Hitachi 505 Operation Manual page 64

As the input
(X + y) reaches the breakpoint of each diode, the
input resistors are essentially
para11e1ed. The gain of the opera-
tional amplifier
changes as each diode conducts; therefore,
rqr proper
sefection
of components, the network of Figure 2.6-2 can simulate a
curüe of (X + Y)2 with straight-line segments. The number of seg-
mants used deterrnines the accuracy of the approximation.
In 505 Multipliers, two squaring circuits are required in order
to accomplish four quadrant rnultiplication, because X+Y+l and X-Y+1
should be squared individually.
Figure 2.6-3 is a simplified
schematic of the quarter-square
multiplier showing the patching tenninatj-ons
and the patching btock
area of the Pre-Patch Pane1. For rnultiplicati-on,
division or squaring,
a bottle plug is placed as shomr in tr'ig:re 2.6-/, and 2.6-5 respecti-ve1y.
Note in each case the syrnbols of t,he area the plug to placed indicates
the function
that may be perforrned.
a. Multiplication
Figure 2.6-/u illustrates the patching procedure for rirultiplica-
tion
of two variableso
X and Y. Two inputs
(X anA Y) are necessary
notwithstanding
the polarity.
Note that the output voltage
from the third amplifier
is -XY/400
due to the inversion of the emn'lifier.
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