De-embedding comparisons of 1X-Reflect SFD, 1-port AFR, and 2X-Thru SFD

Chen, Yuan; Chen, Bichen; He, Jiayi; Zai, Richard; Fan, Jun; Drewniak, James L.

doi:10.1109/isemc.2018.8393759

“…Recently, the 2x-thru calibration [5][6][7][8][9][10][11][12][13][14][15] has emerged as an attractive alternative to the TRL due to its simplicity. The basic version of 2x-thru assumes symmetric fixtures, but requires the measurement of FDUT and THRU only.…”

Section: Introductionmentioning

confidence: 99%

“…In our opinion, there are two problems regarding the current understanding of the Zref in 2x-thru calibration. First, there is a lack of a thorough explanation as for how Zref is set to ZLINE during the calibration process, and correspondingly, the physical meaning of the resulting S parameters in terms of the traveling wave and pseudowave [11] has never been clarified. The importance of the wave concept is that it will determine how the calibrated S parameters should be used, as ignorance of it may lead to inappropriate calibration practice.…”

Section: Introductionmentioning

confidence: 99%

The Reference Impedance in 2x-thru Calibration, and its Estimation for High Conductor-loss Transmission Lines

Chou¹

2022

Preprint

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<p>The 2x-thru calibration has emerged as an attractive alternative to the classical TRL for S parameter measurement of printed circuit board and packaging devices, due to its simplicity that only one THRU standard suffices to fully characterize the test fixtures, thus eliminating the LINE measurement in TRL and also overcoming the bandwidth limit. Although various 2x-thru calibration tools are available nowadays, there are still some issues that have not been studied in detail. This paper addresses the following two fundamental questions: (i) what is the reference impedance (Zref) of the S parameters after 2x-thru calibration? (ii) what is the time-domain reflectometry (TDR) response of the THRU for high conductor-loss transmission lines, and how to estimate Zref given such TDR? For problem (i), we rigorously show that the Zref is equal to the characteristic impedance of the center transmission line in the THRU standard, and provide the important interpretation for the S parameters in terms of the traveling-wave and pseudowave concepts. For problem (ii), we show that the TDR impedance is a monotonically increasing function instead of constant, and we propose a new method to estimate the characteristic impedance by fitting the TDR with a causal impedance model. Simulation and measurement examples are provided to validate the proposed theory and techniques. In the last example, we also compare five commercial/open-source 2x-thru calibration tools; the results reveal that with the proposed method of impedance estimation, better accuracy can be achieved. </p>

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“…An effective method relies on the construction of the 2Â-Fixture, where both left and right fixtures are designed next to each other and measured. The smart fixture de-embedding (SFD) 10 and the automatic fixture removal (AFR) described in reference 11 and available in reference 12 can be applied for the 2-port 2Â-fixture case. The SFD has been extended up to 8-port for differential lines in reference 13, and to a generic 2 n port number in reference 14.…”

Section: Introductionmentioning

confidence: 99%

Generalized analytical formulation for de‐embedding of multiport devices based on known fixtures

Scafati

¹

,

Paulis

²

,

Olivieri

³

et al. 2022

Int J RF Mic Comp-Aid Eng

1

0

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The de-embedding is a technique used in radio frequency and signal integrity measurements to extract the scattering (S)-parameters of the device under test (DUT) from the measured data of a global assembly and based on known S-parameters of the left and right test fixtures; thus, it removes the impact of the text fixtures used for the connection of the DUT to the instrumentation. Once the S-parameters are measured, the de-embedding is performed by a multistep approach involving the bidirectional transformation of the S-parameters into the corresponding transfer scattering (T)-parameters. The latter approach is well established for two-and four-port networks and has been recently expanded to the multiport case. This work proposes an alternative analytical formulation to de-embed a multiport device, knowing in advance only the S-parameters of the global multiport assembly and those of the test fixtures. The proposed method does not involve the S-to-T conversion and it requires only the algebraic manipulation of the S-parameter matrix elements; its practical implementation is very well fitted especially for multiport cases, and it is very fast in calculating the de-embedded DUT S-parameters for large port numbers. The results of the proposed formulation, applied to the case of a multipin high-speed connector, are compared with those obtained by measurement and simulations.Their accuracy is shown and discussed to demonstrate the validity of the proposed approach.

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“…Recently, the 2x-thru calibration [5][6][7][8][9][10][11][12][13][14][15] has emerged as an attractive alternative to the TRL due to its simplicity. The basic version of 2x-thru assumes symmetric fixtures, but requires the measurement of FDUT and THRU only.…”

Section: Introductionmentioning

confidence: 99%

The Reference Impedance in 2x-thru Calibration, and its Estimation for High Conductor-loss Transmission Lines

Chou¹

2022

Preprint

0

View full text Add to dashboard Cite

<p>The 2x-thru calibration has emerged as an attractive alternative to the classical TRL for S parameter measurement of printed circuit board and packaging devices, due to its simplicity that only one THRU standard suffices to fully characterize the test fixtures, thus eliminating the LINE measurement in TRL and also overcoming the bandwidth limit. Although various 2x-thru calibration tools are available nowadays, there are still some issues that have not been studied in detail. This paper addresses the following two fundamental questions: (i) what is the reference impedance (Zref) of the S parameters after 2x-thru calibration? (ii) what is the time-domain reflectometry (TDR) response of the THRU for high conductor-loss transmission lines, and how to estimate Zref given such TDR? For problem (i), we rigorously show that the Zref is equal to the characteristic impedance of the center transmission line in the THRU standard, and provide the important interpretation for the S parameters in terms of the traveling-wave and pseudowave concepts. For problem (ii), we show that the TDR impedance is a monotonically increasing function instead of constant, and we propose a new method to estimate the characteristic impedance by fitting the TDR with a causal impedance model. Simulation and measurement examples are provided to validate the proposed theory and techniques. In the last example, we also compare five commercial/open-source 2x-thru calibration tools; the results reveal that with the proposed method of impedance estimation, better accuracy can be achieved. </p>

show abstract

De-embedding comparisons of 1X-Reflect SFD, 1-port AFR, and 2X-Thru SFD

Cited by 21 publications

References 9 publications

The Reference Impedance in 2x-thru Calibration, and its Estimation for High Conductor-loss Transmission Lines

The Reference Impedance in 2x-thru Calibration, and its Estimation for High Conductor-loss Transmission Lines

Generalized analytical formulation for de‐embedding of multiport devices based on known fixtures

The Reference Impedance in 2x-thru Calibration, and its Estimation for High Conductor-loss Transmission Lines

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