PURPOSE: To convert the waveform of an input signal accurately, by using a voltage division circuit comprising resistors and a constant current source, and setting a threshold level lower or higher by a prescirbed DC voltage than the DC component voltage of the input signal at all times even if the DC component of the input signal in which an AC component is superimposed on the DC component.
CONSTITUTION: A DC voltage V0 of a voltage signal V1 is changed, a level difference Vd is changed by a product of R3 and ΔI0 by a change of a constant current from the constant current source I0 through the effect of the DC voltage change. Since the constant current source has the property substantially that a constant current flows even if the applied voltage is fluctuated, the change I0 in the constant current is very small with the change ΔV0 in the DC component V0 at an input terminal T1', and the ΔVd is suppressed very small. Thus, an accurate angular signal V2 is obtained without shifted rise and fall of a waveform V2 after wave form shaping.
ARAKAWA MIYAO
SATOU SHINKOU
TAGUCHI YASUO
TOKYO SHIBAURA ELECTRIC CO