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vivkr

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Re: pole zero doublet
Reply #15 - Mar 20^th, 2009, 12:40am

zzhang wrote on Mar 19^th, 2009, 11:52pm:

i have design a gainboost amp, the main amp is telescopic and the aux amp is foled. the pole-zeros are all real number when the three amps simulated seperately. but when i simulted the gainboost one, the first two doublets which were arised by two aux ampa are complex numbers. I doubt how the complex numbers doublts arise,why they weren't the real numbers doublts.

What else do you expect? The auxiliary amps after all are now in closed-loop.

Vivek

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Sarig Junior Member Offline Posts: 31	Re: pole zero doublet Reply #16 - Mar 20^th, 2009, 5:20am Simple answer: when you start playing with tricks to fix your PM by adding zeros or compensation Ideas then problmes start and if yo usee that your phase is not acting like 1st / 2nd order but aslo rise sometimes then you got some doublet issue. Erez
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Manas

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Bangalore,INDIA

Re: pole zero doublet
Reply #17 - Feb 18^th, 2010, 11:08pm

raja.cedt wrote on Mar 3^rd, 2009, 10:23pm:

hi,
� �i think it �is always better to check doublet effect in time response,because in ac simulation u may miss doublet if they are very close and if step is large of course with transient response also same will happen if we are not �care....

How you will see the doublet effect from the time response ??

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Berti

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Posts: 356

Re: pole zero doublet
Reply #18 - Feb 18^th, 2010, 11:33pm

Manas, you will find the answer to your question in the following paper:

@article{KamathJSSCDec74,
B.Yeshwant Robert G.Meyer and Paul R. Gray
Relationship Between Frequency Response and Settling Time of Operational Amplifiers
IEEE of Solid--State Circuits
1974
volume = "sc-9",
number = "6",
month = "December",
pages = "347-352"
}

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