common mode noise and small signals i have never worked with really small signals before and have a few questions about low level noise i have noticed that the waveform synthesizer that i am using analogic has some relatively large common mode noise on it i am using this synthesizer to null out another transient waveform and am amplifying the difference uv several hundred times the has about mvp p of common mode noise and this tends to make my measurements hard to repeat the noise is not quite in sync with line frequency and on a spectrum analyzer the main component is about hz how can i get rid of the noise when i look at the spectrum using an hp a audio range analyzer the noise goes away the minute i switch to isolation on the input i am guessing the anlayzer has a diff amp on the input since it will read accurately down to dc also if i use a differential amplifier ia to solve the problem how important is it to use one of these shield drivers an amp connected to the shield in sort of a feedback loop to remove trouble caused by different cable capacitances if anyone can suggest a good ic ia for use with transient signals with content from khz to about khz i would appreciate it
