Apparatus and method for reducing amplifier feedback capacitor with bypass amplification stage

Abstract

A touchscreen controller includes a set of transmitters for generating transmit signals applied to electrically-conductive transmit lines of a touchscreen panel, and a set of receivers configured to receive the signals via electrically-conductive receive lines that are capacitively coupled to the transmit lines. Each receiver includes an integrator to integrate the received current signal to generate an output voltage used for determining a location, if any, of a finger or object touching the panel. The integrator includes input and output amplification stages, and a feedback capacitor coupled between an input and output of the cascaded amplification stages. The capacitance of the feedback capacitor is configured so that the integrator achieves a desired rejection of a received jammer current signal. To reduce the size of the feedback capacitor, a bypass amplification stage is provided to steer away some of the input jammer current from the input of the integrator.

Dependencies are inferred from the claim text.