Page 78 - Electrical Engineering Dictionary

for a patent for the device in 1948 they called sponse to an applied field. The response to an
it a germanium transfer resistance unit; hence external magnetic field is randomly discon-
the name transistor. This device was a sig- tinuous as domains “stick,” and then release.
nificant step in the development of integrated Barkhausen noise is particularly important in
circuits. Bardeen’s second Nobel, which he very small heads and thin-film heads where
shared with Leon Cooper and John R. Schri- very few domains are involved; in larger
effer, was for his work at the University of heads the effects of many domains tend to av-
Illinois in describing the theory of supercon- erage out and Barkhausen noise is relatively
ductivity. less important.

bare-hand refers to a method of servic- barrel distortion a geometric distortion
ing energized overhead conductors in which of a raster display in which vertical lines ap-
the line worker’s body is maintained at the pear to bow outward away from the display
same potential as the conductor on which he center line. The bowing of the vertical lines
is working, thus enabling the conductor to be increases as the distance from the vertical
contacted without danger of shock. center increases. The appearance of these
vertical lines is similar to the staffs of a bar-
BARITT barrier injection transit time, a rel. Barrel distortion is a result of the over-
microwave transit time device that uses injec- correction for pincushion distortion.
tion over a forward biased barrier and transit
time delay through a reverse biased junction
barrel shifter an implementation of a
to produce negative resistance at microwave
shifter, which contains log 2 (max number of
frequencies, useful in low power and self-
bits shifted) stages, where each stage shifts
oscillating mixer applications.
the input by a different power of two number
of positions. It can be implemented as a com-
Barkhausen criterion two conditions
binational array with compact layout that can
placed on a feedback oscillator necessary for
shift the data by more than one bit using only
sustained oscillation. The Barkhausen crite-
one gate. For instance, for a 4-bit word, it
rion states
can execute instructions shl, shl2, shl3, and
1. The total loop amplitude transmission
shl4. This shifter lends itself well to being
factor must be at least unity.
pipelined.
2. The frequency of oscillation will be that
frequency characterized by a total loop phase
barrier layer layer of deposited glass
transmission factor of N2π radians. N is ei-
adjacent to the inner tube surface to create a
ther zero or an integer. Simply, for sustained
barrier against OH diffusion.
oscillation, a disturbance that makes a com-
plete trip around the feedback loop of the os-
barrier voltage a voltage that develops
cillator must be returned at least as strong
across the junction due to uncovered immo-
as the original disturbance and in phase with
bile ions on both sides of the junction. Ions
that disturbance.
are uncovered due to the diffusion of carriers
across the junction.
Barkhausen effect the series of irregular
changes in magnetization that occur when a
Bartlett window a triangular window
magnetic material is subjected to a change in
w[n] of width 2M defined as follows:
magnetizing force.
Barkhausen noise noise arising in mag- w[n]=

netic read heads because the interlocking 1/2[1 + cos(πn/M)], −M ≤ n ≤ M
magnetic domains cannot rotate freely in re- 0, otherwise
c
2000 by CRC Press LLC