Problem with gain boosting

[Usman Hai]

Hi all,
I am designing telescopic opamp with gain boosting with ft=2Ghz. The gain booster are simple levels hift common source and then diff pair. I am having serious stability issues as i am getting pole in right hand plane. I have no idea what caused this and how to overcome this. Can you tell me any tutorial etc when to read the stability issues with gain boosting. I feel its because of 2stage boosters, but I am not sure. Please help me.

 

[bageduke]

RHP pole means you have a negative resistor or capacitor somewhere in your circuit. It may be caused by positive feedback. Have you checked the polarity of your gain booster connection to make sure it is negative feedback?

 

[acbalbason]

hi!

generally gain boosting circuits eat up bandwidth. it's a trade off. increase gain, you lose bandwidth. try putting a compensating capacitor or compensating series RC at the output.

- al

 

[chiguoquan]

maybe your additional amplifier's DC current is smaller than the specification limited by the bandwidth.

 

[xwcwc1234]

Is there any reference papers exist in this forum ?

Added after 40 seconds:

Is there any reference paper in this forum ?

 

[hr_rezaee]

Hi
sketch the schematic.
RHP pole of open loop or close loop?
regards

 

[manissri]

i think gain boosting will not eat ur bandwidht too much .
as u get the bandwith by ur simple folded cascode r telescopic amp but not the gain , to get more gain and bandwidth the bosting circuit is being used.
regard
manish