ECE145A/218A Notes Set #4 3 Rev.11/07 Prof. S. Long/ECE/UCSB Impedance Parameters V1V2⎡ ⎣ ⎢ ⎤ ⎦ ⎥ =Z11Z12Z21Z22⎡ ⎣ ⎢ ⎤ ⎦ ⎥ I1I2⎡ ⎣ ⎢ ⎤ ⎦ ⎥ Example R1R3R2By inspectionZ=R1+R3R3R3R2+R3⎡ ⎣ ⎢ ⎤ ⎦ ⎥ 121121110022IIVVZZII====But, y, z, and hparameters are not suitable for high frequency measurement. Problem: How can you get a true open or short at the circuit terminals? Any real short is inductive. Any real open is capacitive. To make matters worse, if you are trying to measure a high freq. active device, a short or open can make it oscillate! Solution: Use termination in Z0instead! Broadband. Not very sensitive to parasitic L,C Kills reflections. Redefine parameters to use fwd. and rev. voltage waves. Measurement can use directional couplers.