Question

Consider the circuit shown in Figure 1. A Q-point value for IC between a minimum of 4 mA and a maximum of 5 mA is required. Assume that resistor values are constant and that β ranges from 100 to 300. It is desired for RB to have the largest possible value while meeting the other constraints.

(a) Determine the values of RB and RE.

(b) Explain the contribution of resistor RE for thermal stabilisation of this circuit (Thermal stabilisation - Variation to Q-point due to temperature is minimum. β is highly temperature dependent and increases with increasing temperature )

(c) The circuit shown in Figure 1 has to be modified to use as a common emitter amplifier to amplify a signal vin = 1 sin(6283t + 30◦ ) mV. Suggest a suitable circuit showing input and output connections of the signal circuit. Show the value of the capacitors you have selected.

+15 V BEQ

Answer 1

+15V ik to 300 3 109 RB SV KE I+B 1チE 1+B LOOP 1Oo

o4m

RE 4'3-0-2-1014-85.2 tonat Ic= 5mA /p-300 Ic 300 IE = 5.0167 mA Lco iA RE43 0 0835 o 8405 Ko RE o 3405 KL 50167 m