Extracting information from a Bode Plot (PM, GM, etc...)

Click For Summary

Discussion Overview

The discussion revolves around extracting information from a Bode plot related to a unity feedback system. Participants seek to identify key parameters such as DC Gain, Bandwidth, Gain Bandwidth Product (GBW), unity frequency, Phase Margin, and Gain Margin. The context includes theoretical understanding and practical application in electrical engineering.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant requests guidance on extracting various parameters from the Bode plot, indicating a lack of resources on stability and feedback.
  • Another participant calculates the DC Gain using the formula 80 = 20 log | DCGain |, concluding that DC Gain = 10^4 = 10000, and later confirms this calculation.
  • A third participant states that the loop gain for a unity feedback system is the same as the open-loop gain of the amplifier and mentions that bandwidth typically refers to the 3dB-Bandwidth.
  • There is a suggestion that stability margins can be derived using appropriate definitions, questioning whether all definitions are known to the participants.

Areas of Agreement / Disagreement

Participants generally agree on the calculation of DC Gain, but the discussion remains unresolved regarding the extraction of other parameters and the definitions needed for stability margins.

Contextual Notes

Participants express uncertainty about definitions and the application of concepts related to stability and feedback, indicating potential gaps in knowledge or resources.

Waxterzz
Messages
82
Reaction score
0
Hi all,

1. Homework Statement
http://imgur.com/kqZK1Vv

This is the loop gain (A.F.) of unity feedback system.

I need to extract

DC Gain
Bandwidth
GBW (is GBW Gain Bandwith ?)
f unity (I suppose this is unity frequency)
Phase Margin
Gain Margin

What is the optimal PM and f2/GBW for time and frequency domain applications?

Homework Equations


Don't know => this is not really homework as such, plus in the books I got about electrical engineering not much is said about stability and feedback...

The Attempt at a Solution



U guys don't need to solve this for me,

What I want is instructions how I can solve it, since I truly have no material about this topic, then I shall try and present it, and you guys can help me furtherKind Regards.
 
Physics news on Phys.org
DC Gain =>

80 = 20 log | DCGain |

So DC Gain = 10^4 = 10000

Is this correct?
 
Waxterzz said:
DC Gain =>

80 = 20 log | DCGain |

So DC Gain = 10^4 = 10000

Is this correct?
Yes.
Next: bandwidth?
 
Loop gain for a unity feedback system is identical to the open-loop gain of the amplifier.
Hence, you have nothing to do than to apply the definitions of the various data you are interested in.
Normally, the "bandwidth" is identical to the 3dB-Bandwidth.
Stability margins can easily derived by using the appropriate definitions.

Do you know all the definitions?
 

Similar threads

Bode plot and stability margins
  • · Replies 5 ·
Replies
5
Views
3K
Controller Design with Bode Plots
  • · Replies 3 ·
Replies
3
Views
4K
Gain bandwidth product from bode plot
  • · Replies 4 ·
Replies
4
Views
10K
What is the Frequency for Unity Loop Gain in Low-Pass Amplifier with Feedback?
  • · Replies 4 ·
Replies
4
Views
2K
Engineering Creating a Bode Plot for a Series RC High Pass Filter
  • · Replies 8 ·
Replies
8
Views
4K
Bode plots and crossover frequency
  • · Replies 4 ·
Replies
4
Views
8K
How Do You Construct Bode Plots for Cascaded CR Networks?
  • · Replies 1 ·
Replies
1
Views
2K
How Do You Determine Gain and Parameters from a Bode Plot?
  • · Replies 1 ·
Replies
1
Views
12K
Bode Plots: Plotting Homework Statement
  • · Replies 1 ·
Replies
1
Views
5K
Engineering Circuits: Bode Plot for Frequency vs. Voltage Gain | Homework Help Statement
  • · Replies 1 ·
Replies
1
Views
6K