一种宽动态范围跨阻放大器的设计

Design of Transimpedance Amplifier with Wide Dynamic Range

针对光电探测器的光电流信号弱、变化范围大的特点,设计了一种全新的检测光电流信号的跨阻放大器(TIA)电路结构,其检测电流信号范围为1.6μA^1.6mA,动态电流检测范围达到60dB。通过在电路内部设计出两个增益可调、增益段不同的TIA,分别处理光电流的小电流段(1.6~50μA)和大电流段(50μA^1.6mA),增益可调范围为56~96dBΩ;通过外置输出电压饱和检测信号,选择所需工作的TIA及其增益段。该电路采用0.18μm标准CMOS工艺的PDK进行电路设计、版图设计和仿真验证等。测试结果表明:在检测电流为1.6μA时,输出电压为95mV;检测电流为1.6mA时,输出电压为915mV,与仿真结果相一致。电路瞬态特性良好,上升时间为5~10ns,3.3V电压下功耗小于2mW,各指标满足设计要求。

Aiming at the characteristics of weak photo-current signal and large variation range of photodetector,an all new structure of transimpedance amplifier（TIA）for detecting photo-current signal is designed in this paper.The detection current signal ranges from 1.6μA to1.6mA,and the dynamic current detection ranges is up to 60 dB.The design principle of this circuit structure is to process the small current section（1.6~50μA）and the large current section（50μA^1.6mA）for the photocurrent respectively by designing two TIA with adjustable gain and different gain sections in the circuit,and the gain is adjustable from 56dBΩto 96dBΩ.Through the external output voltage saturation detection signal,we can select the desired TIA and its gain section.The PDK fabricated by 0.18μm standard CMOS process is used for the circuit design,layout design and simulation verification.The test results show that the output voltage is 95 mV at the current of 1.6μA and the output voltage is 915 mV at the current of1.6mA,which are in accordance with the simulation results.The transient characteristic of the circuit is good,the rise time is 5~10ns,and the static power consumption is 1~2mW at the voltage of 3.3V.The indexes meet the design requirements.