Low-noise and low power CMOS photoreceptor using split-length MOSFET

Abstract : This paper presents the design of a low-power and low-noise CMOS photo-transduction circuit. We propose to use the new technique of composite transistors for noise reduction of photoreceptor in the subthreshold by exploiting the small size effects of CMOS transistors. Several power and noise optimizations, design requirements, and performance limitations relating to the CMOS photoreceptor are presented. This new structure with composite transistors ensures low noise and low power consumption. The CMOS photoreceptor, implemented in a 130 nm standard CMOS technology with a 1.2 V supply voltage, achieves a noise floor of 2μV/⎷Hz within the frequency range from 1 Hz to 10 kHz. The current consumption of the CMOS photoreceptor is 541 nA. This paper shows the need for the design of phototransduction circuit at low voltage, low noise and how these constraints are reflected in the design of CMOS vision sensor.