FIELD OF THE DISCLOSURE

This document relates generally to integrated circuits and more particularly, but not limited to, gain stage circuits.

BACKGROUND

An input signal can be applied to a gain stage to adjust a level of the input signal. For example, the gain stage can amplify or attenuate the input signal. A gain stage can receive an input voltage and generate an output voltage. For example, an instrumentation amplifier can include three operational amplifiers coupled together in two stages to output a voltage that is an amplified or attenuated version of a received input signal.

The output voltage of the gain stage can be applied to a subsequent circuit. For example, a voltage-based analog-to-digital converter circuit can be coupled with receive the output voltage of the gain stage.

SUMMARY OF THE DISCLOSURE

This disclosure describes various techniques to allow an output current from a gain stage, such as an instrumentation amplifier, to be applied directly from a current output node to an input node of a current input of a subsequent circuit, such as an ADC circuit.

In some aspects, this disclosure is directed to a circuit comprising a gain stage including: an input node to receive an input signal; a first operational amplifier stage coupled between the input node and a current output node, the current output node to provide a current output; a current mirror stage coupled with an output of the first operational amplifier stage, the current output node coupled with the current mirror stage; and an analog-to-digital converter (ADC) circuit having an input node coupled with the current output node of the gain stage, the input node to receive a current input.

In some aspects, this disclosure is directed to a method comprising: receiving an input signal; applying, using a gain stage, a gain to the input signal to adjust a level of the input signal; outputting, using a current output node of the gain stage, a current representing the adjusted input signal; and applying the current representing the adjusted input signal to an input node of an analog-to-digital converter (ADC) circuit having an input node coupled with the current output node of the gain stage, the input node to receive a current input.

In some aspects, this disclosure is directed to a gain stage including: an input node to receive an input signal; a first operational amplifier stage coupled between the input node and a current output node, the current output node to provide a current output; a current mirror stage coupled with an output of the first operational amplifier stage, the current output node coupled with the current mirror stage; a second operational amplifier stage coupled between the current mirror stage and a voltage output node, the voltage output node to provide a voltage output; a first analog-to-digital converter (ADC) circuit having an input node coupled with the current output node of the gain stage, the input node to receive a current input; and a second ADC circuit having a voltage-based input node coupled with the voltage output node of the gain stage.

