A chopper amplifier and method of operation are described. The chopper amplifier comprises a first chopper arranged to modulate an input signal using a first chopper signal having a chopper frequency. An amplification stage has an input arranged to receive the chopped signal and an output, and supplies an amplified signal at the output. An output chopper is arranged to integrate the amplified signal using a second chopper signal having the chopper frequency to generate an amplified output signal. The amplification stage is further configured to filter the chopped signal to attenuate signal components having frequencies lower than the chopper frequency.

The disclosure relates to an alternating current (AC) coupling circuit including first and second capacitors having first and second input terminals configured to receive an input differential signal and generate an output differential signal at first and second output terminals of the first and second capacitors. The AC coupling circuit further includes a baseline wander correction circuit configured to make the output differential signal resistant to baseline wander due to the input differential signal including one or more time intervals of unbalanced data. The baseline wander correction circuit includes a differential difference amplifier (DDA) having a first differential input configured to receive the input differential signal, a differential output configured to generate a compensation differential signal, and a second differential input configured to receive the compensation differential signal. The compensation differential signal is applied to the output terminals of the first and second capacitors via a pair of resistors, respectively.

Certain aspects of the present disclosure provide methods and apparatus for implementing an amplification system. The amplification system includes an amplifier comprising differential inputs and an output. The differential inputs include an inverting input and a non-inverting input. The amplification system further includes a feedback path from the output coupled to the inverting input. The feedback path from the output is coupled to at least one of an inverting amplifier or buffer, and the at least one of the inverting amplifier or buffer is further coupled to the non-inverting input.

Disclosed embodiments include a method for reducing amplifier offset drift comprised of receiving a first differential input signal at a first transistor base terminal and a second differential input signal at a second transistor base terminal, coupling the collector of the first transistor to the emitter of a third transistor and the emitter of the second transistor to the emitter of a fourth transistor, then coupling the base of the third transistor to the base of the fourth transistor. The method is also comprised of coupling the collector of the fourth transistor to an output terminal, generating a temperature dependent error correction current to minimize the difference in the amount of current flowing through the third transistor and the amount of current flowing through the fourth transistor, then injecting the error correction current into the emitter terminal of at least one of either the third transistor or the fourth transistor.

Offset compensation circuitry for an amplification circuit. One example embodiment is a method of compensating a primary operational amplifier including: creating, by way of a companion circuit, a square wave having an amplitude, a period, and a direct current bias (DC bias), the amplitude proportional to an offset of the primary operational amplifier; integrating, by the companion circuit, the amplitude of the square wave for less than the period of the square wave, the integrating creates a compensation signal; and applying the compensation signal to the primary operational amplifier.

A system that utilizes an amplified signal is disclosed that includes a plurality of first switches coupled to a plurality of first impedances. A plurality of second switches coupled to a plurality of second impedances. An amplifier having a first input coupled to the plurality of first switches and a second input coupled to the plurality of second switches. A leakage current offset source coupled to the first input of the amplifier, wherein the leakage current offset source cancels a leakage current component of a first current provided from the plurality of first switches to the first input.

A first amplifier circuit includes differential pair transistors that amplify a difference between input voltages and active load transistors connected to the differential pair transistors. A second amplifier circuit amplifies output voltage of the first amplifier circuit. An offset correction current source is connected in parallel with the active load transistors and adjusts electric current flowing through the differential pair transistors to correct offset voltage. An offset correction switch switches a driving state of the offset correction current source. A transconductance proportional current generation circuit generates transconductance proportional current for compensating for temperature drift of offset correction voltage for correcting the offset voltage. The transconductance proportional current is proportional to trans conductance.

Split cascade circuits include multiple cascade paths coupled between voltage supply rails. Each cascade path includes a pair of controllable switches. A feedback path is provided for at least one of the cascade circuit paths. An active load circuit may also have a split cascade structure. Multiple-stage circuits, for implementation in Trans-Impedance Amplifiers (TIAs) or analog Receive Front-End modules (RXFEs), for example, include multiple stages of split cascade circuits.

A detection device includes a driving circuit which drives a vibrator, and a detection circuit which detects a desired signal. The driving circuit includes a current-voltage conversion circuit which receives a feedback signal, and performs a current-voltage conversion, a drive signal output circuit which amplifies an input voltage signal after being subjected to the current-voltage conversion, and outputs a drive signal of a sine wave, and a gain control circuit which controls a gain of amplification of the drive signal in the drive signal output circuit. When a resistance for a current-voltage conversion is set to RI, the gain of the amplification of the drive signal in the drive signal output circuit is set to K, and an equivalent series resistance in a fundamental wave mode of the vibrator is set to R, the gain control circuit performs a gain control such that K×RI=R is satisfied.

A semiconductor device in which variations are controlled is provided. The semiconductor device has a function of converting a digital signal into an analog signal, and includes a digital-analog converter circuit, an amplifier circuit, first to fourth switches, a first output terminal, a second output terminal, and a power source. The amplifier circuit is configured to perform feedback control when the first switch and the fourth switch are on and the second switch and the third switch are off. The amplifier circuit is configured to perform comparison control when the first switch and the fourth switch are off and the second switch and the third switch are on; utilizing this, variations in the digital-analog converter circuit and the amplifier circuit are controlled.