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研究了一种应用于1 024×1 024CMOS图像传感器中的温度计码电容阵列型可编程增益放大器(PGA)。该PGA采用开关电容阵列结构,通过改变输入与反馈电容值,实现了0～18dB的增益;同时,该PGA具有结构简单、电容阵列面积小、带宽大和反馈系数大等特点,其增益带宽50MHz、总谐波失真(THD)小于50dB。该PGA的信号处理能力完全满足12MHz速率、69dB动态范围CMOS图像传感器内部集成ADC对模拟输入信号的要求。
A kind of thermometer code capacitor array programmable gain amplifier (PGA) used in 1 024 × 1 024 CMOS image sensor was studied. The PGA adopts a switched capacitor array structure and achieves a gain of 0~18 dB by changing input and feedback capacitor values. Meanwhile, the PGA has the advantages of simple structure, small capacitor array area, large bandwidth and large feedback coefficient, and has a gain bandwidth of 50 MHz, Total harmonic distortion (THD) is less than 50dB. The signal processing capabilities of the PGA fully meet the 12MHz rate, 69dB dynamic range CMOS image sensor integrated analog to digital input signal requirements.