my design depend on measuring, sensing and controlling the small current about (mA) my design builded by op amps, so must be the small current (mA) is converted to voltage.
how small current about (0.5 mA) measured and transformed into (microAmp)
to used for op amps..... or directly from (mA) to voltage for op amps....
Siply feed the truangular waveform to one input of the comparator and the sinewave to the other. Just like you would do with DC, except now the triangle replaces it.