Title :
A fingerprint sensor based on the feedback capacitive sensing scheme
Author :
Tartagni, Marco ; Guerrieri, Roberto
Author_Institution :
Dipt. di Elettronica Inf. e Sistemistica, Bologna Univ., Italy
fDate :
1/1/1998 12:00:00 AM
Abstract :
This paper introduces a single-chip, 200×200-element sensor array implemented in a standard two-metal digital CMOS technology. The sensor is able to grab the fingerprint pattern without any use of optical and mechanical adaptors. Using this integrated sensor, the fingerprint is captured at a rate of 10 F/s by pressing the finger skin onto the chip surface. The fingerprint pattern is sampled by capacitive sensors that detect the electric field variation induced by the skin surface. Several design issues regarding the capacitive sensing problem are reported and the feedback capacitive sensing scheme (FCS) is introduced. More specifically, the problem of the charge injection in MOS switches has been revisited for charge amplifier design
Keywords :
CMOS integrated circuits; arrays; capacitance measurement; compensation; electric charge; electric sensing devices; feedback; fingerprint identification; mixed analogue-digital integrated circuits; switched capacitor networks; 0.7 micron; MOS switches; charge amplifier design; charge injection; electric field variation; feedback capacitive sensing scheme; fingerprint pattern; fingerprint sensor; integrated sensor; single-chip sensor array; skin surface; two-metal CMOS technology; CMOS technology; Capacitive sensors; Fingerprint recognition; Fingers; Mechanical sensors; Optical feedback; Optical sensors; Pressing; Sensor arrays; Skin;
Journal_Title :
Solid-State Circuits, IEEE Journal of
