How to determine the phase margin of an opamp in Cadence?

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phase margin cadence

i don't know if there is any direct metho, but you could run an AC analysis & then in the waveform viewer u could use the calculator or set the cursor to the point where the gain becomes )db the corresponding phase subtracted from 180 gives u the PM
 
op amp phase margin

Look stability analysis in Spectre help.
 

phase margin and cadence

Stability Analysis in Spectre is there. Alternatively, you can break the loop (at a high impedance node) and run an AC analysis to view the PM
 

opamp phase

bunda_bindaas said:
Stability Analysis in Spectre is there. Alternatively, you can break the loop (at a high impedance node) and run an AC analysis to view the PM
Click to expand...
 

opamp phase margin

Just run AC analysis and check the Bode Diagram.
 
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phase margin in cadence calculator

Run AC analysis, View waveform of gain and phase then measure phase at 0dB gain this will give you the phase margin. 60º phase margin upto about 180º is considered stable.
 

operational amplifier, phase analysis

in Eldo, there is also .pz analysis. maybe spectre will hace the similiar tool
 

Recently I was also facing the same problem. But I got on my own on how to use 'phaseMargin' function in Cadence ADE Calculator version 5.1, which displays direct result (no need to subtract result again from 180) on ADE Outputs window. May this reply help someone in future.

** These steps are for open loop AC analysis, not stb. Please follow the below steps and let me know if you can't get it.
Note: Assuming you've already run the simulation once.

1. ADE -> Outputs -> Setup

2. Using expression entry: If you've labelled output in schematic as 'Vout', enter the expression as 'phaseMargin(VF("/Vout"))' without single quotes.

3. Using ADE Calculator:
3a. Instead of entering expression, Open Calculator from 'Open' button.
3b. In the calculator window, click on 'vf'
3c. Select output node in schematic.
3d. Return to Calculator window.
3e. Select 'phaseMargin' function under 'Special Functions'. Expression will be displayed.
3f. Go to 'Setting Outputs' window in 'ADE'.
3g. Hit 'Get Expression' button.

4. Add it to the 'Table of Outputs' with name (optional). Hit 'OK'.

with regards,
Praveen
 
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