Exercise In a certain application, a signal source having 60 kl of source impedance, Rs, produces a 1 V,ms signal. This signal must be amplified to 2.5 V,rms and drive a 1 kN load. Assuming that the phase of the load voltage is of no concern, design an operational amplifier circuit for the application. Hint: Choose, arbitrarily, input resistor, R1 = 100kN and find feedback resistor, Rf. Since phase is of no concern and the required voltage gain is greater than 1, we can use either an inverting or noninverting amplifier. Answers: Rf (inverting) = 400 k2, Rf (noninverting) = 150 k2 %3D

Figure 2 shows a typical BJT amplifier, with its parasitic capacitances displayed. The current gain of the transistor is B=150 and the voltage gain of the amplifier is Am =-125. The small signal resistances of the transistor are re =16 ohm and r0 = infinity, respectively. The values of resistors and capacitors in the figure are: R1 =80 kohm, R2 =20 Kohm, Rc = 2 Kohm, RE = 2 Kohm, Rs =50 W, RI=5 kohm, Cs=2 uF, Cc=2 uF, Ce =10 uF, Cbc =4 pF, Cbe = 10 pF, Cce =1 pF, Cwi = 4 pF, CWO = 9 pF, and Vcc = 20 V. a) Sketch a simplified circuit diagram of Figure 2 for high frequency analysis. b) Using the concept of "Miller effect capacitance", calculate the input and Output Miller effect capacitances of Figure 2, respectively. C) Determine the upper cut-off frequency of Figure 2 that is imposed by its input network only. d) Explain briefly the possible ways to increase the upper cut-off frequencv of this amplifier.