Aspects disclosed herein eliminate audible disturbances that may occur when an audio amplifier is activated and deactivated. A feedback circuit is used to maintain a closed loop when transistors of a power output stage are activate or deactivated, thereby enabling the charge to build or dissipate without causing an audible disturbance. Further, in certain implementations, the power output stage may remain in an enable state for a period of time after deactivation of the audio amplifier regardless of whether an audio input signal is received enabling dissipation of charge without causing an audible disturbance.

In described examples, an amplifier can be arranged to generate a first stage output signal in response to an input signal. The input signal can be coupled to control a first current coupled from a first current source through a common node to generate the first stage output signal. A replica circuit can be arranged to generate a replica load signal in response to the input signal and in response to current received from the common node. A current switch can be arranged to selectively couple a second current from a second current source to the common node in response to the replica load signal.

Implementations provide a receiver circuit that includes: an alternate current (AC)-coupling network to filter an input signal, the AC-coupling network including a first RC filter connected between a first input node and a first common node and a second RC filter connected between a second input node and the first common node; a differential amplifier coupled to the AC-coupling network and configured to receive a filtered input signal from the AC-coupling network and generate an output signal, the differential amplifier including a differential pair of transistors and a common-mode measurement network coupled to source terminals of a first and a second transistors in the differential pair; and a first operational amplifier having an input coupled to output terminal of the common-mode measurement network and an output coupled to the first common node.

Certain aspects are directed to an amplifier. The amplifier generally includes a first transistor having a gate coupled to an input node of the amplifier, a source degeneration circuit, and a second transistor coupled between the source degeneration circuit and a source of the first transistor, a gate of the second transistor being configured to receive a gain control signal from a controller.

An example apparatus includes: a first voltage source, a first amplifier having a noninverting input adapted to be coupled to a photodiode anode and coupled to the first voltage source, an inverting input adapted to be coupled to a photodiode cathode, and an output, a first resistor coupled to the first amplifier inverting input and to the first amplifier output, a first capacitor coupled to the inverting input of the first amplifier and the first amplifier output, and a second voltage source different from the first voltage source. There is a second amplifier having a noninverting input, an inverting input and an output. The noninverting input is coupled to the output of the first amplifier, the inverting input is coupled to the second voltage source, and there is a second resistor coupled to the inverting input and the output of the second amplifier.

Systems and methods are provided for improved noise performance of audio amplifiers. In one example, a system includes a multistage amplifier comprising at least a first stage amplifier and a second stage amplifier. The system further includes a plurality of switches disposed within the multistage amplifier to configure the multistage amplifier. The system further includes a control signal configured to control the multistage amplifier to a normal amplification mode or a mute state, wherein the multistage amplifier is adapted to amplify an input signal in the normal amplification mode, the multistage amplifier is adapted to output a zero signal in the mute state, and internal amplification stages of the multistage amplifier are disabled in the mute state, and output stages of each of the at least first stage amplifier and the second stage amplifier are electrically shorted and/or shorted to a fixed bias voltage in the mute state.

Implementations provide a receiver circuit that includes: an alternate current (AC)-coupling network to filter an input signal, the AC-coupling network including a first RC filter connected between a first input node and a first common node and a second RC filter connected between a second input node and the first common node; a differential amplifier coupled to the AC-coupling network and configured to receive a filtered input signal from the AC-coupling network and generate an output signal, the differential amplifier including a differential pair of transistors and a common-mode measurement network coupled to source terminals of a first and a second transistors in the differential pair; and a first operational amplifier having an input coupled to output terminal of the common-mode measurement network and an output coupled to the first common node.

A display compensation circuit includes a driver circuit including a digital-to-analog converter (DAC), the driver circuit configured to drive pixels of a display panel; and a compensation circuit including a current-mode sensing circuit and a reference current generator circuit, the compensation circuit configured to determine a value to compensate for pixel variations across the display panel, the reference current generator circuit configured to generate a reference current using the DAC of the driver circuit.

A low-voltage high-speed programmable equalization circuit includes a gain boosting amplifier stage, a CML differential amplifier stage, and an emitter follower. An input terminal of the gain boosting amplifier stage serves as an input terminal of the equalization circuit. An output terminal of the gain boosting amplifier stage is connected to an input terminal of the CML differential amplifier stage. An output terminal of the CIVIL differential amplifier stage is connected to an input terminal of the emitter follower. An output terminal of the emitter follower serves as an output terminal of the equalization circuit.

A differential power amplifier (DPA) includes an p-side and a n-side half circuit. The p-side and n-side half circuits include an p-side and n-side base, which receive respective in-phase and out-of-phase signals of a differential signal. The DPA includes an p-side biasing circuit and a n-side biasing circuit. The p-side and n-side biasing circuit are configured to provide a controllable p-side and n-side biasing signal to the p-side and n-side base, respectively. The DPA includes a power source which provides positive DC voltage to the controller of the p-side and n-side half circuits. The DPA includes supply and grounding circuit structure which provides common mode DC paths and balances the n-side and p-side half circuits to provide a radio frequency (RF) virtual ground to an emitter of the n-side half circuit and p-side half circuit.