Mosfet Current Mirror Equation. A basic bjt current mirror circuit courtesy of sedra and smith. To best understand this important circuit building.
To see the e ect of nite on the current mirror we can assume that the two bjt s are matched. 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. 5 the basic mosfet current mirror.
Referring to figure 8 one can see that i ref i c 2i c i c 1 2 2 4 for a pair of matched transisfor i o i c and the current transfer ratio becomes i o i ref i c i ref 1 1 2 2 5.
Current mirror conceptcurrent mirror concept generation of requiredgeneration of required v gs current mirror circuitrycurrent mirror circuitry 1 w 1 w. We will parameter value v t 2 1 v nc ox w l 180 ma v2 v a 50 v. 5 forces the drain current of m1 to equal the input current and the output configuration assures that the output current equals the drain current of m2. The drain current of a mosfet i d is a function of both the gate source voltage and the drain to gate voltage of the mosfet given by i d f v gs v dg a relationship derived from the functionality of the mosfet device.
