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SEMI G80-0200 © SE MI 2000 33 A4.4 Us e of a Loop-Thr o ugh S ampling Head A4-4.1 This is an altern ate approach to measured RMS signal j itter. The in put signal is routed through the loop- through sampling head where i…

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SEMI G80-0200 © SEMI 2000 32
A4-1.4.1 The amount of delay to the input channel must
be greater than the inherent delay of the oscilloscope.
A4-1.5 A high bandwidth-sampling oscilloscope with
statistical calculation capability is recommended. In
addition, when making low jitter measurements high
quality RF connectors and cables will be required. A
setup similar to that shown in Figure A4-2 is adequate
for extracting instrumentation jitter.
A4-1.6 Using semi-rigid coax for the delay will
minimize loss of signal. The pulse generator should be
set to low frequency to maximize the pulse width. A
period of 10MHz with a 50ns pulse width is adequate
for an oscilloscope with an inherent delay of 20ns .
The semi-rigid coax length should be chosen to have a
delay slightly larger than the inherent delay of the
oscilloscope. The proper amount of delay allows
viewing the trigger signal with minimal oscilloscope
horizontal delay.
A4-2 Procedure
A4-2.1 A signal measurement will be made as
indicated in Figure A4-1. The semi-rigid coax (delay)
is not used, but the power splitter output will be
connected to the oscilloscope input. As well, the input
to the power splitter is connected to the signal being
measured. The scope is triggered from the input signal,
and the signal being viewed is delayed from the trigger
by an amount equal to the inherent delay of the
oscilloscope. This measurement step provides a value
referred to here as MEASURED RMS SIGNAL
JITTER, MS.
17
A4-2.2 An instrumentation jitter measurement is then
made as indicated in Figure A4-2. Per this arrangement
the signal being displayed is the same signal that
triggered the oscilloscope. That connection scheme
cannot produce any signal jitter between the trigger and
the signal being viewed; thus any jitter shown on the
oscilloscope display represents instrumentation jitter.
This measurement step provides a value referred to here
as MEASURED RMS INSTRUMENTATION JITTER,
MI.
A4-2.3 Since the signal jitter being measured is
Gausian, the sum of squares relationship is used to
subtract out the instrumentation jitter, and thus obtain
ACTUAL RMS SIGNAL JITTER, AS.
MS = (MI
2
+ AS
2
)
1/2
MS- Measured RMS signal jitter.
MI- Measured RMS instrumentation jitter.
AS- Actual RMS signal jitter.
17 Use of a loop-through sampling head is an alternative method for
making this measurement.
A4-3 Example
A4-3.1 Measured RMS signal jitter MS, the signal
being measured, results in a 10ps measurement.
A4-3.2 Measured RMS instrumentation jitter MI, the
jitter of the measurement setup, results in a 5ps
measurement.
A4-3.3 The actual RMS signal jitter AS is determined
from the relationship:
MS = MI
2
+ AS
2
)
1/2
and calculates to be:
10
2
= 5
2
+ AS
2
100 = 25 + AS
2
75 = AS
2
75
1/2
= AS
8.66ps = AS (actual RMS signal jitter)
Since the jitter is Gaussian, the max value of jitter is
approximately equal to 5 or 6 times the RMS value of
the jitter.
Signal Source
Sampling Oscilloscope
Trigger
Loop through head
In Out
Figure A4-3
Use of a Loop-Through Sampling Head
SEMI G80-0200 © SEMI 200033
A4.4 Use of a Loop-Through Sampling Head
A4-4.1 This is an alternate approach to measured RMS
signal jitter. The input signal is routed through the loop-
through sampling head where it is sampled and sent to
the output of the sampling head. The head output is
connected to the oscilloscope trigger. (See Figure A4-
3.)
A4-4.2 What is Observed When Making MS And MI
Measurements — This dialog is meant to provide
further clarification for making jitter measurements.
This is an example that applies to a jitter measurement
using an oscilloscope with an inherent oscilloscope
delay of 20ns. The signal frequency is 100MHz (period
of 10ns ). The semi-rigid coax delay is set to the
inherent oscilloscope delay of 20ns.
A4-4.3 Measured RMS Signal Jitter, MS — For the
MS measurement the observed edge occurs subsequent
to the edge that triggered the oscilloscope:
N
N
+1
N
+2
N
+2
This pulse triggers the oscilloscope.
Observed Edge –– The pulse that is
displayed on the oscilloscope is not the
same pulse that triggered the oscilloscope.
Trigger:
Signal:
Figure A4-4
Measured RMS Signal Jitter, MS
A4-4.4 The observed edge depends upon the signal
frequency; thus what is displayed is subsequent to the
trigger pulse permitting signal jitter to be observed.
A4-4.5 Measured RMS Instrumentation Jitter, MI —
For the MI measurement the observed edge is the same
edge that triggered the oscilloscope.
N
–1
N
+1
N
+2
N
This pulse triggers the oscilloscope.
Observed Edge –– The pulse that is
displayed on the oscilloscope is the same
pulse that triggered the oscilloscope.
N
–2
Trigger:
Signal:
Figure A4-5
Measured RMS Instrumentation Jitter, MI
A4-4.6 There is no repetitive aspect of the signal, thus
whatever jitter you observe is strictly instrumentation
jitter.
A4-4.7 Summary –– Jitter is only observable for a
periodic signal or repetitive edge. Thus when MS
measurements are made signal jitter is observed
because a subsequent or repetitive signal is displayed
(in addition to instrumentation jitter). When MI
measurements are made the input signal is delayed such
that you see the same edge that trigger the oscilloscope.
That creates a non-repetitive or non-periodic occurrence
of the observed signal, thus the jitter observed is strictly
due to the instrumentation.
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SEMI G81-0703 © SEMI 2000, 2003 1
SEMI G81-0703
SPECIFICATION FOR MAP DATA ITEMS
This specification was technically approved by the Global Automated Test Equipment Committee and is the
direct responsibility of the North American Automated Test Equipment Committee. Current edition approved
by the North American Regional Standards Committee on March 12, 2003. Initially available at
www.semi.org May 2003; to be published July 2003. Originally published October 2000; previously
published March 2003.
1 Purpose
1.1 This document describes the data items that relate
to electronic substrate mapping.
2 Scope
2.1 This document applies only to substrate map data
items.
2.2 This document does not address the transmission,
file naming conventions, storage or archiving of
substrate maps.
2.3 The specification of which data items are optional
and which are required is not specified in this
document.
2.4 The size of each data item described in this
document is maximum size. The actual size may be
further restricted by an application document.
2.5 The order of the data items is not restricted in this
document. The order of the data items may be restricted
by an application document.
NOTICE: This standard does not purport to address
safety issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety and health practices and determine
the applicability of regulatory or other limitations prior
to use.
3 Limitations
3.1 There are no known limitations within the defined
scope.
4 Referenced Standards
4.1 SEMI Standards
SEMI E5 — SEMI Equipment Communications
Standard 2 Message Content (SECS-II)
SEMI T9 — Specification for Marking of Metal Lead-
Frame Strips with a Two-Dimensional Data Matrix
Code Symbol
4.2 IEEE Standards
1
IEEE 754-1985 — IEEE Standard for Binary Floating–
Point Arithmetic
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
5 Terminology
5.1 Definitions
5.1.1 bottom side — the bottom side of the substrate as
defined in the corresponding Appendix (Appendix 1, 2,
or 3).
5.1.2 device — the unit to which the device status code
in the map is assigned including, but not limited to: die,
multi-chip modules and packages.
5.1.3 map — a two-dimensional array of bin codes
derived from electrical test data of a substrate
including, but not limited to: wafer, tray, strip, or tape.
5.1.4 substrate — any carrier of a two-dimensional
array of devices including, but not limited to: wafers,
trays, strips, tape, panels, or boards.
5.1.5 top side — the top side of the substrate as defined
in the corresponding Appendix for that substrate
(Appendix 1, 2, or 3).
6 Requirements
6.1 This document does not define format of each data
item specified in the following chapter. In order to
implement this specification, it requires standardized
and/or specific format definition documents.
Standardized format definition documents are those
generic, application specific or equipment specific
specification, supplied by SEMI. They may be format
specification, static file specification or communication
specification, e.g. SEMI E5. Specific format definition
documents may de defined by supplier and user.
1 Institute of Electrical and Electronics Engineers, IEEE Operations
Center, 445 Hoes Lane, P.O. Box 1331, Piscataway, New Jersey
08855-1331, USA. Telephone: 732.981.0060; Fax: 732.981.1721.
Website www.ieee.org.