ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint -...

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1 Copyright © by Jose E. Schutt-Aine , All Rights Reserved ECE 497-JS, Spring 2004 ECE 497 JS Lecture -07 Measurements Spring 2004 Jose E. Schutt-Aine Electrical & Computer Engineering University of Illinois [email protected]

Transcript of ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint -...

Page 1: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

1Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

ECE 497 JS Lecture -07Measurements

Spring 2004

Jose E. Schutt-AineElectrical & Computer Engineering

University of [email protected]

Page 2: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

2Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

2

2 2

1111 22( X )S = S =

Γ−−

2

2 2

1112 21( )XS = S =

XΓΓ

−−

c ref

c ref

Z ZZ Z

Γ−

=+

( )( )R j L G j Cγ ω ω= + +

cR j LZG j C

ωω

+=

+

S-Parameters of TL

lX e γ−=

Page 3: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

3Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

2

2 2

1111 22( X )S = S =

Γ−−

2

2 2

1112 21( )XS = S =

XΓΓ

−−

c ref

c ref

Z ZZ Z

Γ−

=+

LCβ ω=

cLZC

=

S-Parameters of Lossless TL

j lX e β−=

If Zc = Zref

011 22S = S = j l

12 21S = S = e β−

Page 4: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

4Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

• Calibrate Network Analyzer– Obtain calibration standards– Determine frequency range for testing– 8-term, 12-term, TRL, SOLT

• Perform Measurements– Account for connectors if any– Probe station

• Process Data– Convert to other network parameters– Time-domain option

Network Analyzer Measurements

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5Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Example – Characterization of DIP Packages

View of DIP Lead Frame

DIP Mounted on PCB with SMA

connectorcenter

pin PCboard

microwaveconnector

pin

CROSSSECTION

package

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6Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

• Devise Model for Package + Environment– Obtain accurate model for topology– Determine frequency range for model

• Calibrate ANA and Perform Measurements– De-embed connector or use TRL– S Parameters can be converted

• Optimize Model using Simulator– ADS or SPICE– Select accurate optimization scheme

Package Characterization Procedure

Page 7: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

7Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

1

4

3

2

5

11

9

10

7

8

6

12 13

15

16

17

18

19

20

14

23

21

22

24

C1-24

C23-24C1-2

C22-23C2-3

C3-4

C4-5

C21-22

C20-21

C19-20

C18-19

C8-9

C17-18

C16-17

C12-13

C15-16

C14-15

C13-14

C7-8

C5-6

C6-7

C11-12

C10-11

C9-10

Example – Topology & Model

Circuit model for 2-port measurement Between 2 pins

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8Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.1 0.3 0.5 0.7 0.9Frequency (GHz)

S11 for L = 5.2 nHModel Measured

-80

-60

-40

-20

0

20

40

60

80

-80

-60

-40

-20

0

20

40

60

80

0.1 0.3 0.5 0.7 0.9Frequency (GHz)

S11 for L = 5.2 nH

Model Measured

0.8

0.85

0.9

0.95

1

0.8

0.85

0.9

0.95

1

0.1 0.325 0.55 0.775 1Frequency (GHz)

S21 for L = 5.2 nH

Model Measured

-180

-135

-90

-45

0

-180

-135

-90

-45

0

0.1 0.3 0.5 0.7 0.9Frequency (GHz)

S21 for L = 5.2 nH

Model Measured

Model and Measured scattering parameters for pins 12-13 for the case were model inductance is assumed to be 5.2 nH.

DIP Example – S-Parameters

Page 9: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

9Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

0

0.1

0.2

0.3

0.4

0.5

0.6

0

0.1

0.2

0.3

0.4

0.5

0.6

0.1 0.3 0.5 0.7 0.9Frequency (GHz)

S11 for Inductance X 2

Model Mesured

-150

-100

-50

0

50

100

-150

-100

-50

0

50

100

0.1 0.3 0.5 0.7 0.9Frequency (GHz)

S11 for Inductance X 2

Model Measured

0.75

0.8

0.85

0.9

0.95

1

0.75

0.8

0.85

0.9

0.95

1

0.1 0.325 0.55 0.775 1Frequency (GHz)

S21 for Inductance X 2

Model Measured

-180

-90

0

90

180

-180

-90

0

90

180

0.1 0.3 0.5 0.7 0.9

Phas

e (d

egre

es)

Frequency (GHz)

S21 for Inductance X 2

Model Measured

Model and Measured scattering parameters for pins 12-13 for the case were model inductance is assumed to be 10.4 nH.

DIP Example – Inductance

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10Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Board with traces

L-shaped support

Center pin

screw

Flange-mountconnector

Coaxial-Microstrip Transition

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11Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

L1CL1 CR2

L2CL2 CR1

TL1SMA SMA

In Out

Coaxial-Microstrip Transition

TDR Plot

Equivalent Circuit

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12Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

With parasiticsNo parasitics

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13Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

DUT

microstrip microstrip

coaxial connector coaxial connector

TRL CALIBRATION SCHEME

Want to measure DUT only and need to remove the effect of coax-to-microstrip transitions. Use TRL calibration

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14Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Error BoxA

Error BoxB

Port1

Port2Γ1 Γ2

1 2

W1 W2Measurement

Planes

Error boxes A and B account for the transition parasitics and the electrical lengths of the microstrip.

Make three standards: Thru, Line and Reflect

A model for the different error boxes can be implemented

TRL Error Box Modeling

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15Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Using T parameters (transfer parameters), we can show that if

1 11 2

1 22 221

11

b S ba S aS

−∆ = −

1 11 1 12 2b S a S a= +2 21 1 22 2b S a S a= +

12 21 11 22S S S S∆ = −

11 2

22 221

11

S bR

S aS−∆

= −

Use T Parameters

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16Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

connect thru

A B

Ra Rb

Rt

t a bR R R=

Step 1 - THRU Calibration

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17Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

LINE

connect line (Note: difference in length between thru and line)

A B

Ra Rb

Rd

LINE

RL

Step 2 - LINE Calibration

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18Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

REFLECT

connect reflect

Step 3 - REFLECT Calibration

A B

Ra Rb

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19Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

-5

0

5

1 1.5 2 2.5 3 3.5 4 4.5 5

Measured |S11| of Microstrip Unknown Relative to TOUCHSTONE Models

PORT EXT. calibrationTRL calibration

Rel

ativ

e M

agni

tude

, dB

Frequency, GHz

PORT EXT. data compared to L=.808 nH modelTRL data compared to L=.948 nH model

TRL – Measurement Comparison

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20Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

-20

-15

-10

-5

0

1 1.5 2 2.5 3 3.5 4 4.5 5

Measured Data for Microstrip Unknown

with TRL calibrationwith 722 ps port ext. (inc. barrel)

|S11

| (d

B)

Frequency, GHz

Measured 10/18/94

TRL – Measurement Comparison

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21Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Probes & Probe Stations

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22Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

H(ω)

Goal: Simulate the time-domain response of a network using frequency-domain measurements.

Motivation: Fast rise time pulse and steps are difficult to design; but high-frequency signals are available

Using Frequency Domain Data forTime-Domain Simulation

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23Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

One-Portb1(ω)

a1(ω)

Scattering parameter of one-port network can be measured over a wide frequency range. Since incident and reflected voltagewaves are related through the measured scattering parameters, the total voltage can be determined as a function of frequency.

Using Frequency Domain Data forTime-Domain Simulation

Approach

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24Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

( )( 0, )2

sf

VV x ωω= =

11( )( 0, ) ( )2

sb

VV x Sωω ω= =

[ ]11( )( 0, ) 1 ( ) ( )2

so

VV x S Vωω ω ω= = + =

Unknown andJunction

Discontinuities

Zo

Zo

Reference Line

Vf

x=0

Vb

Vs(ω)

One-Port S-Parameter Measurements

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25Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

2( ) ( ) j fts sV v t e dtπω

∞ −

−∞= ∫

[ ] 211( ) ( ) 1 ( ) j ft

o sv t V S e dtπω ω∞ +

−∞= +∫

S11(ω) is measured experimentally. Assume vs(t) to be an arbitrarytime-domain signal (unit step, pulse, impulse). Vs(ω) is its transform

Since the system is linear, its response in the time domain is the superposition of the responses due to all frequencies

Frequency-to-Time Analysis

Page 26: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

26Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

• Measure S11(f)

• Calculate Vs(ω) analytically

• Evaluate Vo(ω)= [1+S11(ω)] .

• Feed Vo(ω) into inverse Fourier transform to get vo(t)

Transformation Steps

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27Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

• Discretization: (not a continuous spectrum)

• Truncation: frequency range is band limited

F: frequency rangeN: number of points∆f = F/N: frequency step∆t = time step

Problems and Issues

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28Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

1. For negative frequencies use conjugate relation V(-ω)= V*(ω)

2. DC value: use lower frequency measurement

3. Rise time is determined by frequency range or bandwidth

4. Time step is determined by frequency range

5. Duration of simulation is determined by frequency step

Addressing Frequency and Time Limitations

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29Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Problems & Limitations(in frequency domain)

Discretization

Truncation in Frequency

No negativefrequency values

No DC value

Consequences(in time domain)

Solution

Time-domain response will repeat itself periodically (Fourier series) Aliasing effects

Take small frequency steps. Minimum sampling rate must be the Nyquist rate

Time-domain response will have finite time resolution (Gibbs effect)

Take maximum frequency as high as possible

Time-domain response will be complex

Define negative-frequency values and use V(-f)=V*(f) which forces v(t) to be real

Offset in time-domain response, ringing in base line

Use measurement at the lowest frequency as the DC value

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30Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

0 1 2 3-0.5

0.0

0.5

1.0

1.5Simulated Step Response

Time (ns)

Ref

lect

ion

Coe

ffic

ient

Microstrip Line TDR Simulation

Page 31: ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint - Lect_08.ppt Author Jose Schutt-Aine Created Date 2/11/2004 8:52:34 PM

31Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Jitter is difference in time of when somethingwas ideally to occur and when it actually did occur.

Some devices specify the amount of marginal jitter and totaljitter that it can take to operate correctly. If the cable addsmore jitter than the receiver’s allowed marginal jitter and total jitter the signal will not be received correctly. In this case the jitter is measured as in the below diagram

Jitter Definition

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32Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Eye Diagrams

• Eye diagrams are a time domain display of digital data triggered on a particular cycle of the clock. Each period is repeated and superimposed. Each possible bit sequence should be generated so that a complete eye diagram can be made

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33Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Eye Diagram

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34Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004

Pseudorandomsequencegenerator

Transmitter Receiver

Scope

Trig Vert

Clk

Data

FiberEye Pattern Analysis