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Do we use wilson current mirror in CMOS?

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pugongying

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wilson current mirror

In bipolar,we use wilson current mirror to get rid of the systematic error due to base current
but in CMOS,we don't have "gate current",then do we use wilson current mirror in CMOS?
if so, what's the benefit of using it?
Thanks in advance
 

wilson current mirror cmos

It can be used to set constant vds for each mirror transistor, but very seldom. Normally people would use wide swing technique to achieve higher swing.
 

wilson current mirror output impedance

wenadinho said:
It can be used to set constant vds for each mirror transistor, but very seldom. Normally people would use wide swing technique to achieve higher swing.
Click to expand...

why current mirror need wide swing and large output impedance?
 

cmos current mirror stable current

evilguy said:
why current mirror need wide swing and large output impedance?
Click to expand...
Idea current source has infinite current compliance and infinite output resistance.
 

description of wilson current source

isaacnewton said:
evilguy said:
why current mirror need wide swing and large output impedance?
Click to expand...
Idea current source has infinite current compliance and infinite output resistance.
Click to expand...

yes i know the ideal output impedance for current mirror is infinite. in term of performance, is current mirror tend to mirror stable current if the the output impedance is large?
 

advantage wilson mirror cmos

why current mirror need wide swing and large output impedance?
Click to expand...

A current mirror has wide swing means that itself consume less head room while providing correct mirroring current (transistor still in saturation).
This is of cause desirable, as you reserve larger headroom for other purpose. A simple example would be a NMOS differential pair and a NMOS current mirror. If this NMOS current mirror consume less headroom (Vds), basically it give more input linear range to the differential pair.

Large output impedance is always desirable when u dealing with current. This high impedance provide large DC current gain that ensure mirroring error is minimized.
 

current mirror

The Wilson current utilize the negative feedback to increase the output impendance
and stable the output current .
 

wilson current mirror cmos

@sengyee88

thank you very much for telling me. have a nice day.
 

current mirror large output resistance desirable

I am still confused whether the wilson current source has an advantage over the basic cascode current mirror (not the high swing cascode)?

PS,just for example,in the textbook of Gray's 4th edition,what is the advantage of Fig4.15(page277,Improved MOS wilson current source) over Fig4.9(page267,Cascode current mirror using MOS)?
 

output resistance cmos wilson current mirror

Idea current source has infinite voltage cross the current source and infinite output resistance.
 

Re: current mirror

fanrong said:
The Wilson current utilize the negative feedback to increase the output impendance
and stable the output current .
Click to expand...

Sometimes, we do need Wilson current to make a negative feedback loop to make a constant offset voltage.
 

If you are using very large mirror FETs and very low currents,
the gate node can present a significant pole. Attaching the
source of the Wilson buffer FET brings down that node
impedance dramatically. However this is not always what you
want; it can also worsen high frequency PSRR.
 

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