简易数字控制高速差分探头设计

设计了有源高速差分示波器探头，实现了差分输入、单端输出功能。同时，设计了一个用于测试该差分探头的差模信号源。该差分探头的设计采用TI公司提供的共模抑制比可达80dB的可控增益芯片VCA822，实现了双端信号转单端信号以及差分探头1倍和10倍档的设置功能。差模信号源的设计采用了高速和低噪声全差分运算放大器LMH6550，实现了完全对称的差模信号源输出且共模电压可调功能。测量实验证明了本设计系统稳定且差分探头具有高共模抑制比，探头在DC～20MHz频带内的增益起伏不大于1dB，完全满足一般高校电工电子实验要求。

Design of Simple Digital Control High-speed Differential Probe

An active high speed differential oscilloscope probe is designed, and realizes the function of differential input and single output. At the same time, a differential signal source is also designed to test the differential probe. The differential probe uses chip VCA822 (produced by Texas Instruments Incorporated) which provides common mode rejection ratio up to 80dB, and it can turn double end signal to single end signal, and it can also realize the setting function of one time and ten times. The design of differential mode signal source uses high-speed and low-noise total differential operational amplifier LMH6550, and realizes signal source output of fully symmetrical differential mode and adjustable function of common mode voltage. The measurement results show that the design system is stable and the differential probe has high common mode rejection ratio, and its gain fluctuation in DC ~ 20MHz band is less than 1dB, so it fully meets the general requirements of electrical and electronic experiments in Colleges and universities.