CAPACITIVE TOUCH DEVICE AND EXCITATION SIGNAL GENERATING CIRCUIT AND METHOD THEREOF

摘要

The present invention is related to a capacitive touch device and excitation signal generating circuit and method thereof. The excitation signal generating circuit is connected to multiple sensing traces of the capacitive touch device, and has a storage unit storing at least one set of digital data. Each set of digital data is corresponding to a frequency. The PDM signal generator reads the set of digital data and converts the read set of digital data to a PDM signal according to the frequency of the read set of digital data. The PDM signal is recovered to an analog excitation signal since the PDM signal passes through a current transmission path, which is equivalent to a low pass filter. Therefore, the present invention can decrease a distortion of the sensing signal to increase accuracy of the sensing signal and to save power.

主权项

1. An excitation signal generating circuit of a capacitive touch device, which is used to electronically connected to multiple sensing traces, comprising:
a storage unit storing at least one set of digital data and each of set of digital data corresponding to a frequency; a pulse density modulation (PDM) signal generating circuit connected to the storage unit and the sensing traces to read the set of digital data of the storage unit, converting the read set of digital data to a PDM signal according to the frequency of the read set of digital data and outputting the PDM signal to the sensing traces.