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Entry  Tue Apr 26 22:02:00 2011, tara, Notes, FSS, measurement for OLG TF of the TTFSS TF1.png
    Reply  Wed Apr 27 21:07:44 2011, tara, Notes, FSS, measurement for OLG TF of the TTFSS TTFSSOLG.png
Message ID: 594     Entry time: Wed Apr 27 21:07:44 2011     In reply to: 592
Author: tara 
Type: Notes 
Category: FSS 
Subject: measurement for OLG TF of the TTFSS 

 I reoptimized the gain of the TTFSS, and measured the OLG of the TTFSS loop. The UGF is 150 kHz.

 

  To optimize the gain, I observed the noise from MIXER OUT while adjusting the gains. As the gain increases, the noise at MIXER OUT will be suppressed. I didn't see any oscillation even though the gain was set to maximum, but oscillation occurs once I injected the excitation, so I reduced fast gain. Phase margin might not be enough. I also used 10dBm attenuator on the LO input instead of 12dBm to get 10dBm input.

The gain setting are

FAST: 980

COMMON 1000

I measured the TF, as described here. The result is plotted below. The UGF is @150 kHz. It is lower than we thought.

TTFSSOLG.png

 

 

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