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Entry  Thu Aug 1 11:25:27 2019, Shalika Singh, DailyProgress, 2micronLasers, Noise Analysis of Circuit using SR785 Spectrum Analyser and Zero Simulation Circuit.pdffull_circuit.pdfSR785_display_screen.pdfNoise_across_TIA.pdf
    Reply  Thu Aug 1 13:01:15 2019, rana, DailyProgress, 2micronLasers, Noise Analysis of Circuit using SR785 Spectrum Analyser and Zero Simulation 
Message ID: 2381     Entry time: Thu Aug 1 11:25:27 2019     Reply to this: 2382
Author: Shalika Singh 
Type: DailyProgress 
Category: 2micronLasers 
Subject: Noise Analysis of Circuit using SR785 Spectrum Analyser and Zero Simulation 

Input Referred noise to be calculated for trans-impedance.

Attachment 1: The Setup,

The setup was made on a breadboard, as per the circuit diagram.

Attachment 2: The Circuit Diagram on paper,

>>  the TIA with a gain of 5.1k

Attachment 3: Noise across TIA on SR785 screen

This is the noise as seen on the screen of the SR785

Attachment 4: Noise across TIA captured using the SR785 template file

The input-referred current noise across the TIA was measured using SR785 and was compared against the graph obtained from ZERO simulation.

 

** There is a difficulty in capturing the exact form of data as displayed on the SR785. Previously, I had captured the full span by keeping the start frequency as 1Hz. This gave only two points between 1Hz and 100Hz, all the rest of 798 points out of 800 were plotted at a higher frequency. This gave a straight line of higher magnitudes at low frequency(1Hz to 100Hz) since there were only 2 points. But the plot on the SR785 screen looks different.

** This time, I divided the measurements into 3 parts, 1Hz to 100 Hz, 100Hz to 10kHz and 10kHz to 100kHz. This left me with a graph which looks clumsier than the previous ones. I guess if there is a way that the template files of SR785 can be modified then it can give a graph which will align properly to the simulated results. For the time being, I can try again to take measurements in 3 sections but this time with fewer(300 instead of 800) points.

** It's difficult to avoid 60Hz harmonics with a circuit kept in open as this one. Lots of its effects are visible in the plot.

 

Attachment 1: Circuit.pdf  3.892 MB  Uploaded Thu Aug 1 12:40:28 2019  | Hide | Hide all
Circuit.pdf
Attachment 2: full_circuit.pdf  251 kB  Uploaded Thu Aug 1 12:41:05 2019  | Hide | Hide all
full_circuit.pdf
Attachment 3: SR785_display_screen.pdf  3.671 MB  Uploaded Thu Aug 1 12:41:54 2019  | Hide | Hide all
SR785_display_screen.pdf
Attachment 4: Noise_across_TIA.pdf  43 kB  Uploaded Thu Aug 1 12:42:11 2019  | Hide | Hide all
Noise_across_TIA.pdf
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