analogbjtcurrent-mirroridealtransistors
Is the ideal output impedance of a Wilson Current Mirror 0?
Also, in the formula for the actual output impedance of Wilson Current Formula (i.e. R_out = [B/2]* r_o), what does r_o stand for? Also, what is the order of magnitude of a Wilson Current Mirror?
I would use bipolars, not FETs. The FETs have to be particularly well matched for this to work, which is difficult to guarantee with discrete parts. Use two NPNs. With enough emitter resistance, you should be able to to better than 5%. Keep in mind you can't use 5% resistors if you want accuracy better than 5%. Try something like this:
If that doesn't do what you need, a opamp circuit should do it, but will be a bit more complex.
You will never get the ac and dc performance with the Wilson current mirror that the Howland current source can attain. Plus the Howland can sink and source current.
For the Wilson current pump, consider the mirroring BJT's constant current region - there is a voltage on the base set by the "other" BJT (that is acting like a diode) and you know that this sets a current into the base of both transistors - look how compliant the graph is - outside the saturation region. It's not really a good constant current source when Vce changes: -
The Howland current pump (on the other hand will have a compliance graph that is as flat as a pancake meaning you can swish Vce around and the collector current will remain really quite flat (dependent on resistor matching of course).
Best Answer
The mirror like an ideal current source has infinite impedance except for the leakage r_o due to the Early Effect and Beta, B
https://en.wikibooks.org/wiki/Circuit_Idea/How_the_Wilson_current_mirror_equalizes_the_currents
Order of magnitude for current depends on the device Imax, Pmax and gain matching