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Message ID: 205     Entry time: Fri Jul 9 11:45:05 2010
Author: Megan 
Type: Summary 
Category: VCO 
Subject: Phase Noise of Marconis and VCO 

I used the data for the phase noise of the marconis to calculate the individual phase noise of each marconi. The noise of the three are roughly the same. The noise increases with frequency and input range, with the maximum variation in our measurements about 1 order of magnitude. This shows the noise is fairly consistent, but does change with different frequencies used and different input ranges.

We also have some data for the phase noise of the VCO compared with Marconi 2 (with the feedback going to the Marconi). The VCO is currently much noisier than the Marconis, so hopefully we can reduce the noise by modifying the current VCO.

We used swept sine to find the gain of the feedback loop, with a UGF of roughly 2.8 KHz with a gain of 1. With a gain of 100, the UGF is roughly 280 kHz and a peak to peak voltage when unlocked of 438mV.

The gain (for calibration) with the poles and zeroes can be calculated as:


where 4/216 is the resolution of the ADC, pi/Vp-p gives the number of radians per volt, 1000 is the amplification of the signal into the ADC, 0.03 is the first zero (to compensate for the amplifier, which diminishes the signal below 0.03 Hz), and the UGF is the other zero. Multiplication by the zeros ensures the signal above the zeros will not be affected by the transfer function.

As a note - when the signals are calibrated in the DTT, the calibrated data can be saved by exporting the trace, not the signal itself, by exporting win0_pad0_trace1 or whichever trace it is saved under. This removes a need to calibrate the original data outside the DTT.

Attachment 1: IndividualNoise_80MHz_160MHz_10Hz_100HzRanges.png  39 kB  | Hide | Hide all
Attachment 2: Separate_Individual_Noise.png  39 kB  | Hide | Hide all
Attachment 3: VCONoise_Gain1_100.png  25 kB  | Hide | Hide all
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