| 摘要 |
PURPOSE:To simplify the constitution of a circuit and to improve the accuracy of conversion of an execution value by providing a squaring circuit, an averaging circuit and a differential amplifier. CONSTITUTION:A squaring current (i) is led into the output part 21 of a squaring circuit 2 and a negative feedback voltage V0 is inputted to a negative feedback input part 22. An AC voltage e0 from an input terminal IN is fully rectified 1 and the rectified voltage is inputted to one input of an operational amplifier AMP in the averaging circuit 3 and the other input of the amplifier AMP is connected to the output part 21 of the circuit 2. The output part of the amplifier AMP is connected to one input of the differential amplifier circuit 4 and the other input terminal is connected to the output part 21 of the circuit 2. A main current Ii corresponding to a voltage difference between the rectified voltage e1 and the earth potential or a voltage difference between the voltage e1 and the voltage V0 is made to flow into a main path A including the resistor R of the circuit 2. Subcurrents I2, I3 between a voltage point lower than the voltage e1 and the earth part or between the low potential point and the input part 22 are supplied into subpaths B, C respectively. Thus, the constitution of the circuit is simplified and the highly accurate effective value conversion can be attained. |
