Touch sensor circuit with touch screen pen detection

摘要

A touch sensor circuit includes a plurality of drive/receive circuits and a drive signal generation circuit. The drive/receive circuits drive and receive signals from a multi-touch sensor. A drive/receive circuit includes an analog to digital conversion (ADC) circuit and a digital to analog conversion (DAC) circuit. The ADC circuit includes a first input to receive a sensor signal on an electrode of the multi-touch sensor. The sensor signal includes a drive signal component and a receive signal component. The ADC circuit includes a second input to receive an analog reference signal from the drive signal generation circuit. The ADC circuit generates a digital signal based on the analog reference signal and the sensor signal. The DAC circuit converts the digital signal into the drive signal component and the receive signal component is representative of an impedance on the electrode detected and is indicative of a touch proximal to the electrode.