How can I remove a large common mode signal from the differential input of ad8137 while maintaining the high gain-bandwidth prroduct? In my particular case the common mode signal is +-12V at 20-50 kHz. Thanks for any advise, Tom
So look at the AD8417 or AD8418A.
You have to give us more.
What supply voltages are available?
What gain for the AD8137?
Application? (current sensing in a switching regulator??)
Look at the AD8130 also.
Thanks for the reply. I kept my initial question general with the hope that the answer would also be useful to other members. Here's a mock-up of the sort of current sensing application I'm interested in (sorry for the pictures, I couldn't find where to upload a file, so I could directly provide the spice model):
As you can see, the LC oscillator (two different inductor sizes are shown) creates a large common-mode voltage on Vad+ (and Vad-) after it is isolated by the two mosfets.
however, the differential voltage over the sense resistor is, of course, small.
The frequency of the signal in my example is only for illustration purpose and can be up to 1MHz, while the gain in the ad8137 is in the order of 10-100 (50 in the example). The application is for ambient temperature, so I don't see any problem there. If possible, I'd like to stick with a single-rail supply (12V and 5V), but if absolute necessary dual-rail is possible. The question is, what is the best way to remove the common-mode signal.
I have looked at the ad8130, but it has the same, and very limited, common-mode voltage range.
Thanks in advance to anyone who can help,
Thanks, they could do the job. Are there any speedier alternatives as well?
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