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If we want precisely matched PMOS and NMOS current source, for example, they are both equal to 100uA, which kind of circuit can match them well? thanks.
If you need it very precisely, have the currents run through equal resistors between source and VDD of the pmos current mirror PFETs, and use a high gain amplifier to control the gate of the 2nd PMOS.
"Match them well" probably means different things to
different people, applications, etc. Cascading the
PMOS mirror (say) from one branch of the NMOS
mirror-rack can get you to maybe 1%-range with
a cascode mirror and sensible L. Is that good enough?
Could be for a "housekeeping" differential amp, but
maybe not for a >7 bit DAC.
The more elaborate you get in trying to slave one
to the other, or both to a primary reference, the more
mismatch terms you pick up - do you come out ahead
in the end, or is simple nearly as good (or better)?
The answer you get from a corners type simulation,
and what you get from MC+MM, may be different.
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