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Calibration and Error Correction for Compression and IMD Measurement

Question asked by AndyL on Apr 20, 2018
Latest reply on May 7, 2018 by Dr_joel



I am planning to use PNA-X N5247A to characterize an amplifier chip with wafer probes. I would like to use the PNA-X to do most of the characterizations (S-parameters, AM-AM, AM-PM, IMD). Our machine is a 4-port configuration with most of the options (400, 419, 423, 010, 080, 083, 084, 020) but do not have the optiosn 086 & 087 installed. Here are the questions and understandings that I have on calibration :


1.1) S-parameter measurement

   For general S-parameter measurement, we have calibration substrate and will do the calibration up to the probe so that the reference place will be at the probe tip and S-parameter of the DUT (including the probe pad which is designed to be part of the amplifier) can be characterized.

1.2) AM-AM, AM-PM and compression measurement  

Power calibration will be needed and I plan to do the guided power and receiver calibration and use receiver leveling to control the incident power to the DUT. However because the DUT is probed while the power sensor cannot be connected to the probe tip. Therefore the following will be the steps that I will be taking

   i) Do a 2 Tier 2-port SOLT calibration. Tier 1 is at the probe tip using the calibration substrate and Tier 2 is at the end of the coaxial that will be connected to the probe and power sensor. During the Tier 2 calibration, power and receiver calibration will be done as well using the guided power calibration procedure.

  ii) Using the Cal Plane Manager, we can generate the fixture (wafer probe) S-parameter file from the calset of Tier 1 & Tier 2 calibration.

  iii) Use the fixture simulator with the fixture S-parameter file obtained in ii) to de-embed the fixture; also enable power compensation so that match corrected power calibration is up to the probe tip.

iv) Enable receiver leveling and proceed with the measurement.


  - Are the above steps to preferred way (most accurate and easy) to do the calibration for compression type of measurement in a wafer probe environment ?

  - For the power compensation enabled in step iii) using the fixture simulator, will it be a match corrected receiver calibration or just a response type of receiver calibration ? I would like to have match corrected receiver calibration up to the probe tip.

  - During the guided power calibration, there is an option to "deembed the power sensor adaptor". Could this be used to achieve the goal that I want and what is the exact steps ?


1.3) IMD measurement

Frequency offset mode will be needed for this measurement. Below are my questions :

i) What is the best way to do the power and receiver calibration that is match corrected in this case ? Could I use the guided power and receiver calibration as in 1.2) above ? The reason I am asking is because in PNA-X help, it mentioned that the guided power calibration is not accurate in frequency offset mode (FOM). However, since I am not measuring frequency converter, I see no reason why this cannot be applied and in fact the receiver leveling seems to be able to work in FOM.

ii) Another conceptual question that I have is does the receiver leveling works in the two-tone cases ? Does it level the two sources separately or combined before each sweep ?


Finally after reading the book "Handbooks of Microwave Components Measurement" (which is very helpful in my understanding of the recent advances in network analyzer), I have the  following questions on match corrected calibration for Dr Joel.


1) In equation (3.45) on page 161, the calculation of STF for calibration for sensor mismatch requires the knowledge of a1s which is given  in Eq (3/46) as function of match of the power source, which is not known in general. Does that mean that the match corrected source power calibration still depends on DUT mismatch ? I take it that receiver leveling is the best way for match corrected incident power control

2) In guided power calibration, the power and receiver calibration is before the 2-port calibration while the results of the latter are required to compute RRF and STF. How are the sequence in which these done actually ?

3) Could I get the match corrected source power and receiver calibration done without using the guided power calibration ? Is it actually just a matter of  following the correct sequence of calibration, like power source, receiver and 2 port calibration.



Sorry for the many questions and appreciate your feedback and help,