A 128-Stage Analog Accumulator for CMOS <newline/>TDI Image Sensor

A Low Power Digital Accumulation Technique for Digital-Domain CMOS TDI Image Sensor

“…Additionally, due to the incompatibility with the CMOS process, the CCD could not integrate with other functions on the same chip with the sensor [4]. In recent years, TDI image sensors implemented with the CMOS process have been reported [5,6,7,8,9,10,11,12,13,14]. Compared with the CCD, CMOS TDI image sensors could successfully integrate various analog and digital circuits as an on-chip camera [4].…”

“…There are typically three kinds of accumulation methods: charge-domain accumulation scheme [5,6,7,8], analog-domain accumulation scheme [9,10,11] and digital domain accumulation scheme [12,13,14] for CMOS TDI image sensors. In the charge-domain accumulation scheme, the noiseless accumulation enables good SNR.…”

“…However, the charge transfer efficiency and full well capacity, which strongly depend on process, limit its momentum of development [6,7]. With respect to the analog-domain accumulation scheme, the generated signals from pixels are firstly accumulated by the analog accumulator, and then the accumulated result is quantized by column analog-to-digital converter (ADC) [9,10]. Because the maximum accumulated voltage depends on the supply voltage, the dynamic range of the analog-domain CMOS TDI image sensor is limited by the supply voltage [9,10].…”

“…With respect to the analog-domain accumulation scheme, the generated signals from pixels are firstly accumulated by the analog accumulator, and then the accumulated result is quantized by column analog-to-digital converter (ADC) [9,10]. Because the maximum accumulated voltage depends on the supply voltage, the dynamic range of the analog-domain CMOS TDI image sensor is limited by the supply voltage [9,10]. Since the analog memory cell of the analog accumulator is implemented with capacitors, the accumulator area is considerably large [9,10].…”

“…Because the maximum accumulated voltage depends on the supply voltage, the dynamic range of the analog-domain CMOS TDI image sensor is limited by the supply voltage [9,10]. Since the analog memory cell of the analog accumulator is implemented with capacitors, the accumulator area is considerably large [9,10]. In the digital domain accumulation scheme, the outputs of pixels are firstly quantized by column ADC, and then the corresponding digital results are added together by the digital accumulator [14].…”