Question We are using the AD8364 in the band 2.110 to 2.155GHz. We are getting a relatively large frequency dependent power measurement error. For example, if the device is calibrated (intercept and slope) at 2132.5MHz andwe inject a signal at 2112.5MHz and 2152.5MHz the indicated power level variesby +0.38dB/-0.37dB at 2112.5 and 2152MHz from the nominal value at 2132.5MHz. Feedback: It looks like the AD8364 does indeed have significant output voltage variation vs frequency. The attached plot shows how the output would vary vsfrequency if each device was calibrated at a single frequency. For AD8364 (light blue), you can see that it falls off sharply above 2 GHz. HMC1030(another dual rms responding detector), has a much flatter response in this region.You balun seems to have an insertion loss that is increasing slightly vs frequency. This is making things slightly worse. if you could find a balunwhich has insertion loss that was decreasing in this freq range, that might improve things a little. @EOF& Answer