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Design >> Analog Design >> how does this circuit works? help!
https://designers-guide.org/forum/YaBB.pl?num=1278313275

Message started by xwj623 on Jul 5^th, 2010, 12:01am

Title: how does this circuit works? help!
Post by xwj623 on Jul 5^th, 2010, 12:01am

this circuit confused me for a long time.
how does it works? And can someone tell me some reference papers or key words?
thanks.

Title: Re: how does this circuit works? help!
Post by xwj623 on Jul 6^th, 2010, 7:56pm

Is there nobody know this circuit? :(

Title: Re: how does this circuit works? help!
Post by raja.cedt on Jul 6^th, 2010, 10:00pm

hi,
in the circuit node names are not visible so don't know proper connectivity, so could you please post with neat schematic. By the way from where you got this ckt?
Thanks,
Rajasekhar.

Title: Re: how does this circuit works? help!
Post by carlgrace on Jul 9^th, 2010, 1:46pm

The circuit is an amplifier. The circuit on the left is a simple OTA. Then the output current of the OTA is mirrored into the PMOS device MP2. The mirrored current is then dumped into two resistors to generate the output voltage. These resistors also generate a common-mode output voltage which is used for the common-mode feedback.

The gain is related to the gm of the input device, the two current mirror gains and the value of the output resistor.

Carl

Title: Re: how does this circuit works? help!
Post by AnalogDE on Jul 9^th, 2010, 4:26pm

What's the function of the branch with MP3? I don't get that part.

Title: Re: how does this circuit works? help!
Post by xwj623 on Jul 11^th, 2010, 6:23pm

Then what's the role of MP3 & MN5?
It seems that the MP3 and MN5 construct a postive feedback, is there
a stability issue?
Then how the CMFB works?
What the GBW depends on when at a cap loading?

carlgrace wrote on Jul 9^th, 2010, 1:46pm:

Title: Re: how does this circuit works? help!
Post by XY-oriented on Jul 12^th, 2010, 7:46am

my 2 cents ...the second part of the circuit looks like a 1st generation current conveyor.... though not a conventional one! ;)

Title: Re: how does this circuit works? help!
Post by xwj623 on Jul 12^th, 2010, 6:37pm

yes, i have ever think about it as a CCI,
but the CMFB circuit seems strange for a CCI.

XY-oriented wrote on Jul 12^th, 2010, 7:46am:

my 2 cents ...the second part of the circuit looks like a 1st generation current conveyor.... though not a conventional one! ;)