Reference no: EM132535105

Problem 1:

Refer to the common emitter amplifier in Figure PI below. Given β = 100, Vcc = 20V, R_B1 = 15kΩ R_B2 = 1 kΩ, R_C1 = 8Ω, R_E1 = 330Ω a You can ignore the early voltage effect.
a) Solve for the operating points, I_CQ, I_EQ, I_BQ, V_c, V_B, V_E and V_CEQ,
b) Suppose the 0 has changed to 200. How do the operating points change?
c) Calculate the overall voltage gain, vo/vin for this amplifier.
d) Calculate the input impedance, Rin,
e) Calculate the output impedance, Rout

Figure P1

Problem 2: Supposed the amplifier in Problem 1 did not achieve enough gain for the application that it was designed for. A second stage of common emitter is added to the original circuit as shown in Figure P2. You can assume that both transistors are in active mode and that they have the same β. If the collector current of Q2 is 1mA, Rc2 = 10kΩ and RE2 = 330 kΩ
a) Calculate the input impedance of the second stage, Rinb2
b) Calculate the overall gain of this cascaded amplifier.
c) Calculate the overall input and output impedances.

Problem 3: For the amplifier in the Figure P3, given β = 100, VA = ∞, Vcc = 48V and 11 = 2.5mA:
a) Draw small signal model for the circuit shown.
b) Calculate the bias conditions, IC, IBQ, IEQ and VCEQ for the circuit
c) Calculate the small signal parameters of the circuit
d) Calculate the overall voltage gain
e) Calculate the input, Ri and output, Ro impedances of this circuit

Problem 4: Consider the following circuit:

Figure P3

Use constant voltage drop model for the diodes with VBE(on) = 0.7V.
a. Determine the state of the diodes and find the value of Vout for Vin = 12V
b. Determine the state of the diodes and find the value of Vout for Vin = -12V
c. Draw the voltage transfer characteristics of the circuit (Vout vs Vin). Clearly indicate the slope of the lines and the transition points.
d. Assume Vin = 5Vcos(10t). Draw the output voltage, Vout with respect to time.

Problem 5: Given a uniformly doped semiconductor having acceptor doping of 10¹⁵cm^-3:

(a) Calculate the electron concentration, hole concentration and resistivity of the sample if T = 450 °K, Eg =1.02 eV, μa = 400 cm²/Vs and lap = 150 cm²Ns

(b) Calculate the velocity of the electrons and holes if the applied electric field is 10⁴ V/cm.