# Question: 910 for the circuit in fig 918 let i ...

###### Question details

9.10 For the circuit in Fig. 9.18, let I = 1 mA, VCC = 15 V, RC
= 10 k, with α = 1, and let the input

voltages be vB1 = 5 + 0.005 sin 2π × 1000t, volts, and vB2 = 5 −
0.005 sin 2π × 1000t, volts. (a) If

the BJTs are specified to have vBE of 0.7 V at a collector current
of 1 mA, find the voltage at the

emitters. (b) Find gm for each of the two transistors. (c) Find iC
for each of the two transistors. (d)

Find vC for each of the two transistors. (e) Find the voltage
between the two collectors. (f) Find the

gain experienced by the 1000-Hz signal.

Ans. (a) 4.317 V; (b) 20 mA/V; (c) iC1 = 0.5+0.1 sin 2π × 1000t, mA
and iC2 = 0.5 – 0.1 sin 2π ×

1000t, mA; (d) vC1 = 10 – 1 sin 2π × 1000t, V and vC2 = 10 +1 sin
2π × 1000t, V; (e) vC2 – vC1 =

2 sin 2π × 1000t, V; (f) 200 V/V

CAN YOU SHOW THE WORKING?