简易数字控制高速差分探头设计

Design of Simple Digital Control High-Speed Differential Probe

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。该差分探头的设计采用可控增益芯片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^20 MHz频带内的增益起伏不大于1 d B,完全满足一般高校电工电子实验要求。

An active high speed differential oscilloscope probe is designed, and realizes the function of differential input and single output. The differential probe uses a controlled gain chip VCA822, and it can turn double end sig- nal to single end signal, and it can also realize the setting function of one time and ten times. The design of differen- tial mode signal source uses high-speed and low-noise total differential operational amplifier LMH6550, and realiz- es 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-20 MHz band is less than 1 dB, so it fully meets the general requirements of electrical and electronic experiments in Colleges and universities.