Page 229 - Radar Technology Encyclopedia

219 integrated circuit, semiconductor integrator, analog

range, gallium-arsenide (GaAs) is used. Passive components coherent or predetection integration. If phase coherence can-
are created by the methods of diffusion onto a substrate or not be obtained, or if the complexity and doppler sensitivity
deposition of thin or thick films on it. Active components of the coherent integrator is not desired, the signals may be
(most often field-effect transistors, see IGFET-structure passed through an envelope detector prior to addition of volt-
integrated circuit.), are grown on a high-ohm GaAs sub- ages. This is called video, noncoherent, or postdetection inte-
strate by the methods of ion epitaxy or ion doping. gration. Envelope-detected signals may be converted to
Large capital investments, highly pure materials, and digital form and integrated in accumulating registers. If the
automation of design and manufacture are required for orga- conversion is to one-bit digital form, the process is called
nization of production of semiconductor integrated circuits. binary integration. Signal information may also be combined
IAM using a simple process of accumulating probabilities of detec-
Ref.: Gassanov (1988), p. 26. tion over n trials. This may be termed cumulative integration.
The signal-to-noise ratio is improved by integration,
A silicon integrated circuit is the most common variety of
greatest improvement being obtained in coherent integration,
semiconductor integrated circuit. The use of silicon offers a
where the integrated (S/N) = n(S/N), and S/N is the signal-to-
i
number of technological advantages and makes it possible to
noise ratio per sample at the input. For video integration, the
create integrated circuits with fewer parasitic connections
improvement is less: (S/N) = n(S/N)/L (n), where L (n) is the
i
i
i
between components operating at higher temperatures. Sili-
integration loss. The binary has an additional loss of about 1.6
con circuits are also used in micropower (1 to 300W) inte-
dB relative to video integration. (See also DETECTION).
grated logic circuits, making it possible to reduce the power
DKB
consumed by onboard computer devices, to reduce their
weight and dimensions, and extend operating lives. IAM Skolnik (1980), pp. 29–33; Barton (1988), pp. 69–74.
Ref.: Popov (1980), p. 199. An accumulator (integrator) is a digital summing device,
such as that used in an n-pulse video integrator, either form-
A solid-state integrated circuit is a microwave module that
ing the sum of n pulse amplitudes or counting up to m thresh-
is produced in a combination of different waveguide lines
old crossings before generating an output alarm. SAL
spatially arranged in layers of the dielectric and connected to
Ref.: Barton (1991), p. 4.13.
one another by capacitive, inductive, galvanic, or electromag-
netic connections. Individual functional components (base An analog integrator is the analog unit integrating the pulse
elements) of a solid circuit are based on optimal types of train to improve the signal-to-noise-ratio. The basic compo-
transmission lines for each of them, with optimal junctions nents of analog integrator are delay line with the delay equal
between them. Solid integrated circuits are a promising trend or multiple to the pulse repetition interval t and adder (S)
r
in the development of microwave integrated circuits. At (Fig. I3). In the configuration of the one-cycle integrator
present multistage circuits are used in which the base compo- shown in the figure, here is positive feedback with the feed-
1).
nents are arranged in different stages on individual substrates back coefficient b less then unity, but close to it (b » When
that are little associated electrically. Suspended and coaxial- the signal and noise appear at the input of such an integrator,
waveguide-strip connectors are widely used as the junction the multiple circulation (recirculation) arises and a set of sig-
components. Examples of use of such circuits include solid nals appears at the output that are delayed by the time k·t (k is
r
k
FAR transceiver modules, IFF beacons, frequency mixers, an integer) and multiplied by the factor b . The sum of these
and modulators. IAM signals is taken from the output 1. Such type of an integrator
Ref.: Nagihara E., IEEE Tran.s MTT-30, no. 3, 1982, pp. 235–242. is often called a recirculator.

A very-large-scale integrated circuit (VLSI) is one with a
very large degree of integration, which constitutes a finished
Table I2
item capable of performing the functions of an apparatus (for
Degree of Integration of Very-Large-Scale Integrated
example a microprocessor). In degree of integration, semi-
Circuits
conductor microcircuits with bipolar transistors are inferior to
on IGFET-structure integrated circuits. (See Table I2.) IAM Number of elements
Ref.: Jordan (1985), p. 20.12; Nikolaev (1992), p. 10. Functional Type of integrated or components on
purpose circuit crystal
INTEGRATION, INTEGRATOR. Integration is the pro-
cess of combining n samples of a signal, each accompanied
Digital On IGFET structure More than 10,000
by an independent sample of noise or interference, to improve
the signal-to-noise ratio. The samples may be successive
pulses in a train or pulses received in parallel channels with Digital Bipolar More than 2,000
independent noise. In the case of successive signal samples
having phase coherence, the integration may be performed by Analog Combined (on bipolar More than 300
adding voltages at intermediate frequency or at baseband on and IGFET transistors
I- and Q-samples, before envelope detection. This is called