This document provides an overview of signal integrity (SI) and discusses various SI topics including transmission line theory, time domain analysis, frequency domain analysis, equalization techniques, and high speed interfaces. It begins with defining SI and its importance. It then covers transmission line theory concepts such as lossy and lossless lines, single-ended and differential signaling. The document discusses time domain analysis methods like eye patterns, jitter, setup/hold times and rise/fall times. Frequency domain analysis methods such as S-parameters, insertion loss, return loss, and crosstalk are also outlined. Finally, it briefly introduces some common high speed interfaces including DDR, SAS, SATA, USB, and PCIe.

1. Signal Integrity
By Asif

2. Outline
 Overview of SI
 Transmission Line Theory
 Time Domain Analysis
 Frequency Domain Analysis
 Equalization Techniques
 High Speed interfaces
 3D Modeling

3. Overview
 Signal integrity is an important activity at all levels of
electronics packaging and assembly, from internal
connections of an integrated circuit (IC),through
the package, the printed circuit board (PCB),
the backplane.
 SI is a set of measures of the quality of an electrical
signal.
 That ensures all signals transmitted are received
correctly.
 That ensures signals don’t interfere with one another.
 That ensures signal don’t damage any device.

4. Transmission line Theory
 Introduction
 Lossy Transmission Line
 Lossless Transmission Line
 Single Ended Signaling
 Differential Signaling
 Tightly Coupled & Loosely Coupled

5. Introduction
 The transfer of energy from one point to another takes
through either wave guides or transmission lines.
 In an electronic system, the delivery of power
requires the connection of two wires between the
source and the load. At low frequencies, power is
considered to be delivered to the load through the
wire.
 In the microwave frequency region, power is
considered to be in electric and magnetic fields that
are guided from lace to place by some physical
structure. Any physical structure that will guide an
electromagnetic wave place to place is called a
Transmission Line.

6. Lossy Transmission Line
 Impedance of lossy Transmission line is,
Where R-series resistor of the conductor
L-due to the magnetic fields self inductance
C-shunt capacitor between two conductor
G-shunt resistor between signal wire and the return wire
Z0-charecteristic impedance

7. Lossless Transmission Line
 Impedance of lossless Transmission line is,
 When the R and G are negligibly small the
transmission line,the model depends only on the L
and C elements

8. Single Ended Signaling
 A single-ended measurement is taken as the voltage
difference between a wire and ground.
 The noise is only on the positive wire, and as a
result, it is still measured along with the output
voltage from the sensor
 Single-ended signaling is the simplest and most
commonly used method of transmitting electrical
signals over wires.
 One wire carries a varying volt that represents the
signal, while the other wire is connected to a
reference voltage, usually gnd.

9. Differential Signaling
 Differential signal is a method of transmitting
electrically with two complementary signal sent on
two pared wires called differential pair
 It is Suitability for use with low-voltage electronic
signals.
 It will resist the EM interferences.
 The main benefit of a differential measurement is
noise rejection

10. Tight coupling &Loosely coupled
 Tight coupling is usually reduces flexibility and re-usability A Tightly
Coupled Object is an object that needs to know quite a bit about
other objects and are usually highly dependent on each other's
interfaces.
 Loosely coupled to reduce the inter-dependencies between
components of a system Loose coupling is a much more generic
concept intended to increase the flexibility of a system

11. Difference between Time& Frequency
Domain Analysis
 Time domain analysis examines the amplitude vs
time characteristics of a measuring signal
 Time domain analysis gives the behavior of the
signal over time
 Frequency domain analysis replaces the measured
signal with a group of sinusoids which, when added
together, produce the waveform equivalent to
original
 The relative amplitudes, frequency, phases of the
sine waves are examined
 Frequency domain analysis is much easier, some
equations are can’t be solved while time domain they
can be solve easily in frequency domain

12. Difference between Time& Frequency Domain
Analysis

13. Time Domain Analysis
 Introduction
 Eye pattern
 Jitter
 Setup/Hold Time
 Rise Time/Fall Time

14. Introduction
 A graphical representation of the change of some
value with respect to time
 In the time domain, the signal or function's value is
known for all real numbers, for the case
of continuous time, or at various separate instants in
the case of discrete time
 A time-domain graph shows how a signal changes
with time, whereas a frequency-domain graph shows
how much of the signal lies within each given
frequency band over a range of frequencies.

15. Eye Pattern
 Evoluation of combined effect of channel noise and Intersymbol
interference(ISI).
 Open eye pattern corresponds to minimum signal distortion.

16. Jitter
• Jitter is the deviation from true periodicity of a presumed
periodic signal in electronics.
• Jitter period is the interval between two times of
maximum effect (or Minimum effect) of a signal that
varies with time.
1.Ranfom Jitter(gaussian Jitter)
• Is unpredictable electronic noise
• Random jitter typically follows a gaussian distribution or
normal distribution
• Caused by thermal noise and another reason for jitter to
have a distribution or normal distribition

17. Jitter(Cont…)
2.Deterministric Jitter
 It is a type of clock timing jitter or data signal jitter is
predictable and reproducible
 The peak to peak value of this jitter is bounded and
the bounds can easily be observed and predicted
Total jitter
 Total jitter (T) is the combination of random jitter (R)
and
deterministic jitter (D)
 T = Dpeak-to-peak + 2× n×Rrms,
 in which the value of n is based on the bit error rate
(BER) required of the link

18. Setup Time
 Setup time is the minimum amount of time the data signal should be
held steady before the clock event , so that the data are reliably
sampled by the clock.This applies to synchronous circuit such as flip
flop.
 The time when input is available and stable before the clock pulse is
applied is called setup time.
Hold Time
 Hold time is the minimum amount of time the data signal should be
held steady after the clock event, so that the data are rapidly
sampled.
 The time after clock pulse where data input is held stable is called
hold time.

19. Rise Time/Fall Time
Rise Time(TR)
 Amount of time it takes the output voltage to go from 10%
of the Logic "1" level to 90% of the Logic "1" level..
Measured in nS.
Fall Time(TF)
 The time required for the output voltage to go from 90%
of the Logic "1" level to 10% of the Logic "1" level..
Measured in nS.

20. Frequency Domain Analysis
 Introduction
 S-Parameter
 Insertion Loss
 Return Loss
 Cross Talk
 Nyquist Frequency
 Knee Frequency
 Skew

21. Introduction
 The frequency response of a system is defined
steady state response of the system
 A graphical representation of the amount of energy
present in a signal at each of many frequencies
 The frequency response of a system is defined
steady state response of the system
 The frequency domain values are really just a series
of sinusoidal equivalents, so amplitudes are usually
represented the same as in the time domain.
 The frequency domain is usually derived by
computing a Fast Fourier Transform (FFT) of a time
domain signal.

22. S-Parameter
 S-Scattering parameters which describe electrical behavior of
transmission line signals.
 The following information must be defined when specifying a set of
S-parameters:
• The Frequency(f)
• Characteristic impedance (Z0)
• Number of Ports
 Use it as a simplified passive interconnect model that
– simulates faster,
– is easier to correlate with actual hardware, and
– can be offered to the industry while protecting IP

23. S-Parameter(cont…)
 A behavioral representation (model) of passive
interconnect

24. Insertion Loss
 The loss of signal power resulting from the insertion
of a device in a transmission line
 Is usually expressed in db
PT is power transmitted
PR is power received

25. Return Loss
 The loss of power in the signal returned/ reflected by
a transmission line
 This discontinuity can be terminating load or with a
device Inserted in the line
Pi incident power
Pr reflected power

26. Cross Talk(XT)
 crosstalk (XT) is any phenomenon by which
a signal transmitted on one circuit or channel of
a transmission system creates an undesired
effect in another circuit or channel.

27. Crosstalk (cont….)
 Cross Talk occurs on PCB and twisted wire cable

28. Crosstalk (cont….)
Near end crosstalk(NEXT)
 NEXT is a measure of the ability of the cabling to reject crosstalk
 The signals traveling through adjacent pairs of wire in twisted pair
cabling interfere with each other
 Interference between two pairs in a cable is measured at the same
as the interfering transmitter
Power Sum Near end Crosstalk(PSNEXT)
 A NEXT measurement which includes the sum of crosstalk
contribution of all adjacent pairs
Far end Crosstalk(FEXT)
 Interference between two pairs of a cable measured at the other end
of the cable with respect to Interfering transmitter

29. Crosstalk (cont….)
Equal Level Far end Crosstalk(ELEFEXT)
 An FEXT measured with attenuation compensation.
Power Sum Far end Crosstalk(PSFEXT)
 It is the sum of all interference signals, which are
coupled in a pair of conductors.

30. Nyquist Rate
 Minimum sampling rate required to prevent alaiasing
 Defines the maximum sampling rate given a fixed
maximum frequency
 The maximum frequency that won’t be alaised, is “half”
the given sampling rate.
fs≥2fc
Fs- Sampling Frequency fc- Highest Frequency

31. Nyquist Rate(cont…)
Alaiasing
 The sampling points are correct but produce a
completely different wave

32. Knee Frequency
 Knee frequency is an estimate of the highest frequency
content of the signal
 If the Rise Time is smaller the highest frequency content
will have higher frequency
 If ‘t’ denotes the 10% to 90% rise time of a signal,then an
estimate for the highest frequency content of the
signal(or)Knee Frequency given by
fmax Highest Frequency content

33. Skew
 Skew is the time delta between the actual and expected arrival time
of a clock signal.
 The time delay difference between two or more signal path is called
skew
 It can be intrinsic or Extrinsic
Intrinsic: Propagation delay between the device outputs.
Extrinsic:Due to unbalanced trace lenghts (or) output loading.

34. High Speed Interfaces
 DDR(Double Data Rate)
 SAS(Serial Attached SCSI)
 SATA(Serial Advanced Technology Attachment)
 USB(Universal Serial Bus)
 PCIE(Peripheral Component Interconnect Express)

35. DDR(Double Data Rate)
 DDR SDRAM is a class of memory integrated circuits used
in computers.
 DDR SDRAM, also called DDR1 SDRAM, has been
superseded by DDR2 SDRAM and DDR3 SDRAM.
 Compared to single data rate (SDR) SDRAM, the DDR
SDRAM interface makes higher transfer rates possible by
more strict control of the timing of the electrical data and
clock signals.
 DDR SDRAM with a certain clock frequency achieves nearly
twice the bandwidth of a SDR SDRAM running at the same
clock frequency.
 DDR SDRAM gives a transfer rate of (memory bus clock
rate) × 2 (for dual rate) × 64 (number of bits transferred) / 8
(number of bits/byte). Thus, with a bus frequency of
100 MHz, DDR SDRAM gives a maximum transfer rate of
1600 MB/s.

36. DDR(cont…)
 VERSIONS
• SDRAM-66 MHz,100 MHz,133 MHz
• DDR1-266,333,400 MHz
• DDR2-400,533,677,800 MHz
• DDR3-460,533,677,800,933,1066 MHz
• DDR4-1600 to 3200 MHz

37. LRDIMM
 DIMM-Dual Inline Memory Module, comprises a series of
dynamic random-access memory integrated circuits
 LRDIMM-Load Reduced DIMM,this technology uses
distributed buffer approach to accomplish memory
bandwidth efficiency
 Improve LRDIMM architecture for better SI or data
signals
 That support higher densities than RDIMM and contain
memory buffer
 LRDIMM uses in memory intensive application in data
centers ,could computing and high performance
computing(HPC) environments

38. RDIMM
 RDIMM-Registered Dual In line Memory Module
 This is in constrast to the unbuffered data approach used
with DDR4
 DDR4 LRDIMM’s shorter trace length and quicker
buffering scheme make the overall latency and bus
read/write turnaround time compared to DDR4 RDIMM

39. UDIMM
 UDIMM-Unbuffered/Unregistered DIMM
 When compared to registered
memory(RDIMM),conventional memory is usually
referred as UDIMM
 Most commonly in PC and Laptops
 It’s faster than the RDIMM and low cost. But are not
stable as RDIMM

40. SAS(Serial Attached SCSI)
 SCSI-Small Computer System Interface
 When it was introduce the speed of SAS is 3Gbps,Then In 2009 the
speed of SAS is 6Gbps,In 2013 speed is increased to 12Gbps
 It is point to point serial protocol that moves data to and from
computer storage devices
 Types of component,
• Initiator-Request for processing by a target devices
• Target-Contains logical units and target ports
• Service Delivery Subsystem-I/O system transmit initiator to
target and vice versa
• Expanders-Communicate between multiple SAS devices to
initiator port

41. SATA(Serial Advanced Technology
Attachment)
 SATA is the next generation storage interface for
PCs and low-end Servers.
 SATA is highly viable for servers and storage
networks
 One SATA controller can aggregate multiple ports
 Multiple SATA drives can be linked using backplanes
and external enclosures
 SATA was designed to provide excellent speed and
storage at a low cost
 Cost and scalability provides potential for greater
storage capacity at a lower cost than networked or
server storage

42. SATA(cont…)
 SATA revision 1.0 - 1.5 Gbit/s - 150 MB/s
 SATA revision 2.0 - 3 Gbit/s - 300 MB/s
 SATA revision 3.0 - 6 Gbit/s - 600 MB/s
 SATA revision 3.1
 SATA revision 3.2 - 16 Gbit/s - 1969 MB/s

43. PCIe(Peripheral Component Interconnect
Express)
 PCIe is a high speed serial computer expansion bus.
 A computer bus is used to transfer data from one location
or device on the motherboard to the central processing
unit where all calculations take place.
 PCIe has been a versatile ,function way to sonnect
sound,video and network card to a mother board.
 Two different parts of a Bus
 Address bus-transfers information about where the
data should go
 Data bus-transfers the actual data

44. PCIe(cont…)
Plug&Play(PnP)
 Automatically recognized and configured to work on
the system.

45. PCIe(cont…)
 Every device has its own dedicated connection,so
devices no longer share bandwidth like they do on a
normal bus.
 PCI Express link performance

46. USB
 USB-Universal Serial Bus
 Nowadays most of the electronic devices are connected by the USB
 USB needs to operate at maximum voltage of 5.00 V and maximum
current of 500-900 mA
 USB has can connect maximum number of devices around 127
 It is a 4 pin connector
• Pin 1-Vcc(+5V)
• Pin 2-(D-)
• Pin 3-(D+)
• Pin 4-Gnd

47. USB(Cont…)
 VERSIONS,
• USB 0.7 – released in November 1994
• USB 0.8 – released in December 1994
• USB 0.9 – released in April 1995
• USB 0.99 – released in August 1995
• USB 1.0 - Release Candidate – released in November 1995
• USB 1.x -12 Mbps
• USB 2.0 -480 Mbps
• USB 3.0 -3.2 Gbps
• USB 3.1 -10 Gbps

48. Equalization Techniques
 Emphasis
 FFT
 IFFT
 FFE
 DFE
 CTLE
 FIR
 FFE

49. Emphasis
 Emphasis is the intentional alteration of the amplitude-vs
-frequency characteristics of the signal to reduce the
effects of noise in a communication
Pre-emphasis:
 Pre-emphasis refers to boosting the relative amplitudes
of the modulating voltage for higher audio frequencies
from 2 to approximately 15 KHz.
 Which boosting the relative amplitudes for high frequency
to improve the overall signal to noise ratio and the mirror
operation is called de-emphasis
 pre-emphasis is done at the transmitter

50. Emphasis(cont…)
De-emphasis:
 De-emphasis is the complement of pre-emphasis.
 De-emphasis means attenuating those frequencies by the amount by
which they are boosted.
 de-emphasis is done in the receiver.
 The whole system of pre-emphasis and de-emphasis is called
emphasis

51. FFT
 Fast Fourier Transform (FFT) is to compute
the discrete Fourier transform (DFT) and its
inverse. Fourier analysis converts time (or space) to
frequency and vice versa
 The DFT is most important in the area of frequency
(spectrum) analysis because it takes a discrete signal in
the time domain and transforms that signal into its
discrete frequency domain representation
 The most important difference is that an FFT is much
faster than DFT
 FFT algorithms are also much more accurate than
evaluating the DFT

52. IFFT
 The Fourier transform is used to convert the signals
from time domain to frequency domain and the
Inverse Fourier transform(IFFT) is used to convert
the signal back from the frequency domain to the
time domain
 FFT which is a technique to analyse signal in
frequency domain. If signal is in time domain and are
not able to find problem then we can take FFT of this
signal and find out how many frequency components
are present and analyse it better
 if we convert it back to time domain then all
frequency will be available but it will be difficult as
which frequency was present at what time, so one
can replace IFFT and FFT

53. FFE
 Feed-Forward Equalization (FFE) is an equalization
technique that corrects the received waveform with
information about the waveform itself and not information
about the logical decisions made on the waveform
 FFE basically acts like a FIR (finite impulse response)
filter and uses the voltage levels of the received
waveform associated with previous and current bits to
correct the voltage level of the current bit
 FFE is only concerned with correcting voltage levels in
the waveform
 The mathematical expression of FFE is,
e(t) = c0r(t - (0TD)) + c1r(t - (1TD)) + c2r(t - (2TD))

54. DFE
 Decision Feedback Equalization (DFE), DFE
calculates a correction value that is added to the
logical decision threshold
 The mathematical expression of FFE is,
V(k) = c1s(k - 1) + c2(k - 2)
 DFE and FFE are different equalization techniques,
it is not uncommon to use both at the receiver
 DFE and FFE are both useful equalization
techniques that can be used to open closed eyes at
the receiver

55. CTLE
 CTLE- Continous Time Linear Equalization
 In the transmitter, equalization using a CTLE is
implemented to provide pre-emphasis of the high
frequency leading edge of bit transitions
 This can be done in two techniques are,
1) CTLE using high pass filter (HPF) with poles and
zeros
• A HPF CTLE can provide emphasis in its high
frequency response and can be created using a
single pole and zero, H(s) = K*(s-z)/(s-p)
2)CTLE using a feed-forward equalizer (FFE)
• A FFE CTLE can provide emphasis in its high
frequency response and be created using
delays,gains and summer

56. FIR
 Finite impulse response (FIR) filter is
a filter whose impulse response (or response to any
finite length input) is of finite duration, because it
settles to zero in finite time
 This is in contrast to infinite impulse response (IIR)
filters, which may have internal feedback and may
continue to respond indefinitely
 For a discrete-time FIR filter of order N,

57. 3D Modeling
 Introduction
 MOM-Method Of Moments(2D)
 Quasi Static Modeling(2.5D)
 FEM-Finite Element Modeling(3D)
 FDTD-Finite Difference Time Domain(3D)

58. Introduction
 Advantages of Simulation Modeling are,
• Optimize the geometry for strength and weight
• Select materials that meet weight, strength, and budget
requirements
• Simulate part failure and identify the loading conditions
that cause them

59. MOM
 MOM-Method Of Moments
 Analyzing PCB with respect to radiated emission and
radiated susceptibility in the frequency domain
 Can be used for analyzing any planar structure
 EMC applications-Electro magnetic
compatability,shall not generate EM disturbance

60. Quasi Static Modeling(2.5D)
 FDTD-Finite Difference Time Domain Method
 Numerical Analysis technique
 FDTD can cover wide range frequency with a signal
simulation
 It will used in a non linear material property
 FDTD uses the E and H fields directly. Since most
EMI/EMC modelling applications are interested in
the E and H fields

61. FEM
 FEM-Finite Element Modelling
 It is a numerical technique for finding approximate
solutions to boundary value problems for partial
differential equations
 It uses subdivision of a whole problem domain into
simpler parts, called finite elements
 from the calculations of variations to solve the
problem by minimizing an associated error function
 It will solve electro magnetic field(TE,TM,TEM)

62. FDTD
 FDTD-Finite Difference Time Domain Method
 Numerical Analysis technique
 FDTD can cover wide range frequency with a signal
simulation
 It will used in a non linear material property
 FDTD uses the E and H fields directly. Since most
EMI/EMC modelling applications are interested in
the E and H fields

63. DESIGN OF EXPERIMENTS
 It is a design of any information gathering exercise
where variation is present
 These statics used for controlled experiments
 Advantages of DOE,
• Reliability is increased
• Shorter development time
• Process performing normal
• Cost is less
• Reduction of process variation

64. GENETIC ALGORITHM
 Genetic algorithm(GA) is a heuristic that mimics the
process of natural selection
 Heuristic is designed for solving problem more
quickly
 GA which generates solution to optimization problem
using techniques inspired by natural evolution

65. ARTIFICIAL NEURAL NETWORK(ANN)
 An Artificial Neural Network (ANN), usually called neural
network (NN), is a mathematical model or computational
model that is inspired by the structure and/or functional
aspects of biological neural networks
 A neural network consists of an interconnected group
of artificial neurons, and it processes information using
a connectionist approach to computation

66. HFSS-High Frequency Structural Simulator
Solution Types:
Driven Modal: Use this type of solution for passive high frequency
structures such as microstrips, waveguides, and transmission lines.
Driven Terminal: Use this type for simulations that deal with
signal integrity for models that have multi-conductor transmission lines.
Eigenmode: Use this type to calculate resonances of a given
structure(e.g. filters).
Transient: Use this type to employ time-domain solutions for
simulations with pulsed excitations such as ultra-wide band antennas.