Is it OK to PWM a current source?
Assuming you do not want to modify your current source, and only want to modify the load: Instead of inserting the switch in series, it is more important to provide an alternate path for the current to take.  If I understand you correctly, you are considering the schematic on the left.  Replacing it with the one on the right should work better. Your control signal will be inverted; when the signal is high, the load will be shorted so not drawing current.







simulate this circuit &ndash; Schematic created using CircuitLab