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

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 further

Kind Regards.

DC Gain =>

80 = 20 log | DCGain |

So DC Gain = 10^4 = 10000

Is this correct?

rude man
Homework Helper
Gold Member
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?

donpacino
Gold Member