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kim wan
Joined: 03 Sep 2008
Posts: 4
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 27 Sep 2008 14:13 Fully differential Opamp , OTA for 1V |
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Hello there
I'm looking for papers about 1V fully diff- OTA
I tried, but many of them has bulk diven input
(I can't use bulk driven method)
Can differential Folded cascode amp work?
If u have some good papers or materials, plz help me~
*spec
Vdd 1V
0.18u TSMC
gain : above 50dB
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JoannesPaulus
Joined: 19 Mar 2008
Posts: 58
Helped: 8
Location: POLAND
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| 28 Sep 2008 21:02 Fully differential Opamp , OTA for 1V |
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What's the bw? and the load?
You might have some trouble biasing the cascode transistors but it depends on your desired output swing...
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PaloAlto
Joined: 08 Oct 2007
Posts: 131
Helped: 15
Location: Sevilla, Spain
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| 29 Sep 2008 8:51 Fully differential Opamp , OTA for 1V |
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| I know that Ron Hogervorst and Klass Jan de Langen in the 90s were working on very low voltage amplifiers. I don't know if they went as low as 1V, but if I was you, I would check their work
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kim wan
Joined: 03 Sep 2008
Posts: 4
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| 29 Sep 2008 14:14 Fully differential Opamp , OTA for 1V |
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GBW is no more than 16Mhz.
I'll use this OTA for sigma-delta modulator. so I have capacitive load (max 10pF)
Thank you
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PaloAlto
Joined: 08 Oct 2007
Posts: 131
Helped: 15
Location: Sevilla, Spain
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| 29 Sep 2008 17:37 Fully differential Opamp , OTA for 1V |
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I don't think you are going to get 50dB with a FC structure and badly biased cascodes. Since the BW is small, the solution is to go for 2 stages.
If you still can't get 50dB with 2 stages, you may have to go 3 stages, but that's probably too much for 16MHz and it complicates your stability too much
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JoannesPaulus
Joined: 19 Mar 2008
Posts: 58
Helped: 8
Location: POLAND
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| 29 Sep 2008 18:24 Fully differential Opamp , OTA for 1V |
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| I mostly agree with PaloAlto, but I still think you could be able to do it if your output swing is less then 220mV (single ended). Maybe not over PVT though...
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