Production Short Pulse Propagation Systemfor Measuring Frequency Dependent Loss

Introbotics

CorporationCopyright ©

2009

John DiTucci

Introbotics

Corporation

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Objective

•

Measurement Technique

•

Production System Description

Describe a Production System Using the Short Pulse Propagation Measurement Technique

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Measurement Technique

•

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

Short Pulse Propagation (SPP)

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Short Pulse Propagation

TDR Screening

TDT Measurement

Forward and backward TDR on each trace

One pulse measurement on each trace

During processing, a ratio of similar short and long traces removes the effects of the test structure.

If traces similar, proceed to short pulse measurements

Measurements

Impulse Forming Network

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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

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Short Pulse Propagation

Signal ProcessingPropagation Constant Calculation

( ) ( ) ( )( )( )

( ) ( )21

21

2

1

21ln1

llffj

fAfA

ll

fjff

−−

+⎟⎟⎠

⎞⎜⎜⎝

⎛−

−

=+=Γ

φφ

βα

Γ(f)

is the propagation constant.

α(f)

is the attenuation. β(f)) is the phase constant.

l1 and l2 are the lengths of the long and short lines respectively.

A1

(f) and A2

(f) are the magnitude of the Fourier Transforms for the long and short lines respectively.

Φ1

(f) and Φ2

(f) are the phase of the Fourier Transforms for the long and short lines respectively.

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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:

•

Iterate the modeling until there is a good fit with the measured

α

and β.

•

Extract εr

(f), tanδ(f), Z(f)

( ) ( ) ( )( ) ( ) ( )( )ωωωωωωω CjGLjR ++=Γ

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Short Pulse Propagation

Manual SPP In Production Environment

Example SPP production test structure, design data

Actual SPP production test couponsLaunch structure is backdrilled

to increase bandwidth

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Short Pulse Propagation

Supplier 1 Part 1Supplier 1 Part 2Supplier 1 Part 3Supplier 1 Part 4Supplier 1 Part 5Supplier 2 Part 1Supplier 2 Part 2Supplier 2 Part 3Supplier 3 Part 1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 2 4 6 8 10 12 14 16 18 20

Freq, GHz

Atte

nuat

ion,

-dB

/cm

Manual SPP In Production Environment

Attenuation

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Short Pulse Propagation

Relative Transmission Line Performance

Manual SPP In Production Environment

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Manual to Automated

Manual SPP Automated SPP

•

Manual Scope Operation Completely automated scope operation

•

Manual download and storage of data and waveforms

Completely automated download and storage of data and waveforms

•

Extensive user interaction for signal processing

Completely automated signal processing

•

Manual cross sectioning, measuring and modeling

•

Manual cross sectioning, measuring and modeling

•

Manual, assisted probe placement •

Manual, assisted probe placement

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Production SPP Test Flow

Test Specifications

Test Control-

Job Number -

Work Order

Test Setup

Guided Test ConductSingle-Ended

TDRDifferential

TDRSingle-Ended Short Pulse

Differential Short Pulse

Data Storage Waveform StorageStored in database after each test point

Stored on computer hard disk after each test point

Individual test points

All points in Test Specification

Retest Capability

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Production SPP Test Equipment

TDS8000 DSA8200

80E04 TDR Sampling Modules

4-Channel Static Isolation Unit (SIU)

Impulse Forming Network (IFN)

Molex Connector Probes

Computer Running Windows XP

Probing Station

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Production SPP Workstation Model

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Production SPP Workstation Prototype

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Production SPP Test Specification

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Production SPP Test Configuration

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Production SPP Testing

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Production SPP Testing

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Production SPP Testing

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Production SPP Testing

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Production SPP Testing

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Production SPP TDR Waveforms

picoseconds49000 49500 50000 50500 51000

Volts

0.220

0.240

0.260

0.280

0.300

0.320

TDR Waveforms Job J1032_09

LegendLong ForwardShort ForwardLong BackwardShort Backward

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Production SPP TDT Waveforms

picoseconds49400 49600 49800 50000 50200 50400 50600

mill

ivol

ts

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

TDT Pulses Job J1032-09

LegendLong LineShort Line

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Production SPP Acquisition Assessment

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Production SPP Automated Signal Processing

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Summary

Production SPP Measurement System Developed

Completely automated scope operation

Completely automated download and storage of data and waveforms

Completely automated signal processing

Single-ended and Differential