Hello,

I'm trying to get some feedback on a differential op-amp circuit concept I've come up with. The concept is to capture a time varying magnetic field. Using faraday's law, a voltage is induced on a loop. Electrostatic noise is also picked up on the loop and is negated via differential amplifier.

I'm am using a fully differential op amp to impedance match a Z=100 ohm twisted pair line (CAT6A cable)

This is part one of my design. Later I will need to match the balanced Z=100ohm to a 50 ohm line so that I can read my signals on an oscilloscope.

I am using 100pF capacitors on the Vs +/- of the op-amp to smooth the signal I've read this is a good practice. I've seen people use two capacitors to do this so I might need to add one more.

Any feedback is greatly appreciated.

 

I don't think you'll get much. It looks like all of your loops are grounded.

 

What is the frequency of the desired signal?
Expected signal amplitude from the coil?
What are the cable lengths involved?

 

I don't think you'll get much. It looks like all of your loops are grounded.

I see the problem there. Thank you. How about this?

 

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What is the frequency of the desired signal?
Expected signal amplitude from the coil?
What are the cable lengths involved?

The frequency of the signal will be as high as 60MHz. Possible up to 200MHz.

The expected amplitude will be on the order of .1 - .01 Volts.

The cable length will be a 2.1meters CAT6A cable that will be connected to a feed through coupler. Then the second cable coming from that coupler will be about 1.6 meters. I wanted to use a balan or some kind of impedance matching device to go from CAT6A to coax BNC to connect to the oscilloscope.