Page 137 - Electrical Engineering Dictionary

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short-distance personal or business commu- tion and conduction cutoff. In a class A am-
nication. pliﬁer, as the amplitude of an applied sinu-
soidal signal is increased, the output will start
city-block distance a distance measure to clip at both ends simultaneously. This is
between two real valued vectors (x 1 ,x 2 ,..., equivalent to a conduction angle of 360 de-
x n ) and (y 1 ,y 2 ,..., y n ) deﬁned as grees as long as the output signal is not clip-
ping, which is avoided. This term is often
n
X
used to include any ampliﬁer operating with
D city block = |x i − y i |
signallevelslowenoughsuchthatsignalclip-
i=1
ping is not present (i.e., small signal condi-
City-block distance is a special case of
tions).
Minkowski distance when λ = 1. See also
Minkowski distance. Also called Manhat-
class A-B ampliﬁer most current source
tan distance.
ampliﬁers fall into this category, which in-
cludes all ampliﬁers biased somewhere be-
cladding the optical material that concen-
tween class A and class B. As the amplitude
trically surrounds the ﬁber core and provides
of a sinusoidal signal is increased, the output
optical insulation and protection for the core.
will start to cut off ﬁrst. Further increases
The refractive index of the cladding must be
will cause clipping due to saturation. Thus
lower than that of the core material so that
the conduction angle is between 180 and 360
optical power is guided through the ﬁber by
degrees, dependent on applied signal ampli-
total internal reﬂection at the core-cladding
tude. Device saturation is usually avoided.
boundary. See also total internal reﬂection,
Snell’s Law.
class B ampliﬁer an ampliﬁer in which
the active device acts as a modulated cur-
clamping the process of ﬁxing either the
rent source biased at conduction cutoff. In
minima or maxima of a voltage.
a class B ampliﬁer, an applied sinusoidal sig-
Clapp oscillator an oscillator whose fre- nal will result in only half of the sinusoid
quency is determined by a tuned parallel LC being ampliﬁed, while the remaining half is
circuitwithasplitcapacitance, i.e., twoseries cut off. Further increases in the signal am-
capacitances, in the capacitive branch and an plitude will eventually cause the remaining
additional series tuning capacitance in the in- half of the signal to saturate and clip, which
ductivebranch. TheClapposcillatorisavari- is usually avoided. This is equivalent to a
ation of the Colpitts oscillator. conduction angle of 180 degrees, regardless
of signal amplitude.
class (1) in general, patterns are com-
monly discriminated into different categories class B-D ampliﬁer switched mode am-
according to certain properties they share. pliﬁer where the device is biased at cutoff,
Thecategoriesinwhichagivensetofpatterns and the input signal is large enough to drive
are partitioned are referred to as classes. the ampliﬁer into heavy saturation such that
(2) in object orientation, is an entity that only a small percentage of time is spent in
deﬁnes a set of objects which share the same transition. The ampliﬁer is literally switched
attributes and processes. between cutoff and saturation, and thus the
saturation angle is a signiﬁcant percentage
class fuse See UL classes. of the conduction angle, which is 180 de-
grees. The unﬁltered, broadband output cur-
class A ampliﬁer an ampliﬁer in which rent waveform of a class B-D ampliﬁer re-
the active device acts as a modulated cur- sembles a stepped squarewave. It is impor-
rent source biased midway between satura- tant to note that only frequency related infor-

c
2000 by CRC Press LLC

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