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How to determine the input value for 1st-order low pass OTA-C filter?? (Read 832 times)
Jlim
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How to determine the input value for 1st-order low pass OTA-C filter??
Feb 23rd, 2013, 7:08pm
 
hello,

How to determine the input value for ibias and Vin to generate the correct AC response???urgent!!!
Hope someone can help me~~~
Thanks Smiley
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buddypoor
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Re: How to determine the input value for 1st-order low pass OTA-C filter??
Reply #1 - Feb 24th, 2013, 2:48am
 
Jlim, I don`t understand your question.
The circuit was designed by YOU, right?
In this case, only you know about the chosen bias points and the necessary bias input voltages.
Or do you expect that we are simulating your circuit?
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LvW (buddypoor: In memory of the great late Buddy Rich)
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Jlim
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Re: How to determine the input value for 1st-order low pass OTA-C filter??
Reply #2 - Feb 24th, 2013, 9:24pm
 
Because i have try a lot of value for Ibias and Vin input~~but i still cnt get the correct general AC response for low pass filter~~ Sad Sad
Can someone help me try to simulate this circuit and what value i should put??? Smiley
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Horror Vacui
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Re: How to determine the input value for 1st-order low pass OTA-C filter??
Reply #3 - Feb 25th, 2013, 6:36am
 
If you don't get a meaningful AC response, then probably your operation point is incorrect. Check voltages and currents in the devices! Check that all transistors are in saturation!
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Lex
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Re: How to determine the input value for 1st-order low pass OTA-C filter??
Reply #4 - Feb 25th, 2013, 8:27am
 
Your ibias is not flowing into a current mirror... so the gate of NM3 and NM2 is floating.
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