Implementation of TDI based digital pixel ROIC with 15 mu m pixel pitch

Official URL: http://dx.doi.org/10.1117/12.2224766

A 15um pixel pitch digital pixel for LWIR time delay integration ( TDI) applications is implemented which occupies one fourth of pixel area compared to previous digital TDI implementation. TDI is implemented on 8 pixels with oversampling rate of 2. ROIC provides 16 bits output with 8 bits of MSB and 8 bits of LSB. Pixel can store 75 M electrons with a quantization noise of 500 electrons. Digital pixel TDI implementation is advantageous over analog counterparts considering power consumption, chip area and signal-to-noise ratio. Digital pixel TDI ROIC is fabricated with 0.18um CMOS process. In digital pixel TDI implementation photocurrent is integrated on a capacitor in pixel and converted to digital data in pixel. This digital data triggers the summation counters which implements TDI addition. After all pixels in a row contribute, the summed data is divided to the number of TDI pixels( N) to have the actual output which is square root of N improved version of a single pixel output in terms of signal-to-noise-ratio (SNR).