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What is Common Mode Rejection Ratio (CMRR) and how to measure it on a high voltage differential probe or differential amplifier. Using the new Rohde & Schwarz MXO4 oscilloscope.
https://www.rohde-schwarz.com/us/products/test-and-measurement/oscilloscopes/rs-mxo-4-oscilloscope_63493-1164992.html
Extended 30min version: https://www.youtube.com/watch?v=4gi2B3LrCww
Differential Probe How It Works: https://www.youtube.com/watch?v=GOlgaEK2Hsk
High Voltage Probe reverse engineering: https://www.youtube.com/watch?v=GOk1BYKSsOI&t=2s
Oscilloscope Standard Deviation noise measurement: https://www.youtube.com/watch?v=G8Qoj3TpO9A
Use coupon code ProbeyMcprobeFace for 15% of the HVP70 differential probe:
https://www.eevblog.com/product/hvp70/
Forum: https://www.eevblog.com/forum/blog/eevblog-1521-how-to-measure-differential-probe-cmrr/
00:00 - What is CMRR?
01:53 - Why twist the wires?
03:26 - Typical CMRR figures
04:51 - How to measure CMRR - The Setup
08:54 - Remote R&S Oscilloscope desktop view & settings
11:22 - Output to input voltage ratio
11:58 - Beware of DC offset
13:36 - Does the 20MHz CMRR measaurement match?
14:02 - Input referred measurement
15:02 - Compensating for the gain
16:29 - Automated Frequency Response Analysis
Support the EEVblog on:
Patreon: http://www.patreon.com/eevblog
Web Site: http://www.eevblog.com
Other channels:
EEVblog2: http://www.youtube.com/EEVblog2
EEVdiscover: https://www.youtube.com/eevdiscover
T-Shirts: http://teespring.com/stores/eevblog
#ElectronicsCreators #CMRR #Tutorial
Stock and Crypto AI Prediction : https://stocksignalslive.com
What is Common Mode Rejection Ratio (CMRR) and how to measure it on a high voltage differential probe or differential amplifier. Using the new Rohde & Schwarz MXO4 oscilloscope.
https://www.rohde-schwarz.com/us/products/test-and-measurement/oscilloscopes/rs-mxo-4-oscilloscope_63493-1164992.html
Extended 30min version: https://www.youtube.com/watch?v=4gi2B3LrCww
Differential Probe How It Works: https://www.youtube.com/watch?v=GOlgaEK2Hsk
High Voltage Probe reverse engineering: https://www.youtube.com/watch?v=GOk1BYKSsOI&t=2s
Oscilloscope Standard Deviation noise measurement: https://www.youtube.com/watch?v=G8Qoj3TpO9A
Use coupon code ProbeyMcprobeFace for 15% of the HVP70 differential probe:
https://www.eevblog.com/product/hvp70/
Forum: https://www.eevblog.com/forum/blog/eevblog-1521-how-to-measure-differential-probe-cmrr/
00:00 - What is CMRR?
01:53 - Why twist the wires?
03:26 - Typical CMRR figures
04:51 - How to measure CMRR - The Setup
08:54 - Remote R&S Oscilloscope desktop view & settings
11:22 - Output to input voltage ratio
11:58 - Beware of DC offset
13:36 - Does the 20MHz CMRR measaurement match?
14:02 - Input referred measurement
15:02 - Compensating for the gain
16:29 - Automated Frequency Response Analysis
Support the EEVblog on:
Patreon: http://www.patreon.com/eevblog
Web Site: http://www.eevblog.com
Other channels:
EEVblog2: http://www.youtube.com/EEVblog2
EEVdiscover: https://www.youtube.com/eevdiscover
T-Shirts: http://teespring.com/stores/eevblog
#ElectronicsCreators #CMRR #Tutorial
This is really great stuff Dave! I loved every bit of it, it's well polished.
I know this doesn't make sense, but I actually prefer looking at the scope from the cameras perspective rather than the screen capture. Wouldn't be the same for a smaller scope, but for this one…
One-of my first projects in electronics as a design tech was to build a common mode amplifier. For the life of I had no idea what there was to achieve expect build an amplifier that had a gain of 1 or less. The cathode follower ! I used an RCA low noise high frequency 6DS4.
I love these kind of videos. They make learn and relearn things I have dealt with for some time. 😎 Thanks and happy 2023 new year. 🥳
Thank you Dave for educating us!
Did I win the scope? I guessed 42 Send to Long Beach, CA. USA, 3rd house on the right. THANK YOU!
Guess you need to put the whole setup in a faraday cage to reject as much noise as possible
Dave, you should make a note that you’re measuring CMRR from input to output (the smaller, the better), while the formulas you show and what you describe display CMRR as the ratio of differential gain to common mode gain (the larger, the better). I can see an astute viewer being confused. Otherwise, great video.
👍Wow, pretty advanced features that you are explaining here! Many thanks.
Merry Christmas
Too late to ask Santa this gorgeous oscilloscope
Why Ch1 changed from 1.75V to 1.80V when changing frequencies? The attenuation in the circuit should be linear, right?
👍 🔥
I’m sorry – I’m just gonna say this subject is hocus Pocus – as well as that gadget measuring it -& that fancy microwave with a funny picture on it. Hocus Pocus.
Good but TOO LONG.
I never got a satisfying answer to what "common mode" noise was. I always saw CM chokes and wondered why they were needed.
My understanding is common mode is simply a signal that it applies to all input lines (without prejudice). Further, since lengths of wire are effectively antennas, they can pick up high frequency interference which a choke will filter out due to the magnetic flux, which differential signals will pass through due to the topology of the choke and its windings.
This video seems to confirm my understanding. Is there any additional nuance that I'm missing?
A transformer can be used as differential probe. Did you ever measure the CMRR of e.g. an Ethernet transformer?
Citation: "All the grounds of the inputs are common"
That is not completely true. It may only be true if you have no ground loops.
Очень в тему! Just in time!
For me, a real test is to solder both inputs together on the board and then measure. Now the output can result from the difference in length and position in the twisted pair of the probe wires. However, it is not worth the effort considering the very high rejection ratio even without that.
Today, Daiyve demonstrates a set up where the probe costs LESS than the oscilloscope!
Just grab that R & S scope for $23,632.
Very nice explanation Dave, enjoyed this one very much.
Kamagatza 🥷
Can you do balanced audio with these?