Design of 128x8 Pixel Array Fingerprint Sensor with a Capacitive- Sensing Circuit Technique for Image Enhancement

This paper proposes 128x8 array swipe type fingerprint sensor with a capacitive-sensing technique for image enhancement. The circuit of one pixel includes a pixel level chargesharing and charge pump to replace an ADC. The circuit also adopts the circuit technique that improves quality of dry finger image captured with capacitive fingerprint sensor LSIs. The proper operation is validated by HSPICE for one-pixel and RTL simulation including logic synthesis for a full chip design on condition of 0.35μm typical CMOS process and 3.3V power. The layout is performed by full custom flow for one-pixel and auto P&R for a full chip. The area of a full chip is 0.161mm 2 (9013μm x 1781μm) and the gate count is 303,329. The area of one-pixel is 58 x 58 μm 2 . Pitch is 60 μm and image resolution is 423dpi.