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pra
Joined: 08 Jan 2005
Posts: 83
Helped: 5
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 08 Jan 2005 4:20 OTA design |
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Hi,
I am new to this group.
I am designing a telescopic cascode compensation opamp with N-Mos as i/p transistors.
I am doing the design in SPICE.
I am getting problem with the CMFB circuit.
How can I do simulation of CMFB circuit using SPICE?
Is there any material for the designing procedure!!
If so please mail it to me
Thanks In Advance
Pra
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Sergiu_Q
Joined: 14 Jan 2003
Posts: 259
Helped: 6
Location: Romania
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| 08 Jan 2005 6:27 Re: OTA design |
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you will find a lot of examples in only 2 books 
"analog cmos design " allen & holberg
"analog circuit design " Chung Yu Wu
on edaboard forum you can find a lot ok books about analogic ic design
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pra
Joined: 08 Jan 2005
Posts: 83
Helped: 5
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| 09 Jan 2005 4:09 Re: OTA design |
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Thanks
while simulating it in the spice, some of the transistors are going in to linear region.
Is there any commands in spice to varry the bias voltages for making all transistors in the saturation region!!!
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bzaki
Joined: 27 Dec 2004
Posts: 44
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| 09 Jan 2005 11:10 OTA design |
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Hello,
I designed a similar OTA from about a year using spice also. It was fully differential so I needed also a CMFB. It worked me well. When I connected the whole circuit the CMFB worked and it adjusted the dc level of the output nodes as excatly I calculated it.
I think there is no such command in spice. Only sweep the dc bias until u get all transistors in saturation.
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brightblade
Joined: 11 Jan 2005
Posts: 17
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| 11 Jan 2005 23:17 OTA design |
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| i recommend you the book called Design of Analog CMOS circuits by Behzad Razavi. You can find all about analog CMOS IC design there. Fınd it and you will have no problems about OTA and opamps
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borodenkov
Joined: 02 Mar 2004
Posts: 129
Helped: 11
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| 12 Jan 2005 1:41 Re: OTA design |
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| pra wrote: |
| Is there any commands in spice to varry the bias voltages for making all transistors in the saturation region!!! |
SPICE is nothing more than a similation program (i.e. differential equations solver). Do not expect black magic from it It is only YOU who make the design, not your EDA tools...
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nickooeda
Joined: 15 Sep 2004
Posts: 44
Helped: 2
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| 13 Jan 2005 6:08 OTA design |
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| OTA is very simple, u should caulculate all params in hand not with EDA tools!! It is very useful for your future work!! good luck
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layes2
Joined: 03 Dec 2004
Posts: 346
Helped: 5
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| 14 Jan 2005 10:19 Re: OTA design |
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just add a cmfb circuit
continouse or use phase1 and phase 2
to simulate it
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