3.13 Impedance Measurements

3.13 Impedance Measurements

There are a number of measurement techniques (instruments) available for L, C, and R measurements which include using an Auto Balancing Bridge, Resonant (Q-adapter/Q-Meter), I-V (Probe), RF I-V, Network Analysis (Reflection Coefficient), and TDR (Time Domain Reflectometry). The selection criteria depend on frequency coverage, DUT impedance, required measurement accuracy, electrical test conditions, measurement parameters, and the physical characteristics of the DUT -- and as always, trade-offs are involved. Often the DUT's impedance range is completely ignored, which leads to big discrepencies with the measurement result expectations. Another key point is that different techniques have different measurement accuracy under the same operating conditions. In general, all the techniques are good and come with their share of advantages and disadvantages. In some cases, using multiple techniques may be required.

For information on L, C, and R characterization and a discussion of some of the various measurement techniques available, see References [1], [2], [3], [4], [5].


[1] Hewlett-Packard Company, 1997 Back to Basics Seminar (HP publication number 5965-7008E) http://www.tmo.hp.com/tmo/

[2] Hewlett-Packard Company, Effective Test Methods for Today's RF Devices (HP publication number 5963-5191E)

[3] Hewlett-Packard Company, RF and Microwave Device Test for the '90s Seminar Papers (HP publication number 5963-5191E)

[4] Coilcraft Catalog, Testing Inductors at Application Frequencies.

[5] C. Patrick Yue and S. Simon Wong, "On-Chip Spiral Inductors with Patterned Ground Shields for Si-Based RF IC's", IEEE Journal of Solid Circuits, Vol. 33, No. 5, May 1998


Back to Test Guide Table of Contents