Patent ID: 8330735

Claim:
A capacitive touch circuit, comprising: a single comparator having a first input terminal, a second input terminal, and an output terminal; a reference voltage control unit electrically connected to the second input terminal, wherein the reference voltage control unit comprises: a high level voltage source; a low level voltage source; and a voltage switching controller electrically connecting either the high level voltage source or the low level voltage source to the second input terminal of the single comparator according to an output signal of the single comparator; a resistance adjusting unit electrically connected to the first input terminal of the single comparator; a delay unit electrically connected to the output terminal of the single comparator for filtering out the transition of the output signal, wherein the delay unit comprises: a delay time selector for deciding a delay time length according to the duration of the transition of the output signal of the single comparator; and a delay time adjuster for delaying the start of the transition of the output signal of the single comparator according to the delay time length; and a relaxation oscillation control unit electrically connected to the resistance adjusting unit, the delay unit, and the reference voltage control unit, wherein the relaxation oscillation control unit outputs a relaxation oscillation signal, the relaxation oscillation signal is fed into the first input terminal of the single comparator, and the frequency of the relaxation oscillation signal varies according to the resistance set by the resistance adjusting unit.