Title :
Analysis of Dynamic Range, Linearity, and Noise of a Pulse-Frequency Modulation Pixel
Author :
Tsai, Tsung-Hsun ; Hornsey, Richard
Author_Institution :
Dept. of Comput. Sci. & Eng., York Univ., Toronto, ON, Canada
Abstract :
A complete pulse-frequency modulation (PFM) pixel design analysis and noise measurement for CMOS image sensor applications are presented. This work investigates the design parameters such as dynamic range (DR), signal linearity, and comparator characteristics. The design strategies for wide DR imaging are addressed in detail, and signal linearity is analyzed by considering the analog circuit parameters. The temporal noise is also measured to understand the design tradeoffs of the PFM pixels. The analysis is executed by performing HSPICE simulation and practical pixel measurements. The technology used by the measured pixel is a 0.18-μm one-poly six-metal CMOS process. According to the results, a PFM pixel using the submicrometer CMOS process has a DR of 130-160 dB, and the cost of reaching a higher signal linearity or lower noise floor is the loss of frame rate. In addition, the bandwidth of the comparator can be extended to improve sensor linearity.
Keywords :
CMOS image sensors; comparators (circuits); noise measurement; pulse frequency modulation; CMOS image sensor application; DR parameter; HSPICE simulation; PFM pixel design analysis; analog circuit parameter; comparator bandwidth; comparator characteristics; dynamic range parameter; frame rate loss; gain 130 dB to 160 dB; noise floor; one-poly six-metal CMOS process; practical pixel measurement; pulse-frequency modulation pixel design analysis; sensor linearity; signal linearity; size 0.18 mum; submicrometer CMOS process; temporal noise measurement; Dynamic range; Imaging; Lighting; Linearity; Noise; Photodiodes; Transistors; CMOS image sensor; dynamic range (DR); pixel; pulse-frequency modulation (PFM); signal linearity; temporal noise;
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2012.2205690
