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NIST Technical Note 1337: Characterization of Clocks and Oscillators

NIST Technical Note 1337: Characterization of Clocks and Oscillators

NIST Technical Note 1337: Characterization of Clocks and Oscillators

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_~ ~A _7. PHASE NOISE AND AM NOISE MEASUREMENTS 285• 20 dBmOdBmIIII~IIIIIPHASESHIFTERDELAYLINELOW-NOISEPREAMP. TO AUTOMATICPHASE/AM NOISEMEASUREMENTSYSTEMFIG. 26 A millimeter-wave hybrid phase noise measurement system that produces IFfrequency <strong>and</strong> uses a delay-line discriminator at IF frequency. (From Seal <strong>and</strong> Lance, 1981.)The AM noise measurements are performed according to the following.(1) A known AM modulation (carrier-sideb<strong>and</strong> ratio) must be establishedto calibrate this detector in terms <strong>of</strong> total power output at the IF port.The modulation must be low enough so that the sideb<strong>and</strong>s are at least20dB below the carrier. This is to keep the total added power due to themodulation small enough to cause an insignificant change in the detectorcharacteristics.(2) The rf power levels are adjusted for levels <strong>of</strong> approximately 10 dBmat the reference port <strong>and</strong> 0 dBm at the test port <strong>of</strong> the mixer.IN-236

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