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 and we inject a signal at 2112.5MHz and 2152.5MHz the indicated power level varies by +0.38dB/-0.37dB at 2112.5 and 2152MHz from the nominal value at 2132.5MHz.
Given that the bandwidth is only 45MHz I'm surprised how quickly the errors build as frequency is varied. The errors are independent of power level, giving me some confidence in our single frequency calibration (performed at 2132.5MHz). We are using a 4:1 balun (Anaren Part No BD1722J50200AHF)with 10pF 0402 feed thru caps.
I have attached a screen shot of part of our circuit implementation - is there anything we could alter to improve the error as frequency is varied?