This invention relates to a semiconductor circuit for obtaining a constant voltage as a reference signal using MOS transistors.
Circuits in which a voltage level output by a sensor, or various other types of circuits, is compared with a standard reference voltage to in turn form various control signals are well known. There are various types of reference voltage generation circuits. In general, a power source voltage is divided with resistors R1 and R2 as shown in FIG. 4, and the reference voltage is output from the division point. In an alternative circuit, multiple depletion type (hereinafter abbreviated as D type) MOS transistors 1 are connected in series as substitute for the required resistance, with the reference voltage Vref taken out from an appropriate contact point. However, with the conventional circuit, since the reference voltage Vref is dependent on the power voltage Vcc, the reference voltage varies if the power voltage varies, making the circuit difficult to use.