Understanding Schottky Frequency Response/Flatness

Nov 18, 2005 2 Replies
T

New to Schottky diode detectors for measuring rf signal levels. I am trying to understand typical response (dB) Vs Frequency (Ghz) plots. In order to generate a frequency response graph is the following necessary:



1- input desired power level at CW freq to diode (say for example

-10dBm, 5Ghz)



2- measure output (for example -0.8VDC)
3- change to next freq (6Ghz)
4-set input power (dBm) until output is -0.8Vdc. (Say for example

-10.25dBm)



Is the flatness (freq response) now 0.25dB?



Thanks for any response



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M

yes, the complication comes in becasue the diode response may not be linear so a 1 dB change of the RF input may not produce a 1 dB of the DC output.

The way you have defrined the test at a fixed DC level, solves that problem.

Mark

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T

Mark, On typical diode flatness plots shown on manuf spec, the output voltage or power of the diode is not shown. The plots are typically dB vs Freq. Should the output voltage or power be indicated? Or is it common to assume that the sensitivity of the diode is constant? THanks G

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