Development of enhanced multiport network analyzer calibrations using non-ideal standards

An Improved Short-Open-Load-Reciprocal (SOLR) Vector Network Analyzer (VNA) calibration is developed and validated. Through the use of a more complex load model the usable frequency range of the SOLR calibration algorithm is expanded. Comparisons are made between this new calibration and existing calibration techniques that are known to be accurate at high frequencies. The Anritsu 37xxx Lightning series 65GHz VNA is used as the principle measurement tool for calibration comparison and verification. This work is built off of previous work done at USF in which it is shown that the Short-Open-Load-Thru (SOLT) calibrations accuracy improves through the implementation of more complex load and thru models. One of the most significant advantages of the SOLR calibration algorithm is that it does not require an ideal well behaved thru standard. This is extremely useful in multiport probing environments where it is often necessary for speed and space conservation purposes to use loopback thrus or other non-ideal transmission structures during calibration. Multiport test equipment and measurement techniques are highlighted and discussed. A general n-port expansion of a two-port calibration algorithm is presented and used to adapt the improved two-port SOLR algorithm to a four-port calibration. In doing so a theoretical development that addresses error model treatment, and switch term corrections is presented that includes an improved set of the redundancy equations that enable the multiport SOLR algorithm. The algorithm uses a four-port SOL calibration at each port and then determines the remaining error terms by measuring a minimal set of reciprocal passive standards. The four-port SOLR algorithm developed was illustrated through the use of a four-port test set that consists of a two-port VNA input multiplexed to four-ports through an RF switch array. Verification of the four-port SOLR calibration is made by comparing it to available four-port calibration techniques using available on-wafer test structures. As another promising advance of the work the possibility of using of a multiport reciprocal standard is shown to have potential for reducing the number of standard connections needed to accomplish multiport SOLR calibration. Differential measurements are facilitated through mixed-mode calculations of single ended S-parameter measurements made with the four-port SOLR calibrations improved with this work