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Entry  Mon Oct 7 14:51:20 2019, aaron, Update, Electronics, WFS head RF measurements WFShead_response.pdf
    Reply  Mon Oct 7 19:50:33 2019, gautam, Update, IOO, IMC locking not working after this work IMCflaky.pngIMG_8015.JPG
       Reply  Tue Oct 8 10:29:19 2019, gautam, Update, IOO, MC Transmission scan MC2_transmission_scatter.pdftransmissionMaps.pdfcorrelStructure.pdf
       Reply  Tue Oct 8 16:54:56 2019, rana, Update, IOO, IMC locking not working after this work 
    Reply  Tue Oct 8 16:00:06 2019, aaron, Update, Electronics, WFS head RF measurements WFS_ACresponse.pdfWFS_DCresponse.pdf
       Reply  Wed Oct 9 12:15:05 2019, rana, Update, Electronics, WFS head RF measurements 
Message ID: 14951     Entry time: Tue Oct 8 16:00:06 2019     In reply to: 14945     Reply to this: 14959
Author: aaron 
Type: Update 
Category: Electronics 
Subject: WFS head RF measurements 

I simulated this circuit with zero, but haven't gotten the results to match the measurements above.

Removing the DC readout chain from the circuit does not affect the AC response.
Perhaps something to do with the (currently unmodeled) capacitance of the diode? I think this forms a necessary part of the resonant circuit. The gain is also suspiciously low.
Edit: Indeed, simply adding the 'typical' shunt capacitance (9pF) and a small series resistor (10 Ohm) gives the right qualitative response
The python notebook is in /users/aaron/WFS/electronics.
The DC response flattens off at ~20dB by ~mHz, which also seems longer than the timescales I saw while measuring; I'm not sure I have some of the AD827 parameters correct (eg 'delay')
 
I came across this nice note on photodiodes.
 
 
Attachment 1: WFS_ACresponse.pdf  23 kB  Uploaded Tue Oct 8 19:05:27 2019  | Hide | Hide all
WFS_ACresponse.pdf
Attachment 2: WFS_DCresponse.pdf  20 kB  Uploaded Tue Oct 8 19:05:33 2019  | Hide | Hide all
WFS_DCresponse.pdf
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