An 8/4-bit reconfigurable digital pixel array with on-chip non-uniform quantizer

A CMOS digital pixel sensor (DPS) with reconfigurable coding (8/4-bit) and spatial (32 /spl times/ 32/64 /spl times/ 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 0.35/spl mu/m n-well standard process.