Simscape current source at higher frequency

Hello!

I am trying to simulate modulated light incident on a photodetector. I am modeling the photodetector's output electrically using a current source. I am having a lot of trouble getting the current source to work at the current and frequency levels I would like (90uA dc offset, 72uA ac amplitude, ~40kHz). When I use the Scope to look at the current, I just see a flat line @ 40kHz. When I run the current source at 10Hz I see a beautiful sine wave. Does the Scope not sample quick enough to be able to plot a 40kHz signal?

This is my first time using Simscape to build anything so I don't know if I'm making a newbie mistake.

Any advice is appreciated. Thank you!

Answer 1

[Manoj Mirge]

The “solver configuration” block in the model has the sample time as 0.001 sec. So, the “scope” block will observe the value of current at the interval of 0.001 seconds I.e., the frequency of the “scope” block is 1000 Hz. The “scope” block will be accurate if the frequency of “scope” block is more than frequency of “current source” block.

To get the accurate results for the 40 KHz frequncy of current source kindly set the frequency of “scope” block more than 40 KHz. This can be done by setting the “Sample time” block parameter of the “solver configuration” block as lower than 0.000025 seconds.

Hope this helps.