16. wherein determining the operating point of the power amplifier further comprises: locating the operating point in a lookup table that contains data from a dynamic optimized operating point curve.

18. The method of claim 17, wherein the data from the dynamic optimized operating point curve is obtained is generated by one of simulation and testing of a related power amplifier across vary ing parameters.

19. The method of claim 16. wherein adjusting the bias gate voltage of the transistor of the power amplifier further comprises: directing a bias voltage controller to generate a select bias gate voltage for the transistor of the power amplifier.

20. The method of claim 16, wherein periodically measuring the power level of an output signal of the power amplifier with the power detector further comprising: using a feedback loop that includes the power detector that is coupled to an output of the power amplifier.