> *I want my waveform to oscillate from 10uA to 10mA* That's a peak-to-peak value of 9.99 mA or, a peak value of 4.995 mA. So, use two current sources in parallel; one set to produce a peak current of 4.995 mA and the other set to deliver the offset current 5.005 mA DC. Current sources in parallel add and you'll get what you require.