An instrumentation amplifier that includes input capacitance cancellation is provided. The architecture includes programmable capacitors between the input stage and a current feedback loop of the instrumentation amplifier to cancel input capacitances from electrode cables and a printed circuit board at the front end. An on-chip calibration unit can be employed to calibrate the programmable capacitors and improve the input impedance.

A balanced differential transimpedance amplifier with a single-ended input operational over a wide variation in the dynamic range of input signals. A threshold circuit is employed to either or a combination of (1) generate a varying decision threshold to ensure a proper slicing over a wide range of input current signal levels; and (2) generate a bias current and voltage applied to an input of a transimpedance stage to cancel out a dependence of the transimpedance stage voltage input on input current signal levels.

An operational amplifier comprises: a first amplifier stage 4 comprising a first differential pair of transistors 8, 10 arranged to receive and amplify a differential input signal 18, 20 thereby providing a first differential output signal 22, 24; and a second amplifier stage 6 comprising a second differential pair of transistors 26, 28 arranged to receive and amplify the first differential output signal 22, 24 thereby providing a second differential output signal 38, 40.

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.

Disclosed herein is a method including sinking current from a pair of input transistors of a differential amplifier while sourcing more current to the pair of input transistors than is sunk. The method further includes generating a pair of input differential signals using a pair of input voltage regulators, and amplifying a difference between the pair of input differential signals to produce a pair of differential output voltages, using the differential amplifier. The method also includes amplifying the pair of differential output voltages using at least one voltage gain amplifier, and generating control signals for current sources that source the current to the pair of input transistors of the differential amplifier, from the pair of differential output voltages after at least amplification.

A capacitive amplifier device and technique for mitigating the perturbation within the switchable terminals of a feedback capacitor which is produced by the switching activity performed as part of the device's operation. The capacitive amplifier contains feedback components which can be switched without producing significant kickback or poorly behaved transitions due to the inclusion of at least one dedicated circuit. The dedicated circuit is a kickback limiter circuitry which is connected to a switchable node and is designed to reduce the kickback. The technique for reducing the kickback produced can be achieved by connecting and activating the kickback limiter circuitry.

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Disclosed herein is a method including sinking current from a pair of input transistors of a differential amplifier while sourcing more current to the pair of input transistors than is sunk. The method further includes generating a pair of input differential signals using a pair of input voltage regulators, and amplifying a difference between the pair of input differential signals to produce a pair of differential output voltages, using the differential amplifier. The method also includes amplifying the pair of differential output voltages using at least one voltage gain amplifier, and generating control signals for current sources that source the current to the pair of input transistors of the differential amplifier, from the pair of differential output voltages after at least amplification.

A shaper circuit includes a first amplifier including an input and an output, the input being configured to receive an input signal, which includes one or more current pulses, a feedback component coupled to the output and to the input of the first amplifier thereby forming a feedback loop of the first amplifier, and an RC component coupled to the output of the first amplifier and to a reference potential terminal. Therein the shaper circuit is configured to provide an output signal as a function of the input signal, the output signal including one or more voltage pulses, and the RC component is configured to largely cancel a low frequency pole of the feedback loop of the first amplifier.

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.

An amplifier circuit includes a voltage-to-current conversion circuit and a current-to-voltage conversion circuit. The voltage-to-current conversion circuit generates a current signal according to an input voltage signal, and includes an operational transconductance amplifier (OTA) used to output the current signal at an output port of the OTA. The current-to-voltage conversion circuit generates an output voltage signal according to the current signal, and includes a linear amplifier (LA), wherein an input port of the LA is coupled to the output port of the OTA, and the output voltage signal is derived from an output signal at an output port of the LA.