I need 2-8GHz quadrature modulator with DC IF. I think to use HMC8193 quadrature mixer as modulator (LO input as RFin and RF input as RFout of modulator). Is it possible to apply +10..+20 dBm (or equivalent DC voltage) to IF1 or IF2 input and get constant conversion loss from LO to RF in -30..+10 dBm power range? What approximate IP1dB level (by LO input) and LO-RF conversion loss (equal frequencies at DC IF) should I expect in this case?
We haven't tested this scenario before but the LO needs a constant power level of +18dBm to operate.
Wouldn't constant level of IF input be replacement of constant power level of the LO? We can turn the mixer to required nonlinear mode this way, can't we?
No that wouldn't be the case here as the IF is DC so the diodes/FETs are not switching on and off so no mixing will happen.
Thank you for response.
If I exceed recommended LO power range (14..20 dBm, according to graphs in datasheet), will LO-RF losses be much greater?
Pls see figure 98 in the ds which shows the LO-RF isolation at different LO power levels. Increasing the LO power level will improve the LO-RF isolation at some frequencies.
I have seen, thanks. But if I feed IF pins by DC (0 Hz), wouldn't LO and RF (LO±IF) components be at the same frequency? So will LO-RF isolation be much less than 40-50 dB, like 10-15 dB (that's what I need, actually)?
That might be true however we haven't tested it for this case. The intended use case for this part is as Single Sideband Upconverter or Image Reject Mixer, not as a IQ Modulator nor IQ demodulator. Theoretically the HMC8193 can do this but ADI has other parts optimized for this use case, possibly not for this frequency range which might be the reason to use the part in this use case.
I would recommend ordering an eval board and testing the part in your use case.