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6.
QÜARTER.SQUANE
Multiplication
tions necessarY in
utilizes
a kind of
cluce a product
of
ing equation:
I
^ r -
I
L+
(EQ. 2.6-1)
The 5o5 Quarter-square Multiplier
is basically
a gated-resistor
circuit
application
of the quarter-square
technique.
},ihen the
quarter-square
nultlplier
is used with three high-gain
anplifiers,
the resultant
circuit
is capable of rnultipli-eation,
division
or squar-'
ing of input variables.
The quarber-square multiplier
ernploys two
squari-ng circuits
uhich utilize
solid
state diodes and precision
re-
sistors
to produce the square of a given input.
Figure 2.6-I
shows
the block diagram of the Multiplier
EM-151, and Figure 2.6-2 is a sjm-
plified
sehematic typical
of one cf the two squaring cireuits
of the
multiplier.
Each diode is reverse-biased
(cut off)
by the negative
reference
source at a potential
dependent on the series resistance
(n4t, ntrZ ...
R6O) in the reference source 1eg.
To eauso a given diode
to conduct,
the sum of the X and Y input
(applied
via the zumrning ampli-
fier)
must attain
a potential
opposite in polarity
and larger
than the
bias of the reference
1eg.
By neans of apptopriate
jnput resistors
@l-, Rz, ... R2o) and bias resistors
(R&t R/+2, ... R6o) the diodes
may be madle to conduct at different
pre-detennined
values of (X+y).
(The potential
at which a gi-ven diode conducts
j-s lmor'rn as the diode
breakpoint ) .
MÜLTIPT,MR EM-151
of tr,lo variables
i-s one of the non-linear
opera-
a general purpose computer.
The 505 Multiplier
quarter-square
nrultiplication
techniques to pro-
two variables
(X and Y) as i-1lust'rated
by the follow-
t
t
t
t
t
t
t
I
I
t
I
I
I
I
I
[
, ' ^ '
Ä ^ r l
I (xrv+r)2 - (x-Y+r;2 - 4Y I
L
)
- 5 6 -
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