UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Science R. W. Brodersen, Homework #8 EECS140 S. Emami, and D. Sobel (Due 12/10/04) Fall 2004 1. Consider the circuit shown in Figure 1.. L1L2VinIout Figure 1 For the transistor above, consider only it’s gm and CGS. (i.e. roàinfinity, 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 LVinCLRLRindVout Figure 2 a) At an operating frequency of ωo, 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, ωo, Qind, and RL. Note that the inductor has a finite Q (=Qind), so that the relationship between Rind and L is: indindQLR⋅=ω b) Calculate the expression for the gain at ω=ωo 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 ω0 = 2π*5GHz=31.41 Grad/s QIND = 10 (@ 5GHz) d) Verify the gain calculations from part (b) in spice with the parameters from part
View Full Document