ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint -...
Transcript of ECE 497 JS Lecture -07jsa.ece.illinois.edu/ece497js/Lect_08.pdfTitle Microsoft PowerPoint -...
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]
2Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
2
2 2
1111 22( X )S = S =
XΓ
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−=
3Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
2
2 2
1111 22( X )S = S =
XΓ
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−
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
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
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
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
8Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
0.05
0.1
0.15
0.2
0.25
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0.35
0.4
0.45
0.05
0.1
0.15
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0.25
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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
9Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
0
0.1
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0.5
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0
0.1
0.2
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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
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
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
12Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
With parasiticsNo parasitics
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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
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
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
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
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
18Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
REFLECT
connect reflect
Step 3 - REFLECT Calibration
A B
Ra Rb
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
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
21Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
Probes & Probe Stations
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
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
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
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
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
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
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
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
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
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
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
33Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
Eye Diagram
34Copyright © by Jose E. Schutt-Aine , All Rights ReservedECE 497-JS, Spring 2004
Pseudorandomsequencegenerator
Transmitter Receiver
Scope
Trig Vert
Clk
Data
FiberEye Pattern Analysis