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What's the function of Resistor in Current Mirror Circuit

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enchanter

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What's the function of R(isistor) in the current mirror circuit?
thanks.

83_1283855330.png
 

It's not just a current mirror circuit, it's a voltage respectively current reference utilizing current mirrors. M2 has an area multiplied by K.
 

this configuration is also called Widlar current source, you can search "Widlar current source" in Wiki.
and this is also a voltage independent current reference in which you need to add the start-up circuit to make it work right.
the resistor is added due to this equation Vgs=sqrt(2IdsL/unCoxW)+Vth, the wider the transistor, the smaller the Vgs, so you need the transistor to make up the voltage drop.
 

Hi,

Where can I find this entire paper? It will be highly appreciate if you can send me either the link or as an attachment. Thank you!

The original circuit is from Eric Vittoz' paper "Analog Circuits in Weak Inversion", s. the PDF below:
View attachment 49083
 

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