23 Jan 2019 28:30 1
7 1

For nerds only!
This is the 23rd in a series of videos about sideband noise in oscillators, frequency multipliers, the components we use to build them as well as the tools used to measure sideband noise.
Here level 29 Schottky diode mixers are used to evaluate sideband noise. Termination at the difference frequency (DC) should be 150 ohms while termination at the sum frequency (20 MHz) should be 18 ohms. At about 45 kHz offset the noise is at about -188 dBc/Hz. This is the sum of phase noise and AM noise of the two oscillators and the Schottky mixers. It seems (very uncertain) that the sideband noise from the Schottky mixers dominates.

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