Invention Application
- Patent Title: APPARATUS AND METHOD FOR REDUCING AMPLIFIER FEEDBACK CAPACITOR WITH BYPASS AMPLIFICATION STAGE
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Application No.: US15926728Application Date: 2018-03-20
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Publication No.: US20190294295A1Publication Date: 2019-09-26
- Inventor: Zongyu Dong , Sameer Wadhwa , Shunxi Wang
- Applicant: QUALCOMM Incorporated
- Main IPC: G06F3/041
- IPC: G06F3/041 ; H03F3/21 ; H03F3/45 ; H03F3/213 ; H03F1/02 ; G06F3/044

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.
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