Hello!
I hope I put this in the right forum category. Since I am asking about demodulation and common techniques in RF applications I figured this would be the place to ask.
I want to measure an unknown impedance using an I/Q demodulator.
Setup:
I was thinking of using a DDS (Direct Digital Synthesizer) as the sine wave signal generator. Splitting this signal to a reference signal and an excitation signal. The reference signal will go directly to the LO input while the excitation signal will go through a "black box" with an unknown impedance (RC, no L), and then to the RF input. The signal out from the "black box" will probably be attenuated and phase shifted. I am interested in getting the phase shift phi = arctan(Q/I) and amplitude A = sqrt(I^2 + Q^2).
The AD8333 has this block diagram: