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HMC292ALC3B conversion loss problem

Problems with power transfer are occurring with the HMC292ALC3B. The HMC292 has been mounted on a PCB not identical to the evaluation board using a CPW design and SMA launch which has been tested previously, as shown here:

The setup involves the HMC292 used as a down-converter with an LO of 24GHz at 16dBm, and an IF of 2GHz at -1dBm. The output of the RF port is:

M1 and M2 are the mixed signals, M3 is LO leakage, and the other components are mixing of harmonics of the LO/IF. The above figure is not normalized for cable loss between DUT and FieldFox which is 5.5dB at 24GHz. This is a conversion loss of 30.5dB, and an LO/RF isolation of 55.5dB, which are both inconsistent with the data sheet

Data points at 19, 21, and 25GHz for LO/RF, LO/IF, and RF/IF isolation were measured by exciting the LO port with 13dBm and the RF port with 0dBm while then looking at the other port with a spectrum analyzer (3rd port 50ohm terminated). The results are:

The frequency dependency of the data sheet is not consistent with the measured data points. Furthermore, the return losses were found by measuring the S11 of each port while the other terminals were 50ohm terminated. Cable loss is calibrated out. The following 3 figures are all inconsistent with the data sheet. LO return loss:

The IF return loss:

RF return loss:

HMC292ALC3B was mounted and then was removed and replaced again, so the only thing I can think of is that the heat damaged it. 


Any recommendations would be greatly appreciated!