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generating nA of bias currents?

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amic

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2-nw self biased

I need to generate 30 nA of bias current from I ref available of 10uA, which is difficult based on simple current mirror techniques. Any suggestions???
 

venkateshr

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Hello there ,
For such a requirement widlar mirror is useful . I mean u have a ckt which gives some volts(gate voltage which could be used to replicate further) corresp. to 30 uA for some W/L. .

Use calculated R at the source of the mirrored mosfet and use the available gate voltage .Hopefullly u will get.

Refer WIDLAR current source.
 

GDF

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amic said:
I need to generate 30 nA of bias current from I ref available of 10uA, which is difficult based on simple current mirror techniques. Any suggestions???

That would force you to meet two issues. 1) The ratio of current mirror is
quite large from 10uA to 30nA. 2)The device sizing should be taken care not
going to subthreshold region, so you have to enlarge your channel length.

If I were you, I will make a precise current mirror to mirror 10uA to 500nA.
Then, 500nA to 30nA. The channel legnth you may need it larger than 20um,
even 40um. You can cascode the device if the model doesn't permit you doing that.
 

qslazio

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I think you should cascading your device to produce a large length transistor to increase your transistor's current density to pull it out of subthreshold region.

A normal length diode connected transistor with Id only around several nA will working in triode-like region instead of saturation region. This will result in large gds, and large current variation due to vds variation.
 

hrkhari

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I find this paper meets your requirement:

E.M.C. Galeano, C.G.Montoro, M.C.Schneider," A 2-nW 1.1-V Self Biased Current Reference in CMOS Technology", IEEE Transactions on Circuits and Systems- II:Express Briefs, vol.52, no.2, February 2005, pp. 61-65.

Rgds
 

baniliu

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Could anyone upload that paper above? thank you so much!


Regards
 

Vabzter

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Hi
You can use a Peaking Current Source for generating currents in nA. The design is given in Gray,Hurst,Lewis,Meyer book..Chk it out
BR
Vabzter
 

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