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| ice:servo-opls [2016/07/22 17:57] – [Understanding the Transfer Function] Michael Radunsky | ice:servo-opls [2016/07/22 18:07] – [Calculating Phase Noise] Michael Radunsky |
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| =====Understanding the Transfer Function===== | =====Understanding the Transfer Function===== |
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| <imgcaption xfer_func center|Schematic of the OPLS right-side panel, showing the configurable transfer function and its user-controls.>{{ :ice:opls-loopfilter-xfer-function.jpg?nolink&700 |}}</imgcaption> | <imgcaption xferfunc|Schematic of the OPLS right-side panel, showing the configurable transfer function and its user-controls.>{{ :ice:opls-loopfilter-xfer-function.jpg?nolink&700 |}}</imgcaption> |
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| The charge pump in the OPLS outputs a signal proportional to the phase-error and the transfer function is as shown in <imgref xfer_func >. However, the OPLS will typically be used to control a //frequency//-tunable device (such as a laser). In this configuration, the effective loop filter is not the one shown in <imgref opls_side_panel>, but includes a extra integration corresponding to converting the phase-error input to a frequency error. Thus, ω<sub>I </sub>sets the frequency transition from single-integration to double-integration and ω<sub>I </sub> from single-integration to proportional feedback. It is important to understand this 'hidden' integrator when configuring the loop filter parameters. | The charge pump in the OPLS outputs a signal proportional to the phase-error and the transfer function is as shown in <imgref xferfunc>. However, the OPLS will typically be used to control a //frequency//-tunable device (such as a laser). In this configuration, the effective loop filter is not the one shown in <imgref opls_side_panel>, but includes a extra integration corresponding to converting the phase-error input to a frequency error. Thus, ω<sub>I </sub>sets the frequency transition from single-integration to double-integration and ω<sub>I </sub> from single-integration to proportional feedback. It is important to understand this 'hidden' integrator when configuring the loop filter parameters. |
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| =====Calculating Phase Noise ===== | =====Calculating Phase Noise ===== |
| <WRAP center round box 450px><html><center></html> **D2-135 Phase-Noise Floor = -213 + 20Log(N) + 10Log(F<sub>REF</sub>)**<html></center></html></WRAP> | <WRAP center round box 450px><html><center></html> **D2-135 Phase-Noise Floor = -213 + 20Log(N) + 10Log(F<sub>REF</sub>)**<html></center></html></WRAP> |
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| where N is the value of the divider and F<sub>REF</sub> is the reference frequency as measured in Hz. For more details, please see [[http://www.vescent.com/2012/calculating-phase-noise-from-the-d2-135/|http://www.vescent.com/2012/calculating-phase-noise-from-the-d2-135/]] . | where N is the value of the divider and F<sub>REF</sub> is the reference frequency as measured in Hz. For more details, please see this [[http://www.vescent.com/2012/calculating-phase-noise-from-the-d2-135/|application note]]. |
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