A quasi-differential C-V convertor for touch screen panel controller IC

A capacitance to voltage convertor for a five-inch touch screen panel is designed. In this paper, a new quasidifferential buffer is proposed to be robust with respect to display noise and highly area efficient. The measurement results show that the signal-to-noise ratio is 29.8 dB when evaluated with a 3.7-inch add-on touch screen panel and LCD display. The proposed circuit, fabricated via TSMC 0.18 um 1P6M CMOS process technology with embedded flash memory and total chip areas, is 2.8 mm × 3.2 mm, including digital block. It consumes 17.8 mW of power from a 3.3 V supply at an 80 Hz scan rate for normal operation, and 2.6 mW at 20 Hz for idle operation.