Abstract
The novel pixel structures and their corresponding readout circuit design for image sensors in commercial SiGe BiCMOS technologies are presented in this work. Unlike conventional CMOS imagers which have to sense the pixel voltage drop after some integration time, the new pixel directly outputs the sensed photo-current to a natural logarithmic column amplifier for wide dynamic range I-to-V conversion. The pixel structure includes a photo-detector made of SiGe BC diode and a row select switch only. Samples fabricated in standard TSMC 0.35μm SiGe BiCMOS technology verified the feasibility of the design. Along with the column amplifier made of SiGe HBT’s, the imager exhibits a very wide sensing dynamic range of at least 132.2 dB(range of photocurrent is 10pA~40.7uA) and a sensitive detection for low illuminance down to 0.01 lux.