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Entry  Thu Sep 5 11:10:08 2019, Shalika Singh, Noise Budget, TIA, Noise Analysis of transimpedance amplifier 7x
    Reply  Thu Sep 5 15:40:22 2019, rana, Noise Budget, PD noise, Noise Analysis of transimpedance amplifier 
Message ID: 2416     Entry time: Thu Sep 5 11:10:08 2019     Reply to this: 2417
Author: Shalika Singh 
Type: Noise Budget 
Category: TIA 
Subject: Noise Analysis of transimpedance amplifier 

Noise analysis was done using SR785. SR560 was used with a flat gain of 100 to get above the noise floor of SR785. The input range was constantly maintained at -44dBVpk for all measurements. Voltage regulators LM317 and LM337 were used to power the circuit. 200 averages were taken for all the measurements. The TIA was configured with a 5.1k feedback resistor and 100pf feedback capacitor. Please refer elog:2390 for better understanding of the circuit diagram. 

** Referring to elog:2411 the 8kHz noise bump went away on its own without changing anything in the circuit. I have no clue how it happened and why it's not happening again. 

Attachment 1: Noise analysis using OP27 in transimpedance amplifier. At Frequencies below 100Hz, data was taken in 4 parts, starting from 0Hz with a span of 25Hz but with 10 number of averages(fewer averages were taken only in this case).  At high frequencies(above 100Hz) data was taken with 200 averages. A noise was observed to be 10pA/rtHz was observed at 10Hz and 3pA/rtHz above 300Hz.

Attachment 2: LT1792 was used in this case. It was seen that it is less noisy as compared to OP27. The noise was observed to be 2pA/rtHz above 20Hz.

Attachment 3: LT1012 was used for this measurement. The noise was observed to be 3pA/rtHz above 20Hz.

Attachment 4: AD820 was used for this case. The noise was observed to be 3pA/rtHz above 500Hz.

Attachment 5: OPA140 was used for the TIA during this measurement. The noise was observed to be 2pA/rtHz above 2Hz.

Attachment 6: Noise comparison between all the OpAmps used. It was seen that OP27 isn't able to deliver performance as expected because it is getting affected a lot by the noise(1/f noise). OPA140 performs better than all the others. 

Attachment 7: Zip file to re-create all data

Attachment 1: Noise_across_TIA_Op27.pdf  79 kB  Uploaded Thu Sep 5 12:14:44 2019  | Hide | Hide all
Attachment 2: Noise_across_TIA_LT1792.pdf  72 kB  Uploaded Thu Sep 5 12:33:04 2019  | Hide | Hide all
Attachment 3: Noise_across_TIA_LT1012.pdf  72 kB  Uploaded Thu Sep 5 12:33:13 2019  | Hide | Hide all
Attachment 4: Noise_across_TIA_AD820.pdf  73 kB  Uploaded Thu Sep 5 12:33:23 2019  | Hide | Hide all
Attachment 5: Noise_across_TIA_OPA140.pdf  74 kB  Uploaded Thu Sep 5 13:37:53 2019  | Hide | Hide all
Attachment 6: Noise_comparison_across_TIA.pdf  262 kB  Uploaded Thu Sep 5 13:40:01 2019  | Hide | Hide all
Attachment 7: TIA_4sep.zip  343 kB  Uploaded Thu Sep 5 13:44:23 2019
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