Analog Discovery 2 || Network Analyzer

[RajatDas]

I am using Digilent Analog Discovery 2. Want to use it as Network Analyzer S21 (gain/phase) mode. Kindly guide me.  Also in the GUI I am not able to find any option for changing Receiver bandwidth.

Till now I have connected wavegen 1 and channel 1 to my input circuit and channel 2 to the output of the circuit. 

I am attaching one figure, I required similar kind of options in Analog Discovry Kit2. Please help.

[JColvin]

Hi @RajatDas,

What software are you using? I do not recognize it, though I'm guessing this is not being used with the Analog Discovery 2 based on what you have described.

It is not possible to change the bandwidth of the analog inputs on the Analog Discovery 2. As per the Analog Discovery 2 specifications, https://digilent.com/reference/test-and-measurement/analog-discovery-2/specifications#analog_inputs, the bandwidth is either 9 MHz at -3 dB while using the provided MTE cables, or 30 MHz when using the BNC Adapter.

Regarding your question about if the Analog Discovery 2 is able to calculate the S21 forward gain, I do not believe this is possible to do on the Analog Discovery 2, partially because there is no direct feedback loop in hardware to view the isolated transmitted Wavegen signal (a1) and not simply the reflected signal (b1).

Calculating the S parameters might be possible to do on something like the Analog Discovery Pro 3450 which does have this direct digital loopback, but it is not implemented in the WaveForms software.

I will defer to Attila (creator of the WaveForms software) if he thinks such a feature is feasible within WaveForms for Digilent hardware.

Thanks,
JColvin

[RajatDas]

Thank you @JColvin for your answer. The software is from other tools, not from analog discovery 2. I want to implement similar setup by using Analog discovery. 

[RajatDas]

Thank you for answering my query. Just want few more clarification. Please guide me. I want to measure the response of the device under test in Network Analyzer mode. For that I have used webgen C1 to the input of the device under test and also connect the webgen C1 to the Oscilloscope Channel 1. Then the output of the device under test I have connected to the Oscilloscope Channel 2. Now I want to observe the response of the device under test. To minimize the noise I want to decrease the Oscilloscope Channel 2 (receiver) bandwidth.

[JColvin]

Hi @RajatDas,

Unfortunately, it is not possible to decrease the inherent bandwidth of analog inputs of the Analog Discovery 2 to prevent the capture of higher order frequency components or additional noise. Aside from ensuring that the two devices share a common ground (as I expect you do not want to add onto your DUT with an external low pass filter), there is not much else you would be able to do to minimize extraneous noise.

Thanks,
JColvin

[RajatDas]

Thank you @JColvin.

[attila]

Hi @RajatDas

Actually the Network and Impedance Analyzers performs some filtering at lower frequencies since the averaged samples are used to minimize the effects of eventual aliases, higher frequency noise/harmonics.
The average/averaging options can be used to improve the accuracy of the measurements.

[RajatDas]

ok. Thank you @attila. I will try.