• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
S-Parameter Calibration of Two-Port Setup
 

S-Parameter Calibration of Two-Port Setup

on

  • 2,900 views

 

Statistics

Views

Total Views
2,900
Views on SlideShare
2,557
Embed Views
343

Actions

Likes
0
Downloads
44
Comments
0

3 Embeds 343

http://blog.cmicro.com 292
http://www.cascademicrotech.com 49
http://feeds.feedburner.com 2

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    S-Parameter Calibration of Two-Port Setup S-Parameter Calibration of Two-Port Setup Presentation Transcript

    • S-Parameter Calibration of Two-Port Setup: How to choose the optimal calibration method? Gavin Fisher Cascade Microtech Wafer-Level S-Parameter Calibration Techniques
    • Content  Error Modeling of a two-port setup  Calibration methods – SOLT  Self-calibration routine: – SOLR – LRM/LRM+ – LRRM  Conclusion Wafer-Level S-Parameter Calibration Techniques•Slide 2
    • Error Modeling of a Two Port Setup  Influencing Factors: – VNA architecture – Crosstalk between ports  Commonly used models: – 10(12) Terms – 7(8) Terms – 15(16) Terms Wafer-Level S-Parameter Calibration Techniques•Slide 3
    • Reference Channel VNA  N=n+1 receivers  10(12)-term error model m1 a1 1 [E] 1 I m2 b1 DUT II m2 m3 a2 [Sx] 2 m1, m2 [F] 2 m4 b2 m4 where : N - number of receivers n - number of ports Wafer-Level S-Parameter Calibration Techniques•Slide 4
    • Double Reflectometer VNA  N=2n receivers  7(8)-term or 10-term (converted) model m1 a1 1 [A] 1 m2 b1 DUT I m1 m2 m3 a2 [Tx] II 2 [B1]-1 2 m4 b2 m3 m4 where : N - number of receivers n - number of ports Wafer-Level S-Parameter Calibration Techniques•Slide 5
    • 10-Term Model Reflection terms: Transmission terms: – Directivity, ED - Transmission tracking, ET – Source match, ES - Load match, EL – Reflection tracking, ER - Crosstalk, EX Forward direction: EX m1 a1 b2 m4 1 S21 ET ED ES S11 S22 EL m2 b1 a2 ER S12 Wafer-Level S-Parameter Calibration Techniques•Slide 6
    • SOL Calibration m1 a  Reflection measurements: 1 ED S11M  E D ES SA S11A    m2 ER b E S S11M  E D  E R • Three independent measurement conditions: 1: ED  S11A S11M ER  S11A ED ES  E R   S11M I I I I 2: ED  S11A S11M ER  S11A ED ES  E R   S11M II II II II 3: ED  S11A S11M ER  S11A ED ES  E R   S11M III III III III • Commonly used standards: - Short, Open, Load (SOL) Wafer-Level S-Parameter Calibration Techniques•Slide 7
    • Experiment Error Correction Wafer-Level S-Parameter Calibration Techniques•Slide 8
    • Wincal / SOL demonstration  Objective: – To show how calibration (and Wincal) works  Verification conditions – Verification series: same standards  Experimental Conditions: – Regular SOL calibration and measurement of standard  Observation: – How to use Wincal to apply calibration and show use of Wincal processing raw data directly Wafer-Level S-Parameter Calibration Techniques•Slide 9
    • Wincal / SOL demonstration  In this example we will be using Wincal with measured data to perform the measurement, but the data has been measured previously  Screen shots are shown in case existing Wincal users may want to use the same techniques for off line processing of raw measurement Wafer-Level S-Parameter Calibration Techniques•Slide 10
    • Wincal / SOL demonstration  Folder set-up is done in order for Wincal to find the raw data for process under calibration.  Note - MeasFiles folder used to store raw measurements  Files have Vmeas_ as start of file name to denote Wincal will process the raw measurement. Wafer-Level S-Parameter Calibration Techniques•Slide 11
    • Wincal / SOL demonstration  Wincal system set-up restores default conditions of instrument, probes, stimulus etc Wafer-Level S-Parameter Calibration Techniques•Slide 12
    • Wincal / SOL demonstration  Opening the calibration set-up allows the old calibration state to be restored, including measurements if present Wafer-Level S-Parameter Calibration Techniques•Slide 13
    • Wincal / SOL demonstration  With the cal loaded we can hit compute which calculates the error terms as discussed. Normally we would send these to the instrument Wafer-Level S-Parameter Calibration Techniques•Slide 14
    • Wincal / SOL demonstration  Hitting the measure button brings up a new blank report  We can store hundreds of individual measurements in a single report Wafer-Level S-Parameter Calibration Techniques•Slide 15
    • Wincal / SOL demonstration  From the report window we can open pre-saved reports with preset viewing and processing options Wafer-Level S-Parameter Calibration Techniques•Slide 16
    • Wincal / SOL demonstration  Wincal can either take a measurement from an instrument or use the currently applied cal to correct a named raw measurement in the measurement folder Wafer-Level S-Parameter Calibration Techniques•Slide 17
    • Wincal / SOL demonstration  Here we have S-parameter measurements of the SOL standards used for the calibration and also an additional open standard which is on wafer and has positive capacitance Wafer-Level S-Parameter Calibration Techniques•Slide 18
    • Wincal / SOL errors  Objective: – To show effect of standard misplacement and other errors  Verification conditions – Verification series: same standards for cal  Experimental Conditions: – Regular SOL calibration and measurement of standard  Observation: – How SOL is only as good as the standards you measure Wafer-Level S-Parameter Calibration Techniques•Slide 19
    • Wincal / SOL errors  New calibration loaded  Same standards for cal re-measured (Short / Open iss)  Independent standard re-measured (Air open)  Spot the problem..... Wafer-Level S-Parameter Calibration Techniques•Slide 20
    • SOL Calibration – Recap.. m1 a  Reflection measurements: 1 ED S11M  E D ES SA S11A    m2 ER b E S S11M  E D  E R • Three independent measurement conditions: 1: ED  S11A S11M ER  S11A ED ES  E R   S11M I I I I 2: ED  S11A S11M ER  S11A ED ES  E R   S11M II II II II 3: ED  S11A S11M ER  S11A ED ES  E R   S11M III III III III • Commonly used standards: - Short, Open, Load (SOL) Wafer-Level S-Parameter Calibration Techniques•Slide 21
    • SOLT Calibration  10 unknowns have to be defined – Step 1. SOL on Port 1 and 2:    ED , ES , ER , and   ED , ES , ER  - Step 2. Connect two port together (“Thru”):  S11M  ED  EL  ET  S21M 1  ES EL     S11M ES  ED ES  ER      - From reverse direction: EL , EF   prime, double-prime parameters correspond to the forward and reverse measurement directions respectively. Wafer-Level S-Parameter Calibration Techniques•Slide 22
    • Calibration Standard Requirements THRU OPEN SHORT LOAD Known: Known: Known: Known: S11, S21, S12, S22 S11 (S22) S11 (S22) S11** (S22) Example: THRU OPEN SHORT LOAD Z0=50Ω R=inf R=0 R=50 α=0, τ=0.5pS C=0.3fF L=9pH L=10.6pH Wafer-Level S-Parameter Calibration Techniques•Slide 23
    • Experiment SOLT Wafer-Level S-Parameter Calibration Techniques•Slide 24
    • SOLT Experiment  Objective: – To prove sensitivity to standard models  Verification conditions: – Series of CPW different length  Experimental Conditions A: – Define wrong OSL coefficients (different probe type/pitch)  Observation: – Accuracy decreases with the frequency, RF “noise” on S21  Experimental Condition B: – Define extracted data-file models for OSL standards  Observation – SOLT is as good as you know your standards Wafer-Level S-Parameter Calibration Techniques•Slide 25
    • SOLT Experiment  Wincal settings loaded from file  Calibration settings loaded from file  Calibration populated with measurements and calculated  Measurements of line standards carried out Wafer-Level S-Parameter Calibration Techniques•Slide 26
    • SOLT Experiment Wafer-Level S-Parameter Calibration Techniques•Slide 27
    • SOLT Experiment  Looking at coefficients Wafer-Level S-Parameter Calibration Techniques•Slide 28
    • SOLT Experiment  Open / Load standards look as they should Wafer-Level S-Parameter Calibration Techniques•Slide 29
    • SOLT Experiment  But Lines look terrible Wafer-Level S-Parameter Calibration Techniques•Slide 30
    • SOLT Experiment  Load inductance now set to correct value Wafer-Level S-Parameter Calibration Techniques•Slide 31
    • SOLT Experiment  Comparison between same line different calibration Wafer-Level S-Parameter Calibration Techniques•Slide 32
    • Content  Error Modeling of a two-port setup  Calibration methods – SOLT  Self-calibration routine: – SOLR – LRM/LRM+ – LRRM  Conclusion Wafer-Level S-Parameter Calibration Techniques•Slide 33
    • Self Calibration  Requires double reflectometer VNA  Two error matrices [A] and [B] of [T] parameters  7 error terms are in use (normalized to A22)  More information is measured than required  This additional information allows some parameters to be calculated from within the calibration routine m1 a1 1 [A] 1 Ideal m2 b1 DUT VNA m3 a2 [Tx] -1 2 [B ] 2 m4 b2 1  m1 m1   A11 A12  T11 T12  B11 B12   m3 m3         m  2 m2   A21   A22  21 T22  B21  T  B22   m  4  m4  Wafer-Level S-Parameter Calibration Techniques•Slide 34
    • Self Calibration (cont.)  Measured matrix: 1 m m  m m  M  1 1  3 3  , M X  ATX B 1 m  m   2 m 2  4 m 4  • Three measurement conditions give [A] and [B]: Standard Requirements Definitions T1 Fully known 4 T2 Maximum of two free parameters 2 T3 Maximum of three free parameters 1 H. J. Eul and B. Schiek, "A generalized theory and new calibration procedures for network analyzer self-calibration," Microwave Theory and Techniques, IEEE Transactions on, vol. 39, pp. 724-731, 1991. Wafer-Level S-Parameter Calibration Techniques•Slide 35
    • SOLR  Standards used: – Reflection: Short, Open, Load – Transmission: Reciprocal Standard Requirements Definitions Short S11, S22 : known 2 Open S11, S22 : known 2 Load S11, S22 : known 2 Reciprocal unknown, S21=S12 1 A. Ferrero and U. Pisani, "Two-port network analyzer calibration using an unknown `thru," Microwave and Guided Wave Letters, IEEE, vol. 2, pp. 505-507, 1992. Wafer-Level S-Parameter Calibration Techniques•Slide 36
    • Experiment SOLR Wafer-Level S-Parameter Calibration Techniques•Slide 37
    • SOLR Experiment  Objective: – To prove sensitivity to standard models  Verification conditions: – Series of CPW different length  Experimental Conditions A: – Define wrong OSL coefficients (different probe type/pitch)  Observation: – Accuracy decrease with the frequency  Experimental Condition B: – Define extracted data-file models for OSL standards  Observation – SOLR is as good as you know your OSL standards Wafer-Level S-Parameter Calibration Techniques•Slide 38
    • SOLR Experiment  SOLR line measurements using initial value for load inductance Wafer-Level S-Parameter Calibration Techniques•Slide 39
    • SOLR Experiment  Calibration carried out again with correct probe definitions. Correction applied to original data Wafer-Level S-Parameter Calibration Techniques•Slide 40
    • Content  Error Modeling of a two-port setup  Calibration methods – SOLT  Self-calibration routine: – SOLR – LRM/LRM+ – LRRM  Conclusion Wafer-Level S-Parameter Calibration Techniques•Slide 41
    • LRM and LRM+  Standards used: – Transmission: Thru (Line) – Reflection: Load (Match), Reflect Standard Requirements Definitions Thru/Line Fully known 4 Load/Match S11, S22 : known 2 Reflect unknown, S11=S22 1 H. J. Eul and B. Schiek, "Thru-Match-Reflect: one result of a rigorous theory for de-embedding and network analyzer calibration," in European Microwave Conference, 18th, B. Schiek, Ed., 1988, pp. 909-914. Wafer-Level S-Parameter Calibration Techniques•Slide 42
    • LRM vs. LRM+  Differ in requirements for Load standard: – LRM for coaxial applications – LRM+ for on-wafer calibration Method Load R X LRM Known R1=R2=50Ω 0 LRM+ Known R 1, R 2 X1, X2 Arbitrary Arbitrary R. F. Scholz, F. Korndorfer, B. Senapati, and A. Rumiantsev, "Advanced technique for broadband on-wafer RF device characterization," in ARFTG Microwave Measurements Conference-Spring, 63rd, 2004, pp. 83-90. Wafer-Level S-Parameter Calibration Techniques•Slide 43
    • Experiment LRM/LRM+ Wafer-Level S-Parameter Calibration Techniques•Slide 44
    • LRM/LRM+ Experiment 1  Objective: – To prove sensitivity to the Load  Verification conditions: – Open, Short, Load, CPW’s  Experimental Conditions A: – Asymmetrical Load  Observation: – Offset in reflection coefficient for high-reflective elements Wafer-Level S-Parameter Calibration Techniques•Slide 45
    • LRM/LRM+ Experiment 1  Calibration applied for LRM+ and measurements computed  LRM is calculated and the same raw data is computer with LRM  For both calibrations Reflect was short so open makes good validation structure  Loads were assymetric – RH was 49 ohms which LRM+ is set up for Wafer-Level S-Parameter Calibration Techniques•Slide 46
    • LRM/LRM+ Experiment 1  LRM shows divergence in Port1 and Port 2 Open (not used in cal) due to load inductance assymetry Wafer-Level S-Parameter Calibration Techniques•Slide 47
    • LRM/LRM+ Experiment 2  Objective: – To prove sensitivity to the Load  Verification conditions: – Open, Short, Load, CPW’s  Experimental Conditions A: – Load as a resistor (50 Ohm)  Observation: – Impact of Zref Wafer-Level S-Parameter Calibration Techniques•Slide 48
    • LRRM  Standards used: – Transmission: Thru (Line) – Reflection: Reflect(Open), Reflect(Short), Load(Match) Standard Requirements Definitions Thru/Line Fully known 4 Reflect (Open) unknown, S11=S22 1 Reflect(Short) unknown, S11=S22 1 Load(Match) S11 (or S22) known 1 A. Davidson, K. Jones, and E. Strid, "LRM and LRRM calibrations with automatic determination of load inductance," in ARFTG Microwave Measurements Conference-Fall, 36th, 1990, pp. 57-63. Wafer-Level S-Parameter Calibration Techniques•Slide 49
    • LRRM(cont.)  Requirements to the Load standard Load Impedance R L Inductance approximation Known Arbitrary, Z = R+jωL unknown • Unknown L can be found by the automated load inductance extraction algorithm L. Hayden, "An enhanced Line-Reflect-Reflect-Match calibration," in ARFTG Microwave Measurements Conference-Spring, 67th, 2006, pp. 143-149. Wafer-Level S-Parameter Calibration Techniques•Slide 50
    • Experiment LRRM Wafer-Level S-Parameter Calibration Techniques•Slide 51
    • LRRM Experiment 1  Objective: – To show LRRM relative immunity to probe misplacement  Verification conditions: – CPW’s  Experimental Conditions A:  Observation: – Line measurements comparatively immune to probe misplacement Wafer-Level S-Parameter Calibration Techniques•Slide 52
    • Probes in normal position Wafer-Level S-Parameter Calibration Techniques•Slide 53
    • Probes misplaced Wafer-Level S-Parameter Calibration Techniques•Slide 54
    • LRRM Experiment 1  SOLT based calibrations show much more noise in line measurement Wafer-Level S-Parameter Calibration Techniques•Slide 55
    • Choosing Calibration Strategy  Understanding of strengths and limitations is essential!  Re-measuring of calibration standards ≠ verification! Method Application SOLT • Well defined conditions • Frequencies < 40GHz SOLR • Rectangular configurations • Double-side probing LRM • Not recommended for wafer-level applications LRM+ • Broadband on-wafer calibration LRRM • Broadband ISS calibration Wafer-Level S-Parameter Calibration Techniques•Slide 56