1. Measurement-Simulation Correlation of High Frequency PCB Interconnects
Pranav Balachander, Anand Ursekar, Dr. Eric Bogatin, Dr. Melinda Piket-May
Department of Electrical, Computer and Energy Engineering
University of Colorado, Boulder

2. Agenda Motivation & Objective Project Outline
Simulation Model & Results
Measurement – Simulation Correlation

3. Motivation & Objective
Problem : Inaccurate values of material properties.
Objective : Establish best practices in simulation tool for good correlation with measurements.
What this means? – Reduced Design Cycle time + No. of board spins  Lower Cost & Time
4.32 mils

4. Project Outline PHASE 1 PHASE 2 PHASE 3 PHASE 4
Model test structure ( Beatty Std.) in HFSS with adjacent return plane
PHASE 2
Perform VNA Measurements from DC to 30 GHz
PHASE 3
Dead Reckoning Simulation vs Measurement
PHASE 4
1. Adjust Dk to match Phase S21.
2. With corrected Dk, adjust Df to match Mag S21.
3. With corrected Df, adjust H to match Mag S11.

5. WRT CMP 28/32 platform
Source: CMP 28/32- Channel Modeling Platforms.
Contains 27 MS/SL structures for systematic validation of 3D - EM solver in freq. & time domains up to GHz.
Test Structure : Series Resonant Beatty Standard.

6. Beatty Standard Simulation Model
Copper Trace
FR408 HR
Constructed by increasing trace width by 3X for a 1” distance at the center.
Materials:
Copper Trace (σ = 5.8 x 107 S/m)
Dielectric : FR408 HR (Dk = 3.67, Df = )

7. Simulation & Measurement Model
HFSS Model
Measured Structure vs
Add Picture of SPARQ Network Analyzer. BS Photo says stripline while we are measuring the microstrip.
Teledyne LeCroy SPARQ Network Analyzer

8. Dead Reckoning vs Measurement
FR408 Manufacturer Specs.
Dk = 3. 67
Df = 0.012
H = 7.4 mils
Measured
Simulated
Phase S11(Deg)
Mag S11(dB)
Mag S21(dB)
Phase S21(Deg)
TDR_Z(ohms)

9. Extraction of Dielectric Constant Dk
Dk = Variable
Df = 0.012
H = 7.4 mils
3.67
Phase S21 matched at Dk = 4.1
3.80
4.00
4.10

10. Extraction of Dissipation Factor Df
Dk = 4.10
Df = Variable
H = 7.4 mils
Mag S21 matched at Df = 0.020

11. Extraction of Dielectric Thickness H
For 3X width,
TDR_Z (Measured) = Ω
TDR_Z(H = 10 mils) = Ω
TDR_Z (default) = Ω
Dk = 4.10
Df = 0.020
H = Variable
TDR Z matched at H = 10 mils

12. Extraction of Dielectric Thickness H
Dk = 4.1
Df = 0.02
H = Variable
Mag S11 matched at H = 10 mils

13. Improvement in Meas. – Sim. Correlation
Initial
Dk = 3.67
Df = 0.012
H = 7.4 mils
Final
Dk = 4.10
Df = 0.020
H 10 mils
Mag S11
Mag S11
Phase S11
Phase S11
Mag S21
Mag S21
Phase S21
Phase S21

14. Conclusion
Cannot rely on manufacturer data to build accurate 3D EM simulations.
Material properties can be extracted using a test structure such as Beatty Standard.
Better Measurement-Simulation Correlation.
Improve ability of simulation to predict measured performance.

15. Acknowledgement
Dr. Eric Bogatin for his guidance and valuable discussions throughout the project duration.
Al Neves and Jim Bell from Wild River Technology for providing the CMP 28/32 board and continued support.
Dr. Melinda Piket-May for valuable suggestions along the way.
CCN Lab for use of testing and measuring equipment.