Lecture 5
Inter-Symbol Interference (ISI)
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI-1
• ideal eye pattern
• eye pattern with noise/jitter reduced noise margin
reduced timing margin
• worst eye pattern with noise/jitter
• reduced noise/timing margin
Î high BER for serial 4 parallel connection
TERA
Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI -2
(i) ISI by reflection from capacitive discontinuity
observation point v
l
l
tf =
v ph
1) For T=2tf
Ideal waveform Waveform by ISI
tj : jitter by ISI
reflected
T
T=2tf
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 3
Ideal waveform Waveform by ISI
T=2tf
T reflected
tj : jitter by ISI
Ideal waveform Waveform by ISI
∆v h
Reduced Noise margin
T=2tf
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 4
Ideal waveform Waveform by ISI
Reduced Noise margin
∆v l
T=2tf
1) For 2T=2tf
2tf
T T
tj : jitter by ISI
TERA
Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 5
Ideal waveform Waveform by ISI
2tf
T T
tj : jitter by ISI
Ideal waveform Waveform by ISI
2tf
T T
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI -6
Ideal waveform Waveform by ISI
∆v h
Reduced Noise margin
2T=2tf
Ideal waveform Waveform by ISI
Reduced Noise margin
∆vl
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI-7
Capacitive reflection
Î+ jitter
Î - jitter Pattern dependent !!
Î power noise -∆v h + delay tf / T dependent
Î gnd noise + ∆vl
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 8
(ii) ISI by reflection from inductive discontinuity
observation point v
l
l
tf =
v ph
1) For T=2tf
Ideal waveform Waveform by ISI
tj : jitter by ISI
reflected
T
T=2tf
TERA
Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 9
Ideal waveform Waveform by ISI
T=2tf
T reflected
tj : jitter by ISI
Ideal waveform Waveform by ISI
T=2tf
TERA
Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI -10
Ideal waveform Waveform by ISI
T=2tf
(iii) power/ground switching noise
1) Charging process
Reduced Noise margin
∆v h
1
∆T =
f0
f 0 => P / G resonance frequency
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 11
Ideal waveform Waveform by ISI
1
∆T =
f0
tj
Jitter by power
Switching noise
P/G Wave propagation
S
signal wave
G
P/G wave
P
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 12
2) Discharging process
1 Reduced Noise margin
∆T =
f0 ∆vl
f 0 => P / G resonance frequency
Ideal waveform Waveform by ISI
1
∆T =
f0
tj
Jitter by ground
Switching noise
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 13
P/G Wave propagation
S
signal wave
G
P/G wave
P
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 14
(iv) Effect of termination (not ISI)
Observation point
1
Z0 Rt > Z0 , Γ L > 0
Ideal waveform Actual waveform
tj
Jitter by termination
mismatch
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 15
2
Observation point
Z0 Rt < Z0 , Γ L < 0
Ideal waveform Actual waveform
tj
Jitter by termination
mismatch
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 16
3 Capacitive load
Observation point
Z0 Rt = Z0
Ideal waveform Actual waveform
tj
Jitter by termination
mismatch
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI - 17
4 L-C termination effect
Observation point
L
Z0 C Rt = Z0
Ideal waveform Actual waveform
tj
1
∆T = = 2π LC Jitter by LC resonance
fr
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
Lecture 5. ISI -18
(v) PCB Line loss
after propagation loss
v( f ) v( f )
f 0 2f0 3f0 ...... f f
f 0 2f0 3f0 ......
more high frequency component
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Terahertz Interconnection and Package Laboratory
Terahertz Interconnection and Package Laboratory
