Production Short Pulse Propagation System for Measuring Frequency Dependent Loss. John DiTucci

Production Short Pulse Propagation System for Measuring Frequency Dependent Loss John DiTucci Introbotics Corporation Introbotics Corporation Copyright 2009

Objective Describe a Production System Using the Short Pulse Propagation Measurement Technique Measurement Technique Production System Description 2

Measurement Technique Short Pulse Propagation (SPP) Manual Laboratory process developed by IBM Research in early 90 s Time domain measurements provide frequency dependent Loss: - Attenuation - Phase constant Additional measurements and causal transmission line modeling provide: - Broadband dielectric constant - Broadband loss tangent 3

Short Pulse Propagation TDR Screening Measurements TDT Measurement Impulse Forming Network Forward and backward TDR on each trace If traces similar, proceed to short pulse measurements One pulse measurement on each trace During processing, a ratio of similar short and long traces removes the effects of the test structure. 4

Short Pulse Propagation Signal Processing Preparation for FFT Level Shifting Windowing Time Shifting Zero Padding Fourier Transformation (FFT) Phase information is also obtained from the FFT 5

Short Pulse Propagation Γ Signal Processing Propagation Constant Calculation ( f ) = α( f ) + jβ ( f ) l 1 1 l 2 A ln A 1 2 ( f ) ( ) f + = φ1 j Γ(f) is the propagation constant. ( f ) φ 2( f ) l 1 l α(f) is the attenuation. β(f)) is the phase constant. l 1 and l 2 are the lengths of the long and short lines respectively. A 1 (f) and A 2 (f) are the magnitude of the Fourier Transforms for the long and short lines respectively. Φ 1 (f) and Φ 2 (f) are the phase of the Fourier Transforms for the long and short lines respectively. 2 6

Short Pulse Propagation Cross Sectioning, Measuring, and Modeling Cross section the test vehicle in several places Measure the structures Model the structures Calculate R(f), L(f), C(f), G(f) using a field solver Calculate α and β from: Γ ( ω) = ( R ( ω) + jωl( ω) )( G( ω) + jωc( ω) ) Iterate the modeling until there is a good fit with the measured α and β. Extract ε r (f), tanδ(f), Z(f) 7

Short Pulse Propagation Manual SPP In Production Environment Example SPP production test structure, design data Actual SPP production test coupons Launch structure is backdrilled to increase bandwidth 8

Short Pulse Propagation Manual SPP In Production Environment 0.7 Attenuation 0.6 Attenuation, -db/cm 0.5 0.4 0.3 0.2 Supplier 1 Part 1 Supplier 1 Part 2 Supplier 1 Part 3 Supplier 1 Part 4 Supplier 1 Part 5 Supplier 2 Part 1 Supplier 2 Part 2 Supplier 2 Part 3 Supplier 3 Part 1 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20 Freq, GHz 9

Short Pulse Propagation Manual SPP In Production Environment Relative Transmission Line Performance 10

Manual to Automated Manual SPP Automated SPP Manual, assisted probe placement Manual, assisted probe placement Manual Scope Operation Completely automated scope operation Manual download and storage of data and waveforms Extensive user interaction for signal processing Completely automated download and storage of data and waveforms Completely automated signal processing Manual cross sectioning, measuring and modeling Manual cross sectioning, measuring and modeling 11

Production SPP Test Flow Test Setup Test Specifications Test Control - Job Number - Work Order Guided Test Conduct Single-Ended TDR Differential TDR Single-Ended Short Pulse Differential Short Pulse Data Storage Stored in database after each test point Waveform Storage Stored on computer hard disk after each test point Retest Capability Individual test points All points in Test Specification 12

Production SPP Test Equipment TDS8000 DSA8200 4-Channel Static Isolation Unit (SIU) Impulse Forming Network (IFN) 80E04 TDR Sampling Modules Computer Running Windows XP Probing Station Molex Connector Probes 13

Production SPP Workstation Model 14

Production SPP Workstation Prototype 15

Production SPP Test Specification 16

Production SPP Test Configuration 17

Production SPP Testing 18

Production SPP Testing 19

Production SPP Testing 20

Production SPP Testing 21

Production SPP Testing 22

Production SPP TDR Waveforms 0.320 TDR Waveforms Job J1032_09 Volts 0.300 0.280 Legend Long Forward Short Forward Long Backward Short Backward 0.260 0.240 0.220 49000 49500 50000 50500 51000 picoseconds 23

Production SPP TDT Waveforms 40.0 TDT Pulses Job J1032-09 35.0 30.0 millivolts 25.0 20.0 15.0 Legend Long Line Short Line 10.0 5.0 0.0-5.0 49400 49600 49800 50000 50200 50400 50600 picoseconds 24

Production SPP Acquisition Assessment 25

Production SPP Automated Signal Processing 26

Summary Production SPP Measurement System Developed Single-ended and Differential Completely automated scope operation Completely automated download and storage of data and waveforms Completely automated signal processing 27