GB939486A - Input converter for analogue multipliers - Google Patents

Abstract

939,486. Electron analogue computers. A. NATHAN. June 2, 1960, No. 19606/60. Class 37. [Also in Group XL (c)] An input converter converts two signals x, y to be multiplied in a multiplier into such a form that multiplication of x and y can be carried out in the multiplier for values of x and y in all four quadrants even though the multiplier itself may be only a half, one or two quadrant multiplier. Two functions, #, # are generated by the converter satisfying the following equations and conditions #=max [ [ x |, |y |], #=min [max (x, - y), max (- x, y)] or equivalently | #|=min [ j x | , | y | ] and #, #=xy, ##o, ##|# and the sign of # is equal to that of xy. The terms " max " and " min " are used as operators, i.e. to indicate the " larger of x and y " for example. An embodiment of a converter for generating # and # is shown in Fig. 2, where x and y are applied to inverters A 1 , A 2 so as to produce -x, -y at T 2 , T 4 . Diodes D 1 . . . D 4 are connected as shown to act as amplitude selection circuits, D 11 being a diode to compensate for the voltage drops across the other diodes, so that the output at T n will correspond to #. Diodes D 5 . . . D 9 are so connected as to produce a voltage corresponding to # at T. Transistor circuits are given (Figs. 3b, 3d, not shown), which can replace the diode circuits. Specification 939,487 is referred to.