I need my arduino to measure the analogue amplitude of a tiny sine waveform that's about 0.01 volts amplitude (but it might range, slowly, to as high as 1 volt). it's about 100 khz if that matters.
My design will use an ADS1220 SPI ADC, so the arduino can dynamically adjust the programmable gain (upto 128x) - but for that to work, I need my input not to go below 0 volts.
Is a synchronous rectifier the right approach? Are there chips/shields which do this, or do I need to find my own transistors and comparator and make one from scratch? Is there a better way?