An amplifier circuit comprising: a first amplifier, comprising a voltage input terminal and a voltage output terminal; a voltage offset providing circuit, comprising a first terminal coupled to a first predetermined voltage source, a second terminal coupled to the voltage output terminal, and a third terminal, wherein a voltage at the third terminal is higher than a voltage at the second terminal by an offset voltage; and a voltage control capacitor, comprising a fourth terminal coupled to the third terminal, and a fifth terminal coupled to the voltage input terminal, wherein a capacitance value of the voltage control capacitor corresponds to a voltage difference between a voltage at the fifth terminal and a voltage at the fourth terminal. A better compensation for the amplifier circuit can be acquired since a voltage control capacitor having a capacitance value corresponding to the output voltage of the amplifier is applied.

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.

An amplifier circuit comprising: a first amplifier, comprising a voltage input terminal and a voltage output terminal; a voltage offset providing circuit, comprising a first terminal coupled to a first predetermined voltage source, a second terminal coupled to the voltage output terminal, and a third terminal, wherein a voltage at the third terminal is higher than a voltage at the second terminal by an offset voltage; and a voltage control capacitor, comprising a fourth terminal coupled to the third terminal, and a fifth terminal coupled to the voltage input terminal, wherein a capacitance value of the voltage control capacitor corresponds to a voltage difference between a voltage at the fifth terminal and a voltage at the fourth terminal. A better compensation for the amplifier circuit can be acquired since a voltage control capacitor having a capacitance value corresponding to the output voltage of the amplifier is applied.

A circuit for stabilizing a Class-D audio amplifier having a loop bandwidth modulator configured to modulate a loop bandwidth of the amplifier as a function of one or more control signals, a tuned output filter terminator coupled to a low-pass filter and configured to provide stabilizing control feedback to loop bandwidth modulator, and a carrier injection system configured to provide a wide range fixed frequency operation. Also, a method of stabilizing a feedback network within a Class-D amplifier by providing a first feedback loop coupling an output of a PWM logic stage of the amplifier to an input circuit of the amplifier, providing a second feedback loop coupling an output of a switching output stage of the amplifier to the input circuit, and providing a third feedback loop coupling an output of a low-pass filter of the amplifier to the input circuit.

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.

A radio-frequency (RF) amplifier having a direct response to an arbitrary signal source to output one or more electrosurgical waveforms within an energy activation request, is disclosed. The RF amplifier includes a phase compensator coupled to an RF arbitrary source, the phase compensator configured to generate a reference signal as a function of an arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; and at least one power component coupled to the at least one error correction amplifier and to a high voltage power source configured to supply high voltage direct current thereto, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform.

This invention relates to a self-excited oscillation suppression device and method for the power amplifying circuit, belonging to the field of electronic technology. Said power amplifying circuit includes a FET and a feedback loop. Said device includes: a first compensation circuit which is connected between a drain and a gate of the FET and a second compensation circuit which is connected in parallel with a feedback resistor of said feedback loop. It can solve self-excited oscillation caused by deep negative feedback in the existing power amplifying circuit. The first compensation circuit can shift the open-loop gain curve forward as a whole, and the second compensation circuit can speed up the closure of the feedback gain curve and the open-loop gain curve so that the two curves will close up before the self-excited oscillation; the self-excited oscillation will be suppressed, and the stability of the power amplifying circuit will be improved.

In accordance with an embodiment, a circuit includes: a first super source follower; a compensation circuit having a compensating node configured to provide a voltage of opposite phase of a voltage of an internal node of the first super source follower; and a first compensation capacitor coupled between an input of the first super source follower and the compensating node of the compensation circuit.

In accordance with an embodiment, a circuit includes an amplifier and a programmable capacitor coupled between an output of the first non-inverting and the input of the first amplifier.

An amplifier circuit has a multi-stage amplifier, a compensation capacitor, and compensation circuits. The multi-stage amplifier has amplifiers cascaded between an input port and an output port of the multi-stage amplifier. The amplifiers include at least a first-stage amplifier, a second-stage amplifier and a third-stage amplifier. The compensation capacitor is coupled between the output port of the multi-stage amplifier and an output port of the first-stage amplifier. The compensation circuits include a first compensation circuit and a second compensation circuit. The first compensation circuit is coupled to the output port of the first-stage amplifier. The second compensation circuit is coupled to an output port of the second-stage amplifier.