An amplifier circuit can have a differential input. A common-mode signal present at the differential input can induce an offset voltage at an output of the amplifier circuit. A compensation can be performed to reduce or eliminate such an offset, such as at a first temperature. Circuits and techniques for drift correction can be performed, such as to correct for residual offset error across an entirety of a specified operation temperature range. In an example, first and second drift correction signal generator circuits can be used, such as to provide signals proportional to a common mode voltage, but having different temperature coefficients.

A new compensation system for an audio input reduces noise by matching feedback ratios in the positive and negative paths. A variable resistance network allows for fine control of resistance trimming in one of the signal paths, which allows for compensation between tolerance of resistors that are external to an integrated circuit and those that are internal to the integrated circuit.

Described is an apparatus which comprises: an amplifier to receive a reference voltage; and calibration logic which is operable to receive a first voltage and to provide the reference voltage to the amplifier, wherein the calibration logic is operable to generate a look-up table (LUT) that maps the first voltage to a drive current.

An amplifier circuit can have a differential input. A common-mode signal present at the differential input can induce an offset voltage at an output of the amplifier circuit. A compensation can be performed to reduce or eliminate such an offset, such as at a first temperature. Circuits and techniques for drift correction can be performed, such as to correct for residual offset error across an entirety of a specified operation temperature range. In an example, first and second drift correction signal generator circuits can be used, such as to provide signals proportional to a common mode voltage, but having different temperature coefficients.

A mixed-signal integrated circuit that includes: a global reference signal source; a first summation node and a second summation node; a plurality of distinct pairs of current generating circuits arranged along the first summation node and the second summation node; a first current generating circuit of each of the plurality of distinct pairs that is arranged on the first summation node and a second current generating circuit of each of the plurality of distinct pairs is arranged on the second summation node; a common-mode current circuit that is arranged in electrical communication with each of the first and second summation nodes; where a local DAC adjusts a differential current between the first second summation nodes based on reference signals from the global reference source; and a comparator or a finite state machine that generates a binary output value current values obtained from the first and second summation nodes.

In at least one example, a circuit includes an amplifier, a first feedback loop, and a second feedback loop. The amplifier includes an amplifier input and an amplifier output. The first feedback loop includes a first feedback capacitor and a first switch. The first feedback loop is coupled between the amplifier input and the amplifier output. The first feedback capacitor is coupled to the amplifier output through the first switch. The second feedback loop includes a second feedback capacitor and a second switch. The second feedback loop is coupled in parallel with the first feedback loop between the amplifier input and the amplifier output. The second feedback capacitor is coupled to the amplifier input and to the first feedback capacitor through the second switch.

In at least one embodiment, a fully differential amplifier is provided. A first amplifying circuit receives a first input voltage signal and provides a first output voltage signal. A second amplifying circuit to receive a second voltage signal and to provide a second output voltage signal. A summing circuit to provide a common mode component of the first input voltage signal and the second input voltage signal. A compensation circuit to amplify the common mode component of the first input voltage signal and the second input voltage signal and output an injection signal. A common gain setting network including a plurality of resistors to receive the injection signal and to interface with the first amplifying circuit, the second amplifying circuit, and the compensation circuit to prevent the common mode component from being present in the first output voltage signal and the second output voltage signal.

The present disclosure provides an inductive magnetic sensor, which includes a signal pre-amplifying measurement circuit, a feedback loop, a magnetic core and coil group, a low-noise autozero processing circuit, and an output protection module. The magnetic core and coil group is electrically connected between the signal pre-amplifying measurement circuit and the feedback loop, the signal pre-amplifying measurement circuit comprises the low-noise autozero processing circuit, and the feedback loop and the low-noise autozero processing circuit are electrically connected to the output protection module respectively. By introducing the resonant notch filter, it may extend the passband to the low frequency, and extend the low-frequency characteristic of the magnetic sensor, to obtain a better low-frequency magnetic sensor. The present disclosure further provides an electromagnetic prospecting equipment.

The operational amplifier disclosed includes an input stage configured to receive power from a floating supply circuit in in a low voltage range that can float according to the common mode voltage at the input. The low voltage supply facilitates the use of low voltage components that can improve the precision of the operational amplifier by lowering the offset voltage. The input stage utilizes a first gain block and a second gain block. The first gain block is configured to have a low offset voltage while the second gain h block is configured to have a high gain. Dividing these aspects over separate gain blocks improves the precision and noise performance of the operational amplifier. The operational amplifier has high gain at low frequencies and at high frequencies due to a topology that combines a low gain, high bandwidth path with a high gain, low bandwidth path at the output.

Provided is a differential amplification device reduced in DC offset voltage. The amplification device amplifies an input signal, and includes a chopper switch circuit which switches the polarity of the input signal between a normal phase and a reverse phase and outputs the input signal, a V-I conversion circuit which is connected to the chopper switch circuit, a capacitance circuit which is connected to the V-I conversion circuit to store electric charges supplied from the V-I conversion circuit, and an amplification circuit which is connected to the V-I conversion circuit to switch the polarity of an input signal between the normal phase and the reverse phase and amplify the input signal.