6-48
Calibrating for Increased Measurement Accuracy
Making Non-Coaxial Measurements
Making Non-Coaxial Measurements
Non-coaxial, on-wafer measurements present a unique set of challenges for error
correction in the analyzer:
• The close spacing between the microwave probes makes it difficult to maintain a high
degree of isolation between the input and the output.
• The type of device measured on-wafer is often not always a simple two-port.
• It may be difficult to make repeatable on-wafer contacts due to the size of the device
contact pads.
The capability of making non-coaxial measurements is available with TRL
(thru-reflect-line) or LRM (line-reflect-match) calibration. For in-depth information on
TRL/LRM calibration, refer to "Calibrating for Non-Coaxial Devices (ES Analyzers Only)"
on page 6-50.
Due to the simplicity of the calibration standards, TRL or LRM calibrations may be used
for non-coaxial applications such as on-wafer measurements. This type of calibration with
time-domain gating and a variety of probe styles can provide optimal accuracy in on-wafer
measurements.
NOTE Full TRL/LRM calibration is available on instruments equipped with Option
400, four sampler test set. TRL*/LRM* is available on standard instruments.

Fixtures

Fixtures are needed to interface non-coaxial devices to coaxial test instruments. It may
also be necessary to transform the characteristic impedance from standard 50 Ω
instruments to a non-standard impedance and to apply bias if an active device is being
measured.
For accurate measurements, the fixture must introduce minimum change to the test
signal, not destroy the test device, and provide a repeatable connection to the device.
For information about test fixtures for your measurement systems, ask for literature
number 5962-9723E or contact: Inter-Continental Microwave, 1515 Wyatt Drive, Santa
Clara, CA 95054, USA (Web site: http://www.icmicrowave.com).