EE 541 University of Southern California Viterbi School of Engineering Choma Solutions, Homework #01 5Fall Semester, 2011 UUUniversity of SSSouthern CCCalifornia USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering EE 541: Solutions, Homework #01 Fall, 2011 Due: 08/31/2011 Choma Solutions−Problem #01: The model shown within the symbolic network “box” in Figure (P1) is a small signal, and therefore linear, equivalent circuit of an emitter-degenerated, common emitter amplifier. The amplifier is driven by a voltage source whose Thévenin resistance is Rs, and its load termination consists of a resistance, Rlin shunt with a capacitance, Cl. In this problem, Rs= 50 , Rl= 1.2 K, Re= 120 , and Cl= 300 fF. The transistor model parameters are rb= 120 , r= 3.3 K, ro= 18 K, and = 220 amps/amp. IVsRsRerbrClRlIroI2V2I1V1RoutRinFigure (P1) (a).Derive analytical expressions for each of the four h-parameters of the degenerated common emitter amplifier. In the network box delineated in Figure (P1), the input port current, I1, is identical to the branch current, I, whence the controlled current satisfies I ≡I1. The hybrid h-parameters, h11and h21, are each evaluated under the condition of a short circuited output port; that is, under the condition of V2= 0. With V2= 0, o21e120rIβIRII,(P1-1) which leads immediately to 2oe2211oeV =0βrRIh218.54 amps/amp .IrR(P1-2) Note that h21is very close to parameter because ro>> Re. Continuing with V2= 0, 1bπ1e12VrrIRII,(P1-3) and using (P1-2) to eliminate current I2in this KVL relationship,
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