An amplifier circuit including an input amplifier, an output amplifier and a diode device is provided. The output amplifier is coupled to the input amplifier and outputs an output voltage. The diode device is coupled between an output end and an input end of the output amplifier. When a voltage difference between the output end and the input end of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on, and an overshoot of the output voltage is reduced.

An apparatus includes an amplifier, an input port, a first modulator circuit connected to the input port, and a correction circuit. The correction circuit is configured to determine a common mode voltage of the input port and receive a first clock signal. The correction circuit is further configured to manipulate, based at least in part upon the common mode voltage of the input port, the first clock signal to generate a second clock signal. The second clock signal is produced for the first modulator circuit. The correction circuit is further configured to determine whether the second clock signal is out of phase with a third clock signal, and, based upon a determination that the second clock signal is out of phase with the third clock signal, reset the second clock signal.

A differential input amplification-stage circuit comprises a voltage unit, first and second bulk-driven transistors, first and second mirror current sources, and a differential amplifier unit. The first and the second bulk-driven transistors respectively receive first and second input voltages, and converts the first and the second input voltages into first and second output currents. The differential amplifier unit separately outputs first and second adjustment currents under an action of voltages output by the first to the third voltage output ends. The first and the second mirror current sources respectively output first and second predetermined currents according to the first output current and the first adjustment current, and the second output current and the second adjustment current, so as to maintain transconductance constancy of the differential input amplification-stage circuit. Therefore, output stability is improved.

Apparatus and methods are described for providing a mixed-signal full-wave precision rectifier. In one example of the disclosed technology, a full-wave rectifier circuit includes a comparator configured to output a logic 1 or logic 0 by comparing an analog input signal to a reference voltage. The circuit further includes an analog switch with a control input coupled to the comparator output. A first input of the analog switch is coupled to the analog electrical input and a second input of the analog switch is coupled to a reference input voltage. The switch thus selects the input signal or the reference signal to output based on the output of the comparator. An amplifier is coupled to receive the analog switch output and generate a signal following the input in an inverting or a non-inverting mode depending on the selected analog switch output, thereby generating a rectified full-wave output of the analog input signal.

Aspects are directed to an amplifier circuit including a signal processing circuit and a calibration circuit. In certain specific embodiments, the signal processing circuit includes a signal combiner and a closed-loop feedback path, and the signal processing circuit is designed to provide a loop transfer function for a derived signal partly representing contributions from an audio input signal, a control or pilot signal having a target frequency range, and a calibration signal. The signal combiner is designed to combine aspects of the control or pilot signal and aspects of the audio input signal, and the calibration circuit is designed to adjust an effective gain of the derived signal in response to whether a unity-gain frequency of a signal in the closed-loop feedback path, as provided via the loop transfer function, is higher or lower than the target frequency range. Consistent therewith and in yet more specific embodiments, such an amplifier circuit can define the target frequency range relative to the transfer function and an associated unity-gain frequency.

An amplifier circuit may include a first gain stage configured to receive an input signal at the first gain stage input and apply a first gain to the input signal to generate a first gain stage output signal at the first gain stage output, a second gain stage configured to receive the first gain stage output signal at the second gain stage input and apply a second gain to the first gain stage output signal to generate a second gain stage output signal at the second gain stage output, a feedforward gain stage configured to receive the input signal at the feedforward gain stage input and apply a feedforward gain to the input signal to generate a feedforward gain stage output signal at the feedforward gain stage output, and a compensation network coupled between the first gain stage output and the feedforward gain stage output.

Bias circuits for CMOS power amplifiers are provided. The bias circuit includes a feedback module, a first bias module, and a second bias module. The feedback module has a first input connected to a output common mode voltage, a second input connected to a reference voltage, and an output connected to gates of main amplification transistors in a first differential amplification module; based on a difference between the output common mode voltage and the reference voltage, the feedback module adjusts gate voltages of main amplification transistors until the output common mode voltage is equal to the reference voltage; the first bias module provides bias voltages for the first differential amplification module; the second bias module provides bias voltages for a second differential amplification module. The present disclosure adopts direct negative feedback and cascoded current mirrors, which realize accurate DC gate bias and accurate control of the output common mode voltage.

An amplifier circuit including an input amplifier, an output amplifier and a diode device is provided. The output amplifier is coupled to the input amplifier and outputting an output voltage. The diode device is coupled between an output end and an input end of the output amplifier. When a voltage difference between the output end and the input end of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on, and an overshoot of the output voltage is reduced. The diode device includes a variable resistor to increase the barrier voltage of the diode device.

An amplifier includes an output stage circuit and a compensation circuit. The output stage circuit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The compensation circuit includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. The first capacitor is coupled between the first input terminal and the second output terminal, and is configured to operate as a first Miller capacitor. The second capacitor is coupled between the second input terminal and the first output terminal, and is configured to operate as a second Miller capacitor. The third capacitor and the fourth capacitor are configured to alternately operate as the first Miller capacitor and the second Miller capacitor according to at least one clock signal.

The disclosed technology relates to a method for improving performance of a feedback circuit comprising an amplifier and a feedback network, wherein the feedback circuit has at least one tunable component. In one aspect, the method comprises measuring first amplitude values at an input of the amplifier and second amplitude values at an output of the amplifier, estimating a linear open-loop gain of the amplifier based on both the amplitude values, estimating a linear finite gain error based on the estimated gain and the second amplitude values, subtracting the linear finite gain error from the first amplitude values to derive a set of samples containing second error information, deriving an signal-to-noise-plus-distortion ratio estimate based on the variance of the set of samples and a variance of the second amplitude values, and adjusting the feedback circuit in accordance with the signal-to-noise-plus-distortion ratio estimate.