Increasing an analog to digital converter (ADC) dynamic range for a communications device. In the communications device, a reference threshold is established for a peak to average power ratio (PAPR) improvement factor for RF signals received by the communications device. A digital to analog converter (DAC) adjustment factor is established for a DAC to account for inaccuracies of a pre-cancellation DAC and fine tuning of an analog gain of received RF signals. A peak amplitude separation element evaluates an absolute value of a portion of a particular RF signal against the reference threshold. Upon the peak amplitude separation element determining that the portion is smaller than the reference threshold, the element assigns a zero value to a DAC signal current sample; otherwise, the element assigns a quantized value of the sample to the DAC signal current sample, used in adjusting a post-cancellation signal sample.

Methods and apparatus for providing adaptive biasing to power amplifiers. Adaptive bias circuits are configured to provide sharp turn on and/or current clamping to improve the efficiency of a power amplifier over a wide input signal bandwidth. Sharp turn on may be achieved using a subtraction technique to subtract outputs from multiple detectors. Clamping may be achieved using MOSFET device characteristics to pull the device from the triode region into the saturation, subtraction techniques to subtract the outputs from multiple detectors, and/or by using circuit devices, such as diodes.

In some embodiments, an audio amplifier can be controlled by a method that includes generating an enable signal based on a masking sound in an audio signal, and controlling a mode transition of the audio amplifier between a current source mode and a voltage source mode based on the enable signal. The mode transition of the audio amplifier can result in an artifact sound, the generating of the enable signal and the controlling of the mode transition can be achieved such that the artifact sound is substantially masked by the masking sound.

Circuits, devices and methods related to mode-switching of amplifiers. In some embodiments, an audio controller can include a mode state engine configured to receive an enable signal and generate a control signal for controlling a mode transition of an amplifier between a current source mode and a voltage source mode, with the mode transition of the amplifier resulting in an artifact sound. The audio controller can further include an enable component configured to provide the enable signal to the mode state engine based on a masking sound in an audio signal, such that the artifact sound is substantially masked by the masking sound during the mode transition of the amplifier.

An apparatus comprises a digital to analog converter (DAC) circuit configured to receive a time-varying a digital input signal and convert the digital input signal to an analog output signal, an output amplifier circuit operatively coupled to the output of the DAC circuit, a peak detector circuit operatively coupled to the input the DAC and configured to produce a signal envelope of the digital input signal, and logic circuitry. The logic circuitry is operatively coupled to the peak detector circuit and is configured to detect when the signal envelope satisfies a specified threshold value; and to adjust a drive capability of an output amplifier circuit of the DAC circuit according to the signal envelope.

An apparatus includes a first predistorter configured to calculate a first predistortion parameter and configured to distort an input signal using the first predistortion parameter to output a first distortion signal, a second predistorter configured to calculate a second predistortion parameter and configured to distort the first distortion signal using the second predistortion parameter to output a second distortion signal, a power supply configured to receive the first distortion signal to generate a first envelope signal, and configured to limit a bandwidth of the first envelope signal to obtain a second envelope signal to supply a source voltage, and a power amplifier configured to receive the source voltage and to output an output signal obtained by amplifying the second distortion signal.

A Regulated Cascode (RGC)-type burst mode optic pre-amplifier having an extended linear input range. The burst mode optic pre-amplifier comprises an RGC-type Trans Impedance Amplifier (TIA), wherein a current path is added in the circuit of the RGC-type TIA to control a linearity state of the RGC-type TIA, and a main voltage gain is controlled in other circuit blocks after the RGC-type TIA.

Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

According to one aspect, embodiments of the invention provide an amplifier system comprising a first phase shifter configured to generate, based on an input signal, a first signal and a second signal, the second signal being out of phase with the first signal, a first amplifier configured to apply a first gain to the first signal to produce a gain adjusted first signal, a second amplifier configured to apply a second gain to the second signal to produce a gain adjusted second signal, a second phase shifter configured to combine the gain adjusted first and second signals to produce an output signal, and a controller configured to identify a high voltage swing across the first amplifier and, in response to identifying the high voltage swing, adjust the first gain to reduce output power of the first amplifier and adjust the second gain to increase output power of the second amplifier.

A transimpedance amplifier (TIA) circuit disclosed includes an input terminal, a first TIA circuit, a second TIA circuit, a field effect transistor (FET), and a gain control circuit. The first TIA circuit outputs a voltage signal from a first output in accordance with an input current received at a first input electrically connected to the input terminal. The second TIA circuit outputs a reference signal from a second output. The FET varies a resistance between a first current terminal and a second current terminal in accordance with a control signal applied to a control terminal. The first current terminal is electrically connected to the input terminal. The second current terminal is electrically connected to the second output of the second TIA circuit. The gain control circuit detects an amplitude of the voltage signal and generates the control signal according to a detection result of the amplitude.