EECE 310 Homework 1, Fall 2011

American University of Beirut Department of Electrical and Computer Engineering EECE 310 – Electronics Fall 2011 – 2012 Homework 1 Due Wednesday October 5, 2011 at 9:00 am Problem 1. [50 points] An amplifier has the transfer characteristic: vO = 12 – 10 (vI – 3)2 V. where vO and vI are in volts. This transfer characteristic applies for 3 < vI < vO + 3 V, and vO positive. At the limits of this region, the amplifier saturates. a) [15 points] Sketch and clearly label the transfer characteristic. What are the saturation levels L+ and L– and the corresponding values of vI? b) [10 points] Bias the amplifier to obtain a DC output voltage of 6 V. What value of input DC voltage VI is required? c) [10 points] Calculate the value of the voltage gain (in V/V and in dB) at the bias point. d) [15 points] If a sinusoidal input signal is superimposed on the DC bias voltage VI, that is: , find the resulting vO. Express vO as the sum of a DC component, a signal component at  with amplitude A1 and another component at 2with amplitude A2. The component at 2is undesirable and is the result of the nonlinear transfer characteristic of the amplifier. If it is required to limit the ratio to 1%, what is the corresponding upper limit on Vi? Problem 2. [50 points] An amplifier operating from +/– 12.7 V power supplies has a linear transfer characteristic except for output saturation at +/– 11 V. a) [12 points] The peak-to-peak value of the largest sinusoidal wave that can be applied at the amplifier input without output distortion is 0.5 V. Find the amplifier voltage gain in V/V and in dB. b) [8 points] What is the corresponding output power for an 32  load? c) [20 points] What is the power gain, in W/W and in dB, if the input power is 10 mW? What is the current gain of the amplifier, in A/A and in dB? d) [10 points] What is the amplifier efficiency (in %) if the DC current drawn from each power supply is 200 mA?