Service manual

8510XF Network Analyzer Systems 3-7
Operation
Measurement Calibration
NOTE The shorts used in the 85059A 1.0 mm calibration kit are offset shorts.
When measured, the offset shorts will exhibit the characteristics of a flush
short that is placed at the end of an airline (there will be a change in phase
and an increasing amount of loss with increasing frequency).
Another practice is to measure a device that had been measured with a
previous good calibration, and compare the present measurement to the
earlier one (if there are any changes exceeding the limits of acceptable
accuracy, a new calibration is needed). For example, measure one of the
verification devices that was used during performance verification, and
compare it to the data that was taken at that time.
However, these methods give only an approximate confirmation that the
calibration is good. The only way to make an accurate check is to run the
8510C Specification and Performance Verification software, which runs on a
PC or controller (the procedure for this is presented in Chapter 4,
“Performance Verification”).
Calibration
Techniques
A variety of calibration techniques can be used with the 8510XF, including
the following:
• SOLT (Short-Open-Load-Thru)
• Offset Shorts (Shorts with different offset lengths)
• TRL (Thru-Reflect-Line)
• TRM (Thru-Reflect-Match)
The calibration technique used depends in part on the type of calibration kit
used. The 1.0 mm calibration kit (85059A), which was designed specifically
for the 8510XF, uses a combination of two calibration techniques (SOLT
calibration, for frequencies up to 50 GHz, and Offset Shorts calibration, for
frequencies above 50 GHz). This combination of techniques provides the
best possible calibration results on the 8510XF.
Types of Calibration
Kits
1.0 mm calibration kit
The calibration procedures in this chapter are based on the assumption that
the 1.0 mm coaxial calibration kit (85059A) will be used to calibrate the
system. This kit was designed specifically for the 8510XF, and provides
coverage over a frequency range of 45 MHz to 110 GHz. (The standards in
the kit have 1.0 mm coaxial connections; they cannot be used for on-wafer
measurement calibration.) Refer to the 85059A calibration kit manual for
more information (part number 85059-90003).
NOTE If a calibration kit other than the 85059A is used, please refer to the
documentation for that kit.