# A hand calculations approximate a capacitor as a

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a) Hand calculations: Approximate a capacitor as a transmission line of length L and Width W. First, constrain W so that the line is less than a half-wavelength in the dielectic (rd/0). What is the maximum length if the line input impedance is not to go to infinity at 300 GHz ? What is the low-frequency capacitance of this line ? b) simuations: make ADS plots of Z11 and Y11 vs frequency.
3 c) Hand calculations: Approximate a capacitor as a sector of a circle of flare angle 90 degrees and radius L. This is a microstrip radial stub. What is the maximum radius if the line input impedance is not to go to infinity at 300 GHz ? What is the low-frequency capacitance of this stub?
4 Problem 3 Here is a simple small-signal MOSFET model, except that C3 (Cgd) is unrealistically small. Making it exactly zero again causes some numerical problems. 1) Design series-stub, shunt-stub matching networks for the input and output. Using high-Z lines of 5 microns width and low-Z lines of 50 microns width, design matching networks on input and output at 100 GHz signal frequency. 2) Determine the line impedances and velocities using the methods of problem 1, and then compute the Pi-section models. Ignoring the capacitance of the high-Z lines and the inductance of the low-Z lines, draw the resulting lumped LC matching network.
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