How to compare power measured when the input impedance of the ADL5902 is no longer 50 ohms?

Hi there,

Higher input termination impedance generally provides higher RF voltage at the input, and consequently improved detector sensitivity and output voltage. But higher input termination impedance also creates more sensitivity to stray shunt capacitance. Also, keep in mind that printed RF transmission lines at the higher impedance can sometimes be more difficult to realize and also contribute to the frequency flatness problem. 

If necessary, it may be possible to use very small series inductor at the detector input to help "peak up" the high frequency response. This peaking inductor would be placed after the resistive termination, but before the detector RF input. The DC blocking capacitor is still necessary. Beyond the peaked-up frequency, response degrades faster than had the peaking inductor not be present. 

Hi there,

Higher input termination impedance generally provides higher RF voltage at the input, and consequently improved detector sensitivity and output voltage. But higher input termination impedance also creates more sensitivity to stray shunt capacitance. Also, keep in mind that printed RF transmission lines at the higher impedance can sometimes be more difficult to realize and also contribute to the frequency flatness problem. 

If necessary, it may be possible to use very small series inductor at the detector input to help "peak up" the high frequency response. This peaking inductor would be placed after the resistive termination, but before the detector RF input. The DC blocking capacitor is still necessary. Beyond the peaked-up frequency, response degrades faster than had the peaking inductor not be present.