Home    Bloggers    Blogs    Article Archives    Messages    About Us
Tw  |  Fb  |  In  |  Rss
Dennis Feucht

# Differential-Amplifier Common-Mode Rejection Measurements, Part 1: Differential Amplifier CM Principles

D Feucht
6/24/2015 5:39:53 PM
User Rank
Blogger
Re: Expression for common mode
Yee Huan Xiansheng,

Indeed, you are correct. The CM gain definition is correct in the text above the equation, but for it to be an average the arithmetic operation needs to be + not -. Thanks for catching that embarrassingly obvious error!

50%
50%
yeehuan
6/23/2015 3:51:02 AM
User Rank
Newbie
Re: Expression for common mode
I agree with Guy...The second equation in the article which calculates the common mode input voltage shows: (V_I+ - V_I-)/2...Shouldn't it be (V_I+ + V_I-)/2 instead?

50%
50%
D Feucht
6/17/2015 9:05:39 PM
User Rank
Blogger
Re: Expression for common mode
Guy,

Which equation are you referring to? None of the equations I find in the article have negative signs out front.

0%
100%
Guy Noir
6/17/2015 11:38:14 AM
User Rank
Newbie
Expression for common mode
Shouldn't the equation for common mode have a plus sign rather than a minus?

100%
0%
More Blogs from Dennis Feucht
The Analog of Real-Time Software
Previously we looked at the electronics and sensors involved in data acquisition systems (DASs). Now we look at what to do with the raw ADC data once it is acquired.
This is a tutorial presentation of principles of instrumentation that is typically multi-channel, medium to high resolution (12 to 20 bits) and relatively slow - slower than oscilloscopes in sample rate
Continuing the chat from last time, we turn now to a circuit-related topic, that of current waveforms. The typical converter input waveform is shown with a static (dc) component and a ripple (ac) component
Semiconductor companies have now had fully-differential amplifiers in their product lines for a few years, though these amplifiers have been in leading-edge electronics for decades. These diff-amps are differential not only at their input but also at their output, doubling output range.
flash poll