A circuit device includes a differential input-to-single-ended output first amplifier, to an inversion input terminal of which, of first and second signals forming differential signals, the first signal is input and to a non-inversion input terminal of which the second signal is input, a differential input-to-single-ended output second amplifier, to a non-inversion input terminal of which the first signal is input and to an inversion input terminal of which the second signal is input, and a failure detection circuit that performs failure detection on the basis of an output signal of the first amplifier and an output signal of the second amplifier.

A calibration amplifier includes: a plurality of transistors and a variable resistor configured to change in response to clock pulses. During a calibration cycle, one of the plurality of transistors switches on in each calibration step based on a plurality of enable signals, and a gain of the calibration amplifier changes until an output voltage of the calibration amplifier exceeds a reference voltage and is set to a calibrated gain. The calibration amplifier outputs the output voltage by amplifying an input voltage using the calibrated gain.

An amplifier circuit that includes a first amplifier that has a first input that receives an input signal, a second input and an output. The amplifier circuit also includes a second amplifier that has a first input that is coupled to the output of said the amplifier and a second input. The circuit further includes a first impedance network Z1, a second impedance network Z2, a third impedance network Z3 and a fourth impedance network Z4. The first impedance network Z1 is coupled to a load and the second input of the second amplifier, the second impedance Z2 is connected the output of the first amplifier and the second input of the first amplifier, the third impedance Z3 is connected to the output of the first amplifier and the load, the fourth impedance Z4 is connected the output of the second amplifier and the second input of said first amplifier.

An electronic amplifier has a feedback circuit with a transconductance amplifier.

A reconfigurable operational amplifier includes: a first signal input terminal; a second signal input terminal; an output terminal; an operational amplifier having a non-inverting input, an inverting input, and an output; a negative feedback circuit path from the output of the operational amplifier to the inverting input of the operational amplifier; a first input circuit path from the first signal input terminal to the non-inverting input of the operational amplifier; a second input circuit path from the second signal input terminal to the inverting input of the operational amplifier; an output circuit path from the output of the operational amplifier to the output terminal; and logic units, wherein one or more of the logic units are provided in at least one of the negative feedback circuit path, the first input circuit path, the second input circuit path, and the output circuit path.

An electronic amplifier has a feedback circuit with a transconductance amplifier.

Neural signal amplifiers include an operational amplifier and a feedback network coupled between an output and an input thereof. The feedback network includes a tunnel field effect transistor (TFET) pseudo resistor that exhibits bi-directional conductivity. A drain region of the TFET may be electrically connected to the gate electrode thereof to provide a bi-directional resistor having good symmetry in terms of resistance as a function of voltage polarity.

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.

An amplification circuit includes an amplifier circuit (provided by an operational amplifier) that amplifies a signal to be demodulated. A feedback loop of the amplification circuit has a resistance value that is controlled to discretely vary according to a level of an output node of the amplifier circuit. A comparison of the output level with respect to one or a plurality of thresholds, which define out-of-saturation operating ranges of the amplifier circuit, drives selection of the resistance value.

One example includes an OP-AMP circuit system. The system includes a signal amplification path comprising a signal amplification path comprising a signal amplifier and an output stage. The signal amplification path can be configured to amplify an input voltage received at an input to provide an output voltage via the output stage. The system also includes an offset-reduction path coupled to the input of the signal amplification path and to an output of the signal amplifier. The offset-reduction path includes a transconductance amplifier and at least one chopper that are configured to mitigate noise in the signal amplification path and a noise-filtering feedback path configured to provide chopper feedback with respect to an offset voltage associated with the offset-reduction path, the noise-filtering feedback path comprising a feedback path input coupled to the input of the transconductance amplifier via a resistor.