Patent ID: 8674960
Filing Date: 2014-03-18
Classification: G06F,H03K

Abstract:
1. A detector circuit of a capacitive touch panel having a plurality of traces, the detector circuit comprising: a sample-and-hold circuit for sampling a trace voltage of a selected one of the plurality of traces to generate a sampled voltage; a successive approximation register and control circuit for providing a threshold digital code and a successive approximation digital code, and providing a pre-conversion signal when beginning to convert the sampled voltage; a digital-to-analog converter for converting the threshold digital code into a threshold voltage or converting the successive approximation digital code into a comparison voltage; a multiplexer connected between the successive approximation register and control circuit and the digital-to-analog converter, for providing either the threshold digital code to the digital-to-analog converter in response to the pre-conversion signal, or the successive approximation digital code to the digital-to-analog converter at the other time; and a comparator connected to the digital-to-analog converter and the sample-and-hold circuit for comparing the sampled voltage with the threshold voltage or the comparison voltage to generate a comparison result for the successive approximation register and control circuit; wherein if the sampled voltage is lower than the threshold voltage, the successive approximation register and control circuit asserts an abortion signal to abort sensing of the selected trace; otherwise, the successive approximation register and control circuit carries out successive approximation on the trace voltage for the selected trace.