Abstract: An integratable capacitive touch sensing circuit through charge sharing is provided, including a charge sharing circuit, voltage-controlled oscillator, reference frequency generator, switch clock generator and frequency compare circuit; wherein charge sharing circuit further including a sensing capacitor, touch capacitor, share capacitor, charging switch, charge sharing switch and discharging switch, for sharing charge from charged sensing capacitor with discharged share capacitor through charge sharing to accumulate voltage on share capacitor. The capacitance of share capacitor is adjustable for applications generating different sensing capacitance. The charging switch, charge sharing switch and discharging switch are controlled by non-overlapping clocks. Prolonging close duration of charging switch and minimizing close duration of charge sharing switch and discharging switch can minimize interference from ambient noise.

Abstract: An integratable capacitive touch sensing circuit through charge sharing is provided, including a charge sharing circuit, voltage-controlled oscillator, reference frequency generator, switch clock generator and frequency compare circuit; wherein charge sharing circuit further including a sensing capacitor, touch capacitor, share capacitor, charging switch, charge sharing switch and discharging switch, for sharing charge from charged sensing capacitor with discharged share capacitor through charge sharing to accumulate voltage on share capacitor. The capacitance of share capacitor is adjustable for applications generating different sensing capacitance. The charging switch, charge sharing switch and discharging switch are controlled by non-overlapping clocks. Prolonging close duration of charging switch and minimizing close duration of charge sharing switch and discharging switch can minimize interference from ambient noise.

Abstract: An apparatus and method for automatically detecting an audio signal and sending a control signal are provided. The present invention is for automatically detecting an audio signal from a conventional IC, and controlling the power amplifier of the driving speaker or the switch of other external circuit. The apparatus at least includes an audio detection circuit and a reset/delay circuit. The audio detection circuit is connected to an audio signal from a conventional IC to detect the presence of the audio signal. The reset/delay circuit, after receiving an output signal from the audio detection circuit, can either reset the reset/delay circuit, or send a control signal after delaying for a period of time. The apparatus of the present invention can also be integrated into the external circuit, such as a power amplifier, to simplify the control to the external circuit by the conventional IC so as to switch off the external circuit to save power when there is no presence of the audio signal.