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Message ID: 2372     Entry time: Mon Jul 22 20:21:33 2019
Author: Shalika 
Type: Noise Budget 
Category: 2micronLasers 
Subject: Noise Analysis of Circuit using SR785 Spectrum Analyzer and Zero Simulation 

The transimpedance amps, differential circuit and the whitening filter for the 2um Extended InGaAs detectors were made and their noise level was evaluated. The examination of noise was done without the diodes. For every analysis, SR785 spectrum analyzer was used and a simulation using zero in python was also done. The SR785 was controlled using the python program to get the data. The input was AC coupled and Hanning window function was used during the task of getting data.

**The noise of SR785 spectrum analyzer is also mentioned, which was measured by deploying a terminator at one channel. The noise labelled as SR785noise mentions the spectrum analyzer noise alone.

**The noise of the components, with SR785 mentioned along with them, indicates the noise observed using the Spectrum analyzer.

Attachment 1: The circuit diagram

The usual transimpedance configuration was made using the OP27 IC. There are two TIA as we will be using two PD in our final circuit. The two TIA are connected to Whitening Filter respectively. The Whitening filter has a gain of 10. Apart from that, the output of the two TIA is connected to a differential circuit and whose output is in turn connected to another independent whitening filter.

Attachment 2: The amplifier noise Part I

The noise of TIA1 was analyzed using the SR785 spectrum analyzer and also by simulating the circuit using zero in python. 

Attachment 3: The amplifier noise Part II

The noise of TIA2 was analyzed using the SR785 spectrum analyzer and also by simulating the circuit using zero in python. It was observed to be exactly similar to that observed of TIA1.

Attachment 4: The differential circuit noise levels

The noise level of the differential circuit was measured by shorting both the input terminals and observing the output at the pin6 of IC.

Attachment 5: The Whitening Filter noise level.

The noise of the Whitening filter was measured by grounding the input terminal (pin 3) at taking the measurement at the output. The gain of the filter is 10. 

Attachment 6: The TIA and Whitening Filter, connected together, noise level.

The TIA and Whitening filter were connected in series and the noise was observed at the output of the whitening filter.

Attachment 7: The Simulation of Circuit in Zero

The complete circuit was configured using zero. It will help us analyze the noise that we are not expecting. Please open it using Jupyter Notebook.

Attachment 1: full_circuit.pdf  251 kB  Uploaded Mon Jul 22 21:50:11 2019  | Hide | Hide all
Attachment 2: Noise_at_node_naout.pdf  29 kB  Uploaded Mon Jul 22 21:57:59 2019  | Hide | Hide all
Attachment 3: Noise_at_node_nbout.pdf  29 kB  Uploaded Mon Jul 22 21:58:10 2019  | Hide | Hide all
Attachment 4: Noise_at_node_ndout.pdf  29 kB  Uploaded Mon Jul 22 21:58:41 2019  | Hide | Hide all
Attachment 5: Noise_at_node_nout.pdf  29 kB  Uploaded Mon Jul 22 21:59:05 2019  | Hide | Hide all
Attachment 6: Noise_at_node_nw1out.pdf  30 kB  Uploaded Mon Jul 22 21:59:17 2019  | Hide | Hide all
Attachment 7: noise_simulation.zip  1 kB  Uploaded Mon Jul 22 22:11:48 2019
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