According to certain embodiments, a method of operating an electronic device includes identifying an RSSI value and setting a power amplifier to a first power amplification mode or a second power amplification mode based on the identified one or more RSSI value, wherein the first power amplification mode and the second power amplification mode supply different supply voltages to the power amplifier.

[Problem] To provide a monitoring system capable of monitoring, without stopping operations for a long period of time, a change of the characteristics of an apparatus to be subjected to characteristic measurement, to which high frequency signals are inputted. [Solution] A signal to be monitored and a reference signal are inputted to an input unit 11, and the input unit inputs one of the inputted signals to an apparatus 15 to be subjected to characteristic measurement. On the basis of an output signal of the apparatus 15 and the reference signal in the cases where the reference signal is inputted to the apparatus, an input/output characteristic calculation unit 12 calculates the input/output characteristics of the apparatus 15. On the basis of calculation results obtained from the input/output characteristic calculation unit 12, a correction result generating unit 13 generates a correction result signal that indicates the results obtained by correcting an output signal of the apparatus 15 in the cases where the signal to be monitored is inputted to the apparatus. On the basis of the correction result signal generated by the correction result generating unit 13, a failure determining unit 14 determines whether the apparatus has a failure.

An amplifier circuit is provided. The amplifier circuit includes an amplifier stage; a plurality of variable transistors connected to the amplifier stage; a transconductor connected to at least one of the plurality of variable transistors; and a hybrid differential envelope detector and full-wave rectifier connected to the transconductor.

An audio amplifier system is described comprising: a variable gain audio processor for processing digital audio signal, a digital to analog converter coupled to the audio processor, and configured to receive the processed digital audio signal, a variable gain amplifier having an input coupled to the output of the digital to analog converter and operably connected to a power supply, a controller coupled to the variable gain audio processor and the variable gain amplifier and configured to switch the audio amplifier system between a first operating mode having a first power supply voltage value and a second operating mode having a second higher power supply voltage value; wherein the controller is operable in the first operating mode to set the audio amplifier system gain to a desired gain value and in the second operating mode to maintain the desired gain value.

A Doherty amplifier is able to enhance efficiency in low-power and high-power RF communication states by enabling carrier and peaking amplifiers as required, and controlling bias modulation, depending on traffic loading levels in each of a set of consecutive communications timeslots. For example, if, in a low-power state, traffic loading levels do not exceed a relatively lower threshold in a communications timeslot, carrier amplifiers are selectively enabled as needed, peaking amplifiers are not enabled, and carrier amplifier bias levels are kept substantially constant. If, in an intermediate-power state, the lower threshold is exceeded but a relatively higher threshold is not exceeded, all carrier amplifiers are enabled, peaking amplifiers are selectively enabled, and bias levels are kept substantially constant. If, in a high-power state, the higher threshold is exceeded, all carrier and peaking amplifiers can be enabled, and the peaking amplifier bias tracks the RF envelope of the received RF signal.

Power amplifier circuitry includes an amplifier stage, a non-linear compensation network, and non-linear compensation control circuitry. The amplifier stage includes an input and an output, and is configured to receive an input signal at the input and provide an amplified output signal at the output. The non-linear compensation network is coupled between the input and the output of the amplifier stage. The non-linear compensation control circuitry is coupled to the non-linear compensation network and one or more of the input and the output of the amplifier stage. The non-linear compensation control circuitry is configured to adjust a capacitance of the non-linear compensation network to cancel a parasitic capacitance associated with the amplifier stage and thus reduce AM-PM distortion.

Systems and methods for improving power amplifier operation are provided. A system may include a baseband signal generator communicatively coupled to a baseband signal digital-to-analog converter. The baseband signal digital-to-analog converter may be communicatively coupled to two or more power amplifiers. The system may also include an envelope signal generator communicatively coupled to an envelope signal digital-to-analog converter. The system may further include a supply modulator communicatively coupled to the envelope signal digital-to-analog converter and the two or more power amplifiers for shared envelope tracking across the two or more power amplifiers.

A wireless radio frequency transceiver system for Internet of Things includes: a wireless radio frequency transmission module and a wireless radio frequency receiving module. The wireless radio frequency transmission module is used to shape signal waveform of digital signals from the Internet of Things to modulate the digital signals to form modulated output signals, and adopt a self-mixing technique to increase voltage/current amplitude of the modulated output signals and reduce phase noise. The wireless radio frequency transmission module is further used to adopt a current reuse technique to amplify the voltage/current amplitude of the modulated output signals, and transmit the amplified modulated output signals through a first antenna to a wireless channel. The wireless radio frequency receiving module is used to detect carrier input signals received from a second antenna to obtain baseband signals and demodulate the baseband signals to form differential signals. The wireless radio frequency receiving module is further used to amplify voltage/current amplitude of the demodulated differential signals several times in an open loop state to produce digital output signals, and transmit the digital output signals to a back-end signal processor.

An amplifier may include control circuitry that may track a first input signal parameter and, in response, adjust a value of a second input parameter. Input parameter tracking and adjustment may facilitate control of output parameters for the amplifier. For example, an envelope-tracking amplifier may track input signal amplitude and adjust other input parameters in response. The adjustments may facilitate control of output parameters, such as gain or efficiency. The amplifier may further include calibration circuitry to determine adjustment responses to various tracked input parameters.

A linearization circuit that reduces intermodulation distortion in an amplifier output receives a first signal that includes a first frequency and a second frequency and generates a difference signal having a frequency approximately equal to the difference of the first frequency and the second frequency. The linearization circuit generates an envelope signal based at least in part on a power level of the first signal and adjusts a magnitude of the difference signal based on the envelope signal. When the amplifier receives the first signal at an input terminal and the adjusted signal at a second terminal, intermodulation between the adjusted signal and the first signal cancels at least a portion of the intermodulation products that result from the intermodulation of the first frequency and the second frequency.