JPS5633765A - Absolute value circuit - Google Patents

Abstract

PURPOSE:To obtain the signal regarding the absolute value and the polarity of the high-accuracy input signal through a simple constitution of the circuit, by providing the switch element, the voltage comparator and the like. CONSTITUTION:The switch element 9 possesses two terminals 90 and 91 to be controlled plus the control terminal 92. And with application of the positive voltage to the terminal 92, a short circuit is secured between the terminals 90 and 91. And when the voltage of the terminal 92 becomes zero, an open state is secured between the terminals 90 and 91. In the voltage comparator 7, the output terminal 72 has the positive voltage when the voltage applied to the adverse- phase input terminal 70 is lower than that of the same-phase input terminal 71; While the voltage of the terminal 72 becomes zero vice versa. For instance, if the voltage ei at the point A and obtained from the input signal source 1 is positive, the voltage of the terminal 72 in the comparator 7 becomes zero. And thus the element 9 becomes open. Accordingly, the voltage of the same-phase and adverse-phase input terminals 21 and 20 become equal to the voltage ei under ei (>=0) defined for the voltage at the point A. And as a result, the voltage eo obtained at the output terminal 23 becomes equal to the voltage ei. And then eo=-ei is obtained under ii<0, and this shows that a conversion of eo=¦ei¦ has been given.