EXERCISES 8.12 For the circuit in Fig. 8. 19, let 1-1 m1A, Vcc-15 VR-|0 kQ, with α 1, and let the input voltages be: t'ai = 5 + 0.005 sin 2π × 1000t. volts, and = 5-0.005 sin 2π × 10001, volts. (a) If the BJTs are specified to have gr of 0.7 V at a collector current of 1 mA. find the voltage at the emitters. (b) Find g, 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) ic0.5+0.1 sin 2T x 1000t, mA and i-0.5-0.1 sin 2.t x 1000t mA; (d) toi-10-l sin 2π x 1000t. V and ia-10 + l sin 2mx 1000t. V: (e):'a-va-2 sin 2zx 1000t, V: (f) 200 V/V 8.3 The BJT Differential Pair Cc 2 Wid 2 Rc 2i 02 Vid 2 Figure 8.19 The currents and voltages in the differential amplifier when a small differential input signal Wa is applied The Collector Currents When vig Is Applied For the circuit of Fig. 8.19, we may use Eqs. (8.73) and (8.74) to write α! (8.75) EXERCISES 8.12 For the circuit in Fig. 8. 19, let 1-1 m1A, Vcc-15 VR-|0 kQ, with α 1, and let the input voltages be: t'ai = 5 + 0.005 sin 2π × 1000t. volts, and = 5-0.005 sin 2π × 10001, volts. (a) If the BJTs are specified to have gr of 0.7 V at a collector current of 1 mA. find the voltage at the emitters. (b) Find g, 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) ic0.5+0.1 sin 2T x 1000t, mA and i-0.5-0.1 sin 2.t x 1000t mA; (d) toi-10-l sin 2π x 1000t. V and ia-10 + l sin 2mx 1000t. V: (e):'a-va-2 sin 2zx 1000t, V: (f) 200 V/V 8.3 The BJT Differential Pair Cc 2 Wid 2 Rc 2i 02 Vid 2 Figure 8.19 The currents and voltages in the differential amplifier when a small differential input signal Wa is applied The Collector Currents When vig Is Applied For the circuit of Fig. 8.19, we may use Eqs. (8.73) and (8.74) to write α! (8.75)