UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Science R W Brodersen S Emami and D Sobel Homework 8 Due 12 10 04 1 Consider the circuit shown in Figure 1 EECS140 Fall 2004 Iout L1 Vin L2 Figure 1 For the transistor above consider only it s gm and CGS i e ro infinity CGD 0 etc a Determine the size of L1 and L2 such that the input impedance is purely real and exactly 50ohms at an operating frequency of 5GHz gm 10mS CGS 80fF b Calculate the GM of this circuit for the parameters given and L1 L2 as determined from part a 2 Consider the circuit in figure 2 Rind CL RL L Vout Vin Figure 2 a At an operating frequency of o we seek to use an inductor to cancel out the capacitance at the output CL Determine the size of the inductor L that is required in terms of CL o Qind and RL Note that the inductor has a finite Q Qind so that the relationship between Rind and L is Rind L Qind b Calculate the expression for the gain at o of the circuit with and without the inductor present c Re do parts a and b for the following device parameters gm 10mS RL 1kohm CL 1pF 0 2 5GHz 31 41 Grad s QIND 10 5GHz d Verify the gain calculations from part b in spice with the parameters from part c
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