Draw the circuit symbol for a NPN BJT. Label the terminals and currents. Chose the reference directions that agree with the true current directions for operation in the amplifier region.

4. A Darlington transistor is essentially an array of two transistors connected as shown below. Assume both transistors follow our simple model with a current gain of B=100. Determine the maximum value of R2 that will just saturate the transistors, and pass full current through the load resistance R1. v2 V2 R2 PULSE (0 5 0) Q2 NPN R1 10 Q1 NPN V1 24

Q3 Figure 3 shows two current mirrors based on MOSFET. Derive a formula relating the input current Iin to the output current Iout for the current mirror on the left of Figure 3 stating any assumption. (a) (b) Derive the input resistance Rin and output resistance Rout for the circuit on the left of Figure 3. State any assumption. (c) Derive a formula relating lin and Iout for the circuit on the right of Figure 3 assuming that M1 and M2 are identical, and that the length and width of the channel for the transistor M4 are double respect to those of M3. State anv assumption. VDD M3 M4 out Iout M1 M2 M1 M2 Vss = 0 V Vss = 0 V Figure 3