Various apparatuses and methods are described where a signal is amplified using a chopper amplifier arrangement, and ripples caused by said chopper amplifier arrangement are reduced. In some cases, this reduction of ripples is performed by controlling a voltage offset of an amplifier of said chopper amplifier arrangement. In other embodiments, a detection of ripples or a chopping of the chopper amplifier arrangement is at least temporarily disabled.

In a class-D amplifier, oscillation phenomenon is suppressed in a high RF range and surge voltage is reduced. An oscillation absorption circuit is connected on the power supply side of the class-D amplifier circuit, and the class-D amplifier circuit and thus connected oscillation absorption circuit equivalently configure an oscillation circuit. Resistance provided in the oscillation absorption circuit is assumed as damping resistance of the oscillation circuit, thereby suppressing the oscillation phenomenon and reducing the surge voltage. The oscillation absorption circuit is made up of the RL parallel circuit of resistance and inductance. The oscillation absorption circuit and the class-D amplifier circuit constitute the oscillation circuit, and the resistance of the oscillation absorption circuit constitutes the damping resistance of the oscillation circuit in the high RF range.

An audio amplifier, including: at least a two stage amplifier configured to receive an input signal and output an amplified output signal, the at least a two stage amplifier including at least one stage amplifier and an output stage amplifier; and an auxiliary stage amplifier having an input coupled to an output of the at least one stage amplifier and an input of the output stage amplifier.

A circuit may include a two-stage feedforward compensated operational transconductance integrated amplifier, and the two-stage feedforward compensated operational transconductance integrated amplifier may include an input terminal, an output terminal, a signal path between the input terminal and the output terminal, the signal path comprising a first signal path gain stage and a second signal path gain stage, and ripple rejection circuitry coupled between the input terminal and an intermediate node of the signal path located between the first signal path gain stage and the second signal path gain stage. The ripple rejection circuitry may include a first ripple rejection circuitry gain stage coupled at its input to the input terminal and coupled at its output to an input terminal of a chopper circuit, a notch filter coupled at its input to an output terminal of the chopper circuit, and a second ripple rejection circuitry gain stage coupled at its input to an output terminal of the notch filter and coupled at its output to the intermediate node.

A chopper amplifier circuit includes a modulator circuit tuned to a chopper frequency, the modulator circuit being configured, in accordance with the chopper frequency, to convert a voltage into an AC voltage; an amplifier circuit having an inverting input and a non-inverting input for the AC voltage, and having an inverting output and a non-inverting output for providing an amplified AC voltage; and a demodulator circuit tuned to the chopper frequency, the demodulator circuit being configured to convert the amplified AC voltage into an amplified DC voltage. The demodulator circuit is configured to, during different switching phases, couple each of the inverting and non-inverting outputs of the amplifier circuit, both directly and capacitively, to each inverting and non-inverting input of a summing circuit.

An instrumentation amplifier can include: an input port configured to receive a sensor signal; a first-stage amplifier configured to amplify the sensor signal to obtain a first intermediate signal; a first high-pass filter circuit, having input terminals coupled to output terminals of the first-stage amplifier, and being configured to eliminate a signal that is in the first intermediate signal and associated with an offset voltage of the first-stage amplifier, in order to obtain a second intermediate signal; a first chopper, having input terminals coupled to output terminals of the first high-pass filter circuit, and being configured to perform chopper modulation and demodulation on the second intermediate signal to obtain a third intermediate signal; and a second-stage amplifier, having input terminals coupled to output terminals of the first chopper, and being configured to amplify the third intermediate signal to generate an output signal.

The present disclosure relates to chopper amplifier circuits featuring inherent chopper ripple suppression. A chopper amplifier circuit includes a modulator circuit tuned to a chopper frequency, and configured, in accordance with the chopper frequency, to convert a voltage into an AC voltage; an amplifier circuit having inverting and non-inverting inputs for the AC voltage, and having inverting and non-inverting outputs for an amplified AC voltage; a demodulator circuit tuned to the chopper frequency, and configured to convert the amplified AC voltage into an amplified DC voltage, the inverting output being coupled, via a first capacitance in a first signal path, to a first input of the demodulator circuit, the non-inverting output being coupled, via a second capacitance in a second signal path, to a second input of the demodulator circuit; and a discharge resistor circuit coupled on an output side of both capacitances between the first and second signal paths.

A push-pull power amplifier (PA) includes a pair of P-type transistors, a pair of N-type transistors, and a splitter, wherein source terminals of the pair of P-type transistors are coupled to a first reference voltage, source terminals of the pair of N-type transistors are coupled to a second reference voltage, and drain terminals of the pair of P-type transistors and drain terminals of the pair of N-type transistors are coupled to an output port of the push-pull PA. The splitter is arranged to receive a common-mode input pair, and provide two differential output pairs to the pair of P-type transistors and the pair of N-type transistors, wherein one of the two differential output pairs is provided to gate terminals of the pair of P-type transistors, and the other of the two differential output pairs is provided to gate terminals of the pair of N-type transistors.

Switching amplifier circuitry for driving an inductive load, the switching amplifier circuitry comprising modulator circuitry and output stage circuitry, wherein the switching amplifier circuitry is configured to: while the modulator circuitry is outputting a modulated output signal that gives rise to ripple current in the load: adjust a switching frequency of the modulator circuitry over a predetermined range of frequencies; monitor a power of the switching amplifier circuitry as the switching frequency is adjusted over the predetermined range of frequencies; and select, as an operational switching frequency for the modulator circuitry, a frequency within the predetermined range of frequencies at which the monitored power meets a predefined criterion.

A push-pull power amplifier (PA) includes a pair of P-type transistors, a pair of N-type transistors, and a splitter, wherein source terminals of the pair of P-type transistors are coupled to a first reference voltage, source terminals of the pair of N-type transistors are coupled to a second reference voltage, and drain terminals of the pair of P-type transistors and the pair of N-type transistors are coupled to an output port. The splitter receives a common-mode input pair, and provides two differential output pairs, wherein one of the two differential output pairs is provided to gate terminals of the pair of P-type transistors, and the other of the two differential output pairs is provided to gate terminals of the pair of N-type transistors. A voltage ripple at each of the gate terminals of the pair of P-type transistors is equal to a voltage ripple of the first reference voltage.