A low-distortion and wide dynamic range CMOS imager for wireless capsule endoscopy

A low-distortion and wide dynamic range (DR) CMOS imager for wireless capsule endoscopy is designed in a 0.35um CMOS process. The new pixel circuit can expand the DR, and improve the signal-to-noise ratio (SNR) at the same time, with a partial pixel-level digitization scheme. The new pixel is also designed to enable digital self-calibration to compensate for the analog non-idealities in the pixel circuit, so as to suppress the distortion. With a digital signal processor (DSP) decoder at the receiver side, low distortion and wide DR image can be recovered. SPICE simulation results show that SNDR of the recovered image can reach 61.26dB after calibration. The hardware cost of the decoder is moderate.