Mosfet Current Mirror Equation. δ v t h v t h 2 v t h 1 displaystyle scriptstyle delta v th v th2 v th1. A basic bjt current mirror circuit courtesy of sedra and smith.
To see the e ect of nite on the current mirror we can assume that the two bjt s are matched. The implementation of the current mirror circuit may seem simple but there is a lot going on. T1 l ref v rr i if the load resistor becomes larger than t1 ref rv i the voltage ds2 v will drop below the excess gate voltage gs t22 v v and thus the second mosfet will enter the triode region.
I out w l 2 w l 1 i in consider fig.
The implementation of the current mirror circuit may seem simple but there is a lot going on. The simple two transistor implementation of the current mirror is based on the fundamental relationship that two equal size transistors at the same temperature with the same v gs for a mos or v be for a bjt have the same drain or collector current. To best understand this important circuit building. T1 l ref v rr i if the load resistor becomes larger than t1 ref rv i the voltage ds2 v will drop below the excess gate voltage gs t22 v v and thus the second mosfet will enter the triode region.
