A VLSI IMPLEMENTATION FOR HIGH SPEED AND HIGH SENSITIVE FINGERPRINT SENSOR USING CHARGE ACQUISITION PRINCIPLE

In this proposed work, we have implemented 80X64 Array high sensitive fingerprint sensor with capacitive charge acquisition principle. It used charge transfer acquisition principle for sensing the change in capacitance. The electrode capacitance is charged to the stable reference voltage. The charge is then transferred to a known capacitor referred to as the sampling capacitor (CS). This sequence is repeated until the voltage on the CS capacitor reaches an internal reference voltage. The number of transfers required to reach the threshold depends on the size of the electrode capacitance and represents its value. The ADC resolution has been increased and thus to ensure stable operations, number of transfers needed to reach the threshold is adjusted by IIR Filter which compensates for environmental changes such as temperature, power supply, moisture, and surrounding conductive objects. The operation is validated by TSPICE for one-pixel and RTL simulation by Xilinx ISE including logic synthesis for the full chip design on condition of 0.18μm typical CMOS process and 1.8V power.