(a) If the BJTs of Fig. P4.2 have Is1 5 Is2 5 1.0 fA, VA 5 `, and negligible base currents, fi nd IC1, IC2, and VE. (b) Repeat part (a) if Is1 5 Is2 5 6 fA. (c) Repeat (a) if the BJTs are mismatched...

(a) If the BJTs of Fig. P4.2 have Is1 5 Is2 5 1.0 fA, VA 5 `, and negligible base currents, fi nd IC1, IC2, and VE. (b) Repeat part (a) if Is1 5 Is2 5 6 fA. (c) Repeat (a) if the BJTs are mismatched with Is1 5 4 fA and Is2 5 3 fA. (d) Repeat (a) if the BJTs are perfectly matched but Q1 is 18C warmer than Q2. Hint: use a well-known rule of thumb to ask yourself what voltage VB1 would be needed at Q1’s base to ensure identical collector currents; then, what happens if VB1 is returned to 0 V? (e) Repeat part (a) if the BJTs have VA 5 50 V. (f) Repeat part (e) if Q1’s collector is lifted off ground and tied to a 110-V supply.