作为激光近炸引信中探测与目标识别核心元件的光电探测器,其性能取决于光电二极管和相应的放大电路.针对引信、制导应用对光电探测器的要求,提出一种新型高增益、大带宽跨阻放大器设计.该跨阻放大器由两级放大电路构成,第1级由两个对称的RGC(Regulated Cascode)结构组成,消除光电二极管漏电流对直流工作点影响,隔离光电二极管寄生电容提升工作带宽;第2级放大电路由3个级联的反相放大器构成,是跨阻放大器的主要增益级;最后以射级跟随器输出,为后续系统提供足够的电压摆幅.该电路基于SMIC 0.35μm标准CMOS工艺设计,仿真结果表明:跨阻增益为110.2 dBΩ,带宽为46.7 MHz,40 MHz处的等效输入噪声电流低至1.09 pA/Hz,带宽内等效输出噪声电压为5.37 mV.测试结果表明,跨阻放大器增益约为109.3 dBΩ,输出电压信号上升时间约为7.8 ns,等效输出噪声电压大小为6.03 mV,功耗约为10 mW,对应芯片面积为1560μm×810μm.%The performance of photoelectric detectors,as the core element for detection and object identification of laser proximity fuse,depends on the photodiode and corresponding amplifier circuit. Aiming at the requirement of fuse and guidance application, a kind of high gain and high bandwidth TIA is proposed. The TIA consists of two-stage amplifier. The first stage is composed of two symmetrical Regulated Cascodes which eliminate the influence of photodiode's leakage current on DC Operating point and insulate the parasitic capacitance of photodiode to increase the bandwidth of TIA. The second stage consists of three cascade current reuse inverter which is used as the main gain stage. As the output stage, emitter follower is used to provide enough voltage swing for following system. The circuit design is based on SMIC 0.35 μm standard CMOS process. The simulating results indicate that the transimpedance gain is 110.2 dBΩand the bandwidth is 46.7 MHz. At the frequency of 40 MHz the equivalent input noise is as low as 1.09 pA/ Hz and the whole equivalent output noise voltage is 5.37 mV within the frequency bandwidth. Testing results indicate that the transimpedance gain is 109.3 dBΩ,the output rise time is 7.8 ns,the e-quivalent output noise voltage is 6.03 mV,and the total power dissipation is less than 10 mW. The die size is 1560μm×810 μm.
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