一种用于CMOS图像传感器的高动态范围Sigma-Delta调制器

A High Dynamic Range Sigma Delta Modulater for CMOS Image Sensors

介绍了一种采用Tower 180 nm CMOS工艺设计的高动态范围Sigma-Delta调制器,该调制器用于CMOS图像传感器的高动态范围读出电路。分析了调制器动态范围的主要影响因素,采用基于Cascode反相器的自调零积分器,得到较大的积分器输出摆幅和积分增益。为了降低功耗,加入动态偏置型比较器,使该调制器具有高动态范围和低功耗的优势。加入瞬态噪声的调制器后仿真结果表明,在等效带宽16 kHz内,1.8 V电源电压和4 MHz的采样时钟下,调制器的动态范围为103 dB,功耗仅为356μW。该调制器满足CMOS图像传感器的高动态范围要求。

A high dynamic range Sigma Delta modulator designed by Tower 180 nm CMOS process was presented.The modulator is used in the high dynamic range readout circuit of CMOS image sensor.The main factors affecting the dynamic range of the modulator are analyzed.A self-zeroing integrator based on a Cascode inverter is used to obtain a large output swing and integral gain of the integrator.In order to reduce the power consumption,the dynamic bias comparator is used here,which brings the advantages of high dynamic range and low power consumption.The post simulation results with transient noise show that the dynamic range of the modulator is 103 dB and the power consumption is only 356μW under the equivalent bandwidth of 16 kHz,1.8 V power supply voltage and 4 MHz sampling clock.The modulator meets the high dynamic range requirements of CMOS image sensors.