As I continue with my design of CCS to be used on my next designs as part of the supply filtering stage, I looked at testing the performance of my latest CCS using the following circuit:
The limitations I have currently is that my waveform generator can do 7Vrms maximum and in low frequency the existing noise level will be the limitation clearly. As suggested by Gary Pimm, adding a battery operated differential preamp at the point of test will be a great way of raising the low level signal from the sound card interface noise floor. That, will be for a future day. I just want to see how well the CCS performs.
I set the CCS to 30mA and measured attenuation from 50Hz to 30kHz. The results are quite encouraging despite the lack of pre-amplification:
The real life CCS is not that great as in the simulation. There is about 10dB difference with the Spice simulation. You can see that I can measure below -130dB attenuation without a pre-amplifier. Still is quite good, more than what we need for.
The CCS is operating to the level of what I need, so test passed 🙂
