Differential input and Analog Discovery 2 - Network Analyzer

[thoriam]

Hi guys

I need to test my amplifier with Network Analyzer in Wavefoms. But my amplifier has differential inputs and third ground pin. How can I test it using Analog Discovery 2?

[attila]

Hi @thoriam

In case you are supplying the amplifier with +/- voltages you can connect one of the inputs to GND.
In case you are supplying it with + and GND, you can drive one input with a DC voltage using Wavegen Channel 2.
The Network Analyzer controls Wavegen Channel 1 to generate stimulus signal and you can specify offset.

[thoriam]

I have + and - to drive and also GND so I need to short - and GND right? My device is for EMG (electromyography).

[attila]

Hi @thoriam

There are different types of opamps which can be used in multiple ways.
Could you provide more detail about the amplifier and setup/eval board?

[thoriam]

Im using LT1167 in typical muscle sensor from application note on my own board.

[attila]

Hi @thoriam

There are multiple use-cases of such instrumentation amplifiers.
In case you are referring to the REF input, this can be connected to GND or to other potential, between -V+1.6 and +V-1.6
https://www.analog.com/media/en/technical-documentation/data-sheets/1167fc.pdf

I'm not an EE but such development looks like:
1. use the specifications and characteristics from the datasheet to design your circuit
2. simulate
3. use scope and/or network analyzer to verify

[thoriam]

Thats what I want to do: use scope and verify. I have a board I just want to test it now. I powered my amplifier with -3V and 3V. I also have two inputs (+ and -) and REF pin connected to GND.

So basically I have 3 pins - GND(REF), + and -. What is the best way to verify my design which i already design, simulate and manufacured?