A Novel Approach to Implementing On-Chip Synchronous Detection for CMOS Optical Detector Systems

A phase-switching approach suppresses the need to employ a precise multiplier for synchronous demodulation. An improved solution for implementing on-chip synchronous detection consists of using a switched-phase amplifier, which combines pre-amplification and phase-switching operations. This enables circuit simplification, voltage lowering, and power and surface savings. A detector-associated circuit realising pre-amplification and synchronous demodulation is proposed. It includes a transimpedance amplifier, a switched-phase amplifier and a low-pass filter. All these building blocks are designed to operate under a minimum supply of 2 V, using a double-poly, 0.8-m CMOS process. The designed circuit is to be integrated with a CMOS optical detector for portable applications. System-level simulations (including the detector model) are performed to validate the system operation, and to estimate performances. The sensitivity of the system in terms of minimum detectable optical signal (which is synchronously modulated) is evaluated to be 2.2 10^–14 W/mm² in normal measuring conditions.  

光电检测前置放大电路设计及稳定性分析

光电检测前置放大电路的设计直接影响整个检测电路的性能。选择光电二极管在光伏模式下工作，使用低输入偏置电流和低噪声放大器，设计了光电检测前置放大电路，重点分析了转换电路的稳定性，给出了转换电路元器件参数选择的依据。电路在实际应用中取得了良好的效果。  

光电探测方法研究

为了获取光电检测系统中的更强光信号,提高光电探测效率及信噪比,分析了光电直接探测与相干探测系统原理及特征,针对光电探测系统中探测器接收的光信号微弱问题,提出了光前置放大探测与平衡探测方法及信噪比改善措施.理论分析表明,光前置放大探测与平衡探测具有更低的光强度响应.  

电磁超声换能器的前置放大电路设计

针对电磁超声换能器接收线圈接收到的信号通常十分微弱的特点,设计了分别应用NJM4580和AD620的微小信号放大电路,并通过美国国家仪器公司的Multisim 10软件中波特图仪和示波器对两前置放大电路进行虚拟仿真,并对仿真结果进行比较,验证了应用AD620的放大电路在微小信号放大上不仅电路构成简单,而且在放大性能上更加优于应用NJM4580运算放大器构成的差分级联放大电路。  

利用Multisim和华大九天EDA工具进行比较器设计

采用EDA仿真软件Multisim对预放大与判断电路进行仿真测试，利用此软件的仿真分析功能测试电路的电压传输特性曲线。同时，借助华大电子九天EDA工具（Zeni），设计预放大与判断电路的芯片版图，进而对版图仿真。