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Fixture Measurements. Doug Rytting. Agenda. Agilent Network Analysis Applying the 8510 TRL Calibration for Non-Coaxial Measurements Product Note 8510-8A Agilent De-embedding and Embedding S-Parameter Networks Using a Vector Network Analyzer Product Note 8510-8A
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Fixture Measurements Doug Rytting
Agenda • Agilent Network Analysis Applying the 8510 TRL Calibration for Non-Coaxial Measurements • Product Note 8510-8A • Agilent De-embedding and Embedding S-Parameter Networks Using a Vector Network Analyzer • Product Note 8510-8A • In-Fixture Measurements Using Vector Network Analyzers • Agilent AN 1287-9 • Other • Asymmetrical Reciprocal Optimization • Two-Tier Calibration and Simplified Error Models
Content of Application Note • TRL Calibration in Fixture • TRL Calibration on PC Board
Agenda • Agilent Network Analysis Applying the 8510 TRL Calibration for Non-Coaxial Measurements • Product Note 8510-8A • Agilent De-embedding and Embedding S-Parameter Networks Using a Vector Network Analyzer • Product Note 8510-8A • In-Fixture Measurements Using Vector Network Analyzers • Agilent AN 1287-9 • Other • Asymmetrical Reciprocal Optimization • Two-Tier Calibration and Simplified Error Models
Content of Application Note • De-embed Process • De-embed using ADS models
Measured vs Modeled FixtureOptimize until Modeled Matches Measured
Agenda • Agilent Network Analysis Applying the 8510 TRL Calibration for Non-Coaxial Measurements • Product Note 8510-8A • Agilent De-embedding and Embedding S-Parameter Networks Using a Vector Network Analyzer • Product Note 8510-8A • In-Fixture Measurements Using Vector Network Analyzers • Agilent AN 1287-9 • Other • Asymmetrical Reciprocal Optimization • Two-Tier Calibration and Simplified Error Models
Content of Application Note • Practical Considerations for Fixture Calibrations. • Time Domain Used to Reduce Errors.
Agenda • Agilent Network Analysis Applying the 8510 TRL Calibration for Non-Coaxial Measurements • Product Note 8510-8A • Agilent De-embedding and Embedding S-Parameter Networks Using a Vector Network Analyzer • Product Note 8510-8A • In-Fixture Measurements Using Vector Network Analyzers • Agilent AN 1287-9 • Other • Asymmetrical Reciprocal Optimization • Two-Tier Calibration • Simplified Error Models
Asymmetrical Reciprocal Optimization • A passive asymmetrical reciprocal device is used in addition to short, open, load, and thru standards. • The errors in calibration kit parameters can be reduced through numerical optimization to minimize asymmetry after correction. • There are some potential convergence issues.
Transmission Line Optimized Calibration • Measure S21m of a long transmission line. • Calculate S11c=S21mS21m of the transmission line. • Measure S11m of the transmission line with short connected to the end. • Subtract S11c from S11m for comparison. • Adjust capacitance of open to minimize ripple. • Adjust inductance of load and short to match the calculated S11c and measured S11m of the transmission line. • If possible, connect the load on the end of the long transmission line and adjust inductance of the load model for best performance. Then adjust the open and short models using a short connected to the end of the long transmission line.
Transmission Line Optimized CalibrationCoax example using a 10 cm verification airline with a short on the end.Before and after optimizing the calibration standard’s models.Same approach can be used for fixture and on wafer measurementsusing a long verification transmission line.
Two-Tier Calibration • First tier calibration stored in network analyzer. • Second tier calibration performed with first tier calibration turned on. • First tier could be SOLT and second tier TRL. This method enables TRL calibration on a 3 receiver NA. • First tier could be at coax port of NA and second tier at ports of a fixture This process will characterize the fixture.
Simplified Error Model for FixtureUsing Two-Tier Technique • Allows simpler second tier calibrations since number of error terms reduced from 7 to 6 due to reciprocity of the fixture. • For example, SOLT can be simplified to SOL since no thru is required. • Once fixture is characterized the data can be stored and used in future calibrations. • Many other simplified fixture calibrations are available.