An amplifier includes input transconductors that receive an input signal, the input signal having a voltage swing. A supply side current mirror generates a gate voltage as a function of input signal voltage and current sources that provide a bias current of the input transconductors as a function of the gate voltage to maintain a constant bias current across the voltage swing of the input signal. Resistors average source voltages of the transconductance-cancelling transconductors to provide an average source voltage and apply the average source voltage to wells of input devices of the transconductance-cancelling transconductors to reduce back bias effect. The input devices are laid out in a same well and have a common centroid to cancel out process mismatches. A first I-DAC trims an offset of first transconductors, and a second I-DAC trims an offset of second transconductors to attain low offsets across a rail-to-rail input common mode range.

A filter includes multiple filter circuits. The filter circuits are coupled in series between an input terminal and an output terminal, to generate an output signal according to an input signal. One of the filter circuits operates as an active filter circuit or a passive filter circuit according to amplitude of the input signal.

Techniques for mitigating noise in a touch signal are disclosed. To reduce or eliminate noise in a touch signal, the touch activity can be filtered out of a touch signal, thus isolating the noise. In some examples, the noise is then provided to the non-inverting input port of a differential amplifier while the unfiltered touch signal is provided to the inverting input port of the differential amplifier. The noise, which is now common on both inputs, is automatically eliminated or reduced by the differential amplifier.

Certain aspects of the present disclosure are generally directed to circuitry and techniques for voltage-to-current conversion. For example, certain aspects provide a circuit for signal amplification including a first amplifier; a first transistor, a gate of the first transistor being coupled to an output of the first amplifier and a drain of the first transistor being coupled to an output node of circuit; a first resistive element coupled between a first input node of the circuit and an input of the first amplifier; a second amplifier; a second transistor, a gate of the second transistor being coupled to an output of the second amplifier and a drain of the second transistor being coupled to the output node of circuit; and a second resistive element coupled between a second input node of the circuit and an input of the second amplifier.

The present application provides a capacitance detection circuit, which could reduce the influence of screen noise on capacitance detection. The capacitance detection circuit includes: an amplification circuit connected to the capacitor to be detected, and configured to convert a capacitance signal of the capacitor to be detected into a voltage signal, the voltage signal being associated with the capacitance of the capacitor to be detected; and a control circuit connected to the amplification circuit, and configured to control an amplification factor of the amplification circuit to be a first amplification factor in a first period, and to control the amplification factor of the amplification circuit to be a second amplification factor in a second period, where noise generated by the screen in the first period is less than noise generated by the screen in the second period, and the first amplification factor is greater than the second amplification factor.

A circuit includes a binary weighted divider having a first set of switches coupled in series between an input node and a feedback node. The first set of switches is configured to set a feedback voltage at the feedback node in response to activating or deactivating respective switches in the first set of switches. A set of compensation switches is coupled to the first set of switches. The set of compensation switches is configured to reduce resistance of one or more of the respective switches in the first set of switches that are activated by activating one or more switches in the set of compensation switches to provide one or more respective parallel current paths for each of the switches in the first set of switches that are activated.

Amplifier systems for measuring a wide range of current are provided herein. In certain embodiments, an amplifier system includes a controllable sensing circuit, a first amplifier including an output configured to drive a device under test (DUT) through the controllable sensing circuit, and a second amplifier including an input coupled to the controllable sensing circuit and operable to generate a measurement signal indicating an amount of measured current of the DUT. The amplifier system further includes a control circuit operable to control a configuration or mode of the controllable sensing circuit suitable for a particular type of DUT.

A variable gain amplifier circuit is disclosed. In one embodiment, an amplifier circuit includes first and second stages. Each stage includes one or more inverter pairs, with one inverter of each pair coupled to receive an inverting component of a differential signal and the other inverter of the pair coupled to receive a non-inverting component. The first stage receives a differential input signal and produces an intermediate differential signal. The second stage receives the intermediate differential signal and produces a differential output signal, the differential output signal being an amplified version of the differential input signal.

An oscillation apparatus includes a correction circuitry including a first amplifier and a second amplifier, and an oscillation circuitry. The first amplifier amplifies a difference between a first voltage having a first temperature characteristic and a second voltage having a second temperature characteristic different from the first temperature characteristic to generate a third voltage having a third temperature characteristic different from both the first temperature characteristic and the second temperature characteristic. The second amplifier amplifies a difference between a sum of the second voltage and the third voltage, and, a feedback voltage, to generate a fourth voltage which corrects an oscillation frequency of an oscillation voltage. The oscillation circuitry outputs the oscillation voltage controlled in frequency based on the fourth voltage.

An example apparatus includes: a first voltage source, a first amplifier having a noninverting input adapted to be coupled to a photodiode anode and coupled to the first voltage source, an inverting input adapted to be coupled to a photodiode cathode, and an output, a first resistor coupled to the first amplifier inverting input and to the first amplifier output, a first capacitor coupled to the inverting input of the first amplifier and the first amplifier output, and a second voltage source different from the first voltage source. There is a second amplifier having a noninverting input, an inverting input and an output. The noninverting input is coupled to the output of the first amplifier, the inverting input is coupled to the second voltage source, and there is a second resistor coupled to the inverting input and the output of the second amplifier.