Folded cascode OPAMP with CLASS-AB o/p Stage

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rampat

Joined: 27 Jun 2007
Posts: 83
Helped: 1
Location: bangalore

21 Aug 2007 7:02 Folded cascode OPAMP with CLASS-AB o/p Stage

Has anyone wrked on the following architecture ? Cud u please tell the design approach for this..And also how to take care of THD in this design..

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ambreesh

Joined: 21 Feb 2005
Posts: 369
Helped: 21

27 Aug 2007 15:41 Re: Folded cascode OPAMP with CLASS-AB o/p Stage

Have not designed something like this.
But trick would be get the floating current source right wayLast string is the ouput stage as we all can see, The once before it are for biasing of the floating current source in the output of folded cascode.

Alan_Nesta

Joined: 11 Aug 2005
Posts: 103
Helped: 5

29 Aug 2007 7:09 Folded cascode OPAMP with CLASS-AB o/p Stage

This is a classAB OP with floating-current mirror.
You can get help from JSSC Dec. 1994 Hogervorst's paper.

songjunjian

Joined: 02 Aug 2007
Posts: 26
Helped: 3

29 Aug 2007 7:25 Re: Folded cascode OPAMP with CLASS-AB o/p Stage

you can increase the openloop gain of the opa, which can increase the thd, please take care of the impedence of float current source, the impedence will increase as the frequence increase. you can add a capacitor between the float current source.