Post by Professor Lake Shore on Jan 31, 2017 17:16:48 GMT -5
I am looking for information about calibrating my VNA for microwave measurements in a Lake Shore probe station. Are there any general recommendations on calibration methods?
To calibrate out the dispersion and losses of the probes as well as probe station and network analyzer cabling, most network analyzers support a SOLT (short-open-load-through) calibration. For probing measurements, a CS-5 on-wafer calibration substrate (available from Lake Shore) is used as the reference standard for the calibration. Before performing the calibration at a given sample stage temperature, GSG probes should be planarized to the calibration substrate. Once the prober has been calibrated, the frequency-dependent S-parameters of your wafer-level DUT can be determined. The SOLT calibration method is sufficient for most conventional microwave on-wafer probing applications below 20 GHz. For higher-frequency measurements, however, other calibration methods may be necessary. Above 20 GHz, the SOLT method is extremely sensitive to consistent probe placement and contact pressure in order to achieve an accurate calibration. For better S-parameter accuracy at higher frequencies, Lake Shore recommends TLR (thru-reflect-line) or LRRM (line-reflect-reflect-match) on-wafer calibration techniques to reduce the impact of probe placement errors. These calibrations can be carried out using the WinCal software package in conjunction with calibration substrates from Cascade Microtech. However, the LRRM calibration method is more sensitive to the variation in load standard; for cryogenic measurements, the temperature-dependent load resistance should be measured and compensated in the calibration calculation. For more information, visit the Cascade Microtech website or contact Lake Shore.