Image Processor and RISC MCU Embedded Single Chip Fingerprint Sensor

Abstract

In this paper, we propose a single chip fingerprint sensor with the algorithm processor and 16-bit MCU. The algorithm processor is a logic circuit that implements the GABOR filter and the THINNING step, which occupies 80% of the fingerprint image processing time. The rest of the algorithm is processed by embedded 16-bit MCU with small circuit volume, so all steps of the algorithm can be processed on the single chip without an external CPU. The capacitive sensing circuit was designed by applying the parasitic-insensitive integrator with the variable clock generator. The function was verified by Cadence Spectre for a 1-pixel sensor scheme and RTL and post simulation for digital blocks synthesized by Synopsys Design Compiler in 180n 2-poly 6-metal CMOS (complementary metal–oxide–semiconductor) process. The layout is done by automatic P&R for the full chip in a 96 × 96 pixel array. The chip area is 5010 μm × 5710 μm (28.61 mm2) and the gate count is 2,866,700. The result is compared with a conventional one. The proposed scheme can reduce the processing time by 57%.