what is the influence of gain-peaking in OPAMP

[huangjw]

gain peaking at bode fig

in my simulation of opamp gain and phase margin, the gain beblow 0db, there apear peaking, some case, the peak will over 0db, how the peaking generate, and what will be influence, and is the system safe.
thank you

 

[renwl]

gain peaking at bode fig

the system will be unstable when the peak is larger than 0dB.

 

[RFCMOS]

Re: gain peaking at bode fig

Hi,

Oscillations may happen on your system at the frequency of your peaking.

 

[duet12]

Re: gain peaking at bode fig

Gain peak is possible for OPAMP, epecially happened in multi-stage OPAMP

Let look at a Transfer function s/H(s)=w0*w0+2*a*s+s*s.

the quality factor (Q) is defined as Q=w0/(2*a).

You may remember what butterworth response is. When Q=0.707, the response of this Transfer function is called butterworth response.

When Q>0.707, there will be gain peak.

Therefore, any TF which contains a second-order equation with Q>0.707, there will be a gain peak.

 

[Alan_Nesta]

gain peaking at bode fig

gain-peaking will occur in multi-stage op with cascode (especially in gain-boosting architecture or in architecture has feed-forward path)
be careful to each net's total resistance