Title :
An 8/4-bit reconfigurable digital pixel array with on-chip non-uniform quantizer
Author_Institution :
Dept. of Electr. & Electron. Eng., Hong Kong Univ. of Sci. & Technol., Kowloon, China
Abstract :
A CMOS digital pixel sensor (DPS) with reconfigurable coding (8/4-bit) and spatial (32 × 32/64 × 32) resolutions is proposed in this paper. The sensor is based on time domain coding which converts the photocurrent into an inversely proportional pulse width (PWM) signal. The 8-bit conversion mode is used for high quality imaging while the 4-bit conversion mode provides a shorter conversion time and a 2-fold increase in spatial resolution. In order to overcome the nonlinearity introduced in the time domain PWM coding, a linearization procedure based on nonuniform time domain quantizer is proposed. The reconfiguration features of the imager are demonstrated through experimental results obtained from a prototype designed using 1-poly, 5 metal CMOS 0.35μm n-well standard process.
Keywords :
CMOS image sensors; integrated circuit design; pulse width modulation; 0.35 micron; 4 bit; 4-bit conversion mode; 8 bit; 8-bit conversion mode; CMOS digital pixel sensor; CMOS process; on-chip nonuniform quantizer; photocurrent; proportional pulse width; reconfigurable coding; reconfigurable digital pixel array; reconfigurable spatial resolutions; CMOS image sensors; CMOS process; CMOS technology; Circuits; Image coding; Photodiodes; Pulse width modulation; Space vector pulse width modulation; Spatial resolution; Voltage;
Conference_Titel :
Custom Integrated Circuits Conference, 2005. Proceedings of the IEEE 2005
Print_ISBN :
0-7803-9023-7
DOI :
10.1109/CICC.2005.1568647
