Text preview for : 5991-1732EN Specifications Guidelines - White Paper c20140718 [9].pdf part of Agilent 5991-1732EN Specifications Guidelines - White Paper c20140718 [9] Agilent 5991-1732EN Specifications Guidelines - White Paper c20140718 [9].pdf
Back to : 5991-1732EN Specification | Home
Keysight Technologies
Specifications Guidelines
White Paper
Introduction
Keysight Technologies, Inc. has definitions for its Test & Measurement product specifications and how
they are presented. The following material is extracted from these manufacturing recommendations.
Some of the practices may not apply to (Keysight) products introduced before 1996, nor relate directly
to those used in Keysight's worldwide service operations.
Product Specification Terminology
We begin by providing a basis for a common understanding of the language used at Keysight
Technologies when discussing product specifications. Figure 1 depicts the hierarchy of terms.
Product information
Features Specifications Characteristics
Figure 1. Hierarchy of terms
Product Specification Terminology (continued)
Product information is an overall term for any attribute used to describe a
product and its capabilities. It is the most general term used for discussing the
property of a product.
A feature is an attribute of product offered as a special attraction. Features
describe, or enhance, the usefulness of the product to the customer. A feature
is not necessarily measurable; however, it may have an associated measur-
able parameter. If a feature with a measurable parameter is of interest to the
customer, a product specification describes its performance. For example,
HP-IB I/O interface is a feature and it is not measurable but Narrow Resolution
Bandwidth Filter is a feature with the measurable parameter bandwidth.
Specifications formally describe product performance. A specification is a
numerical value, or range of values, that bounds the performance of a product
parameter. The product warranty covers the performance of parameters
described by specifications. Products meet all specifications when shipped from
the factory, or from an Keysight Customer Service Center following calibration.
Environmental specifications bound the external conditions applied to a product
for which the specifications are valid. Some specifications are only valid over a
limited, or restricted, set of external conditions but in such cases the specifica-
tion includes a description of these limited conditions. The environmental speci-
fications also define the conditions that a product may be subjected to without
permanently affecting product performance or causing physical damage. These
can be climatic, electromagnetic (as related to electromagnetic susceptibility),
mechanical, electrical (as related to the power requirements of a product), or
preconditions of operation (e.g., warm-up time or calibration interval).
Characteristics describe product performance that is useful in the application of
the product, but is not covered by the product warranty. They describe perfor-
mance that is typical of the majority of a given product, but is not subject to the
same rigor associated with specifications.
Characteristics are often referred to as Supplemental Characteristics, Typical
or Nominal values but these terms are not formally defined. However, supple-
mental characteristic is a generic term generally referring to all non-warranted
product performance. The terms typical and nominal generally indicate the
expected performance of a given product.
3
Specifications
Specifications describe the performance of parameters covered by the product
warranty. The specifications do not, however, imply that any specific statistical
distribution describes the performance of a parameter. Rather, the specifications
simply bound the quantity of a parameter. This section outlines the model used
to verify that products meet the specifications. The model was presented by
Sherry Read and Timothy Read in the Hewlett-Packard Journal of June 1988, in
their article "Statistical Issues in Setting Product Specifications".
Product margin Guardband
Performance
distribution
Measurement Delta environment Customer
uncertainty and drift guardband
Figure 2. Statistical model for Mean Test line limit Specification
specifications
Figure 2 depicts the statistical model for the specifications. The model repre-
sents the relationship of a measured parameter and the specification. It shows a
single-sided specification but a generalization of the model represents two-sided
specifications that bound both sides of a parameter. Each element of the model
is described.
Guardband is the difference between the test line limit and the value of the
specification. The guardband accounts for measurement uncertainties, changes
in performance due to external conditions, drift and any other mechanism that
may affect performance. The application of guardband ensures, with a high level
of confidence, that a product measured and found to be within the test line limit
will meet the specification.
The test line limit is the pass-or-fail limit used by the manufacturing test proce-
dures. The manufacturing test procedures perform measurements on products
but not all parameters are actually measured. The performance parameter may
be inferred through statistical correlation, sample testing, or other sound means.
Products found to be outside the test line limit undergo repair and re-test.
The performance distribution represents the unit to unit variation of a parameter
measured by a manufacturing test procedure. Production margin is a measure
of the producability of the product. The proximity of the test line limit to the
performance distribution determines the size of the production margin. A small
production margin results in low yields from the manufacturing test procedures.
A larger production margin results in higher yields but a potentially less com-
petitive specification.
4
Specifications (continued)
Delta environmental represents the possible change in performance of a
product over the range of external conditions applied to a product. Typically, the
manufacturing test procedures execute under a limited set of external condi-
tions; usually this is room temperature (25