CMOS图像传感器中可编程增益放大器的设计

Design of a Programmable Gain Amplifier for CMOS Image Sensor

设计了一个低功耗宽摆幅全差分开关电容可编程增益放大器（PGA）。该放大器可实现近似1 dB步进,0～15 dB增益变化范围,可用于CMOS图像传感器。提出了一种可调补偿电容的运算跨导放大器（OTA）,通过补偿电容调节OTA带宽,大大降低了PGA的功耗。采用TSMC3.3 V 0.18μm工艺,在20 MSPS采样率下,使用Hspice仿真。结果显示,电路功耗仅为7 mW,输出摆幅为轨至轨,精度为12位。

A low power high swing fully differential switched-capacitor programmable gain amplifier（PGA） was designed to process a fully differential input signal from CMOS image sensor（CIS） interface.The PGA had a dynamic range of 16 dB with roughly 1 dB step and 12-bit resolution.An operational transconductance amplifier（OTA） with variable compensation capacitor to adjust its bandwidth was proposed,which greatly reduced PGA power.The PGA was designed and simulated in TSMC＇s 0.18 μm mixed-signal CMOS process with 3.3 V supply.Hspice simulation showed that the circuit had a rail-to-rail output swing and it dissipated 7 mW of power at 3.3 V and 20 MSPS