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cmos designing problem

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maryambk

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hi dear all , i am trying to design below circuit and make it work in saturation region.i tried to do by 0.35u technology and hspice software but i can never make 3 stages work in saturation at the same time.please help me how to do?
circuit is attached.supply voltage must be less than 1volt.
 

Sadegh.j

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I am a little uncomfortable about your supply and the technology. They simply do not go together.

Your circuit seems like a Sooch current source. In these sources, one MOS is ALWAYS in the triode region. Check gray and meyers.

Cheers
 

rajanarender_suram

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dont keep the W/L values of M14,M15 same as M16,M17, since u have Vdd as gate gate voltage of M14 and M15.
 

amarnath

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the circuit you have shown is a folded cascode .I suppose your currents might have been screwed up. Just check if you are pushing enough current in all the stages. Also one way to get vds to distribute equally is to make the pmos size 3.5 times that of an nmos, this is from my experience of designing a folded cascode.Also try to get the overdrives of all transistors to around 100-150mv, this will also boost your gain and also help your operating point .Better post an image with the sizes and also with the region of operation shown in the figure.

amarnath
 

lijianheng

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Try to decrease L/W of M14 & M15, increase L/W of M16 & M17.
 

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