Is it relevant to use the quadrature demodulator ADL5380 evaluation board in a Doppler radar project in terms of frequency? When LO and RF inputs are beneath 20kHz different, I and Q outputs are not sinusoidal anymore. It seems there is a filter that filter low frquencies.
Thank you in advance.
Without knowing the specifics of your application, my comment is that you may be limited by the phase noise of the LO/RF source you are using.
In addition to that, you might find the attached circuit note useful. In that application the RF and LO are at the same frequency and hence the output is at DC.