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= DC PD calculations for OMC = = DC PD for OMC =
== OMC DC PD amplifier analysis ==
The full package for the analysis of OMC DCPD amplifier ([[https://dcc.ligo.org/LIGO-D060572|LIGO-D060572]]) with various transimpedance (Made by Koji Arai)
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- https://dcc.ligo.org/LIGO-D060572

Koji's model:
- https://www.dropbox.com/s/un7hvo59w43o9d9/OMC_DCPD_amp_model.zip?dl=0		  * [[attachment:OMC_DCPD_amp_model.zip]]
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 * transimpedance.pdf: This is a basic check to see how the input current is converted to the output. At DC, the transimpedance gain is rT*2 because of the differential output. Between 100-10K, the gain is boosted to rT*(11^2).
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- transimpedance.pdf: This is a basic check to see how the input current is converted to the output. At DC, the transimpedance gain is rT*2 because of the differential output. Between 100-10K, the gain is boosted to rT*(11^2).  * input_current_noise.pdf: The input noise is 20pA/rtHz (= the shot noise of iDC~1mA) when rT is 100Ohm. When rT is smaller than r8 (100Ohm), r8 cause the dominant thermal noise. When rT is larger, it dominates the noise. However, above rT=1kOhm, the input current noise of the 1st opamp dominates the noise. That's why the improvement of the input referred noise for rT=1k, 3k is suppressed.
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- input_current_noise.pdf: The input noise is 20pA/rtHz (= the shot noise of iDC~1mA) when rT is 100Ohm. When rT is smaller than r8 (100Ohm), r8 cause the dominant thermal noise. When rT is larger, it dominates the noise. However, above rT=1kOhm, the input current noise of the 1st opamp dominates the noise. That's why the improvement of the input referred noise for rT=1k, 3k is suppressed.

- input_range.pdf: This indicates the input current amplitude which makes the circuit saturated when a sinusoidal wave at the amplitude and frequency. For example, 120mA at DC makes the circuit saturated. This is because the first (and second) stage opamp only has the ±12V output range in LISO. This limit is hit when 120mA is given to the transimpedance resistance of 1K.		  * input_range.pdf: This indicates the input current amplitude which makes the circuit saturated when a sinusoidal wave at the amplitude and frequency. For example, 120mA at DC makes the circuit saturated. This is because the first (and second) stage opamp only has the ±12V output range in LISO. This limit is hit when 120mA is given to the transimpedance resistance of 1K.
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 * In the LISO model, LT1028 was used instead of LT1128. However, this is not a problem in our application.
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- In the LISO model, LT1028 was used instead of LT1128. However, this is not a problem in our application.

- The output of the circuit is to be differential. This requires a proper noise estimation, strictly to say. i.e., the noises from the output stage are uncorrelated; however, the noise from the previous stages are coherently added. To deal with this issue, I have added a low noise buffer+differential amp using ideal opamps (op00) to the output stage. So notice that this is not a part of the real circuit.		  * The output of the circuit is to be differential. This requires a proper noise estimation, strictly to say. i.e., the noises from the output stage are uncorrelated; however, the noise from the previous stages are coherently added. To deal with this issue, I have added a low noise buffer+differential amp using ideal opamps (op00) to the output stage. So notice that this is not a part of the real circuit.
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 * The primary model is "D060572.fil" .
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- The primary model is "D060572.fil" .  * The liso directory contains "fil" which is a Mac version of LISO. Replace this with an appropriate version if you are not on Mac.
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- The liso directory contains "fil" which is a Mac version of LISO. Replace this with an appropriate version if you are not on Mac.  * Use a Perl script "mfil" to run different model runs in a batch.
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- Use a Perl script "mfil" to run different model runs in a batch.  * mfil produces "runAa" files. "A" ranges from 1 (rt=10Ohm) to 6 (rt=3000Ohm).
  . "a" ranges from 1 to 3. 1 is the transimpedance gain calculation. 2 is the input noise analysis. 3 is the max range calculation.
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- mfil produces "runAa" files. "A" ranges from 1 (rt=10Ohm) to 6 (rt=3000Ohm).
  "a" ranges from 1 to 3. 1 is the transimpedance gain calculation. 2 is the input noise analysis. 3 is the max range calculation.

- A Matlab script "D060572.m" summarizes the results. It uses my class file "freq_data_tools.m" , which needs to be placed in the path. 		  * A Matlab script "D060572.m" summarizes the results. It uses my class file "freq_data_tools.m" , which needs to be placed in the path.

DC PD for OMC

OMC DC PD amplifier analysis

The full package for the analysis of OMC DCPD amplifier (LIGO-D060572) with various transimpedance (Made by Koji Arai)

Method

The circuit model in LISO was made. The transimpedance resistor (rT) was varied from 10 Ohm to 3000 Ohm with a half-decade log-spacing (i.e., 10, 30, 100, ...). The transfer function (total transimpedance gain) in Ohm (=V/A), the input-referred current noise in A/rtHz, and the max input current range to have no saturation, in A, were calculated in each case.

How to interpret the plots

  • transimpedance.pdf: This is a basic check to see how the input current is converted to the output. At DC, the transimpedance gain is rT*2 because of the differential output. Between 100-10K, the gain is boosted to rT*(11^2).
  • input_current_noise.pdf: The input noise is 20pA/rtHz (= the shot noise of iDC~1mA) when rT is 100Ohm. When rT is smaller than r8 (100Ohm), r8 cause the dominant thermal noise. When rT is larger, it dominates the noise. However, above rT=1kOhm, the input current noise of the 1st opamp dominates the noise. That's why the improvement of the input referred noise for rT=1k, 3k is suppressed.
  • input_range.pdf: This indicates the input current amplitude which makes the circuit saturated when a sinusoidal wave at the amplitude and frequency. For example, 120mA at DC makes the circuit saturated. This is because the first (and second) stage opamp only has the ±12V output range in LISO. This limit is hit when 120mA is given to the transimpedance resistance of 1K.

Notes on the model

  • In the LISO model, LT1028 was used instead of LT1128. However, this is not a problem in our application.
  • The output of the circuit is to be differential. This requires a proper noise estimation, strictly to say. i.e., the noises from the output stage are uncorrelated; however, the noise from the previous stages are coherently added. To deal with this issue, I have added a low noise buffer+differential amp using ideal opamps (op00) to the output stage. So notice that this is not a part of the real circuit.

How to run the LISO model

  • The primary model is "D060572.fil" .
  • The liso directory contains "fil" which is a Mac version of LISO. Replace this with an appropriate version if you are not on Mac.
  • Use a Perl script "mfil" to run different model runs in a batch.
  • mfil produces "runAa" files. "A" ranges from 1 (rt=10Ohm) to 6 (rt=3000Ohm).
    • "a" ranges from 1 to 3. 1 is the transimpedance gain calculation. 2 is the input noise analysis. 3 is the max range calculation.
  • A Matlab script "D060572.m" summarizes the results. It uses my class file "freq_data_tools.m" , which needs to be placed in the path.

KAGRA/Subgroups/IOO/OMC/DCPDCalculation (last edited 2018-10-13 00:57:57 by YutaMichimura)