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Message ID: 1748     Entry time: Wed Jul 15 12:11:17 2009
Author: Stephanie 
Type: Update 
Category: General 
Subject: Multiply Resonant EOM Update 

This week I've been working on testing the first version of the prototype circuit. Initially, I tested the circuit that I built last week, which had resistors in the place of the transformer. The magnitude and phase of the transfer function, as measured by the Agilent 4395A, are shown in the attached plot (first plot, MeasuredTransferFunction_R.jpg). The transfer function doesn't look like the simulated transfer function (second plot, BuiltCkt_ExpectedResponse.png), but I think I see the three peaks at least (although they're at the wrong frequencies). I spent some time trying to recreate the actual transfer function using LTSpice, and I think it's reasonable that the unexpected response could be created by extra inductance, resistance, capacitance and interaction between components.

When the transformer arrived  yesterday, I replaced the resistors in the circuit with the transformer, and I have measured the following response (last plot, MeasuredTransferFunction.jpg). The gain is much lower than for the circuit with the resistors; however, I am still trying to track down loose connections, since the measured transfer function seems very sensitive to jiggled wires and connections.

Meanwhile, the parts for a flying-component prototype circuit have been ordered, and when they arrive, I'll build that to see if it works a little better.

Attachment 1: MeasuredTransferFunction_R.jpg  48 kB  | Hide | Hide all
Attachment 2: BuiltCkt_ExpectedResponse.png  39 kB  | Hide | Hide all
Attachment 3: MeasuredTransferFunction.jpg  54 kB  | Hide | Hide all
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