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xwj623 Community Member Offline Posts: 36	how does this circuit works? help! Jul 05^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.
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xwj623 Community Member Offline Posts: 36	Re: how does this circuit works? �help! Reply #1 - Jul 6^th, 2010, 7:56pm Is there nobody know this circuit?
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: how does this circuit works? �help! Reply #2 - 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.
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carlgrace

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Posts: 231
Berkeley, CA

Re: how does this circuit works? �help!
Reply #3 - 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

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AnalogDE Senior Member Offline Posts: 137	Re: how does this circuit works? �help! Reply #4 - Jul 9^th, 2010, 4:26pm What's the function of the branch with MP3? I don't get that part.
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xwj623

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Posts: 36

Re: how does this circuit works? �help!
Reply #5 - 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:

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

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XY-oriented Junior Member Offline Posts: 23	Re: how does this circuit works? �help! Reply #6 - 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! ;)
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xwj623 Community Member Offline Posts: 36	Re: how does this circuit works? �help! Reply #7 - 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! �;)
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