Abstract: A converter includes a voltage selector which employs IGFETs as voltage switching elements, and a controller which controls the IGFETs. Each of the IGFETs in the voltage selector is made either the P-channel type or the N-channel type, depending upon a voltage level to be thereby switched and a level of a binary signal supplied from the controller. As a result, a voltage of comparatively great level can be switched by a binary signal of small level amplitude.

Abstract: A depletion type MISFET is connected between a power voltage supply line of a transistor logic circuit block and a power source voltage terminal. The gate electrode of the depletion type MISFET is connected to a reference voltage. The transistor logic circuit block has a driving MISFET and a load connected in series between the power voltage supply line and the reference voltage. The load of the transistor logic circuit is similarly constituted by a depletion type MISFET, while the driving MISFET is of enhancement type. The driving MISFET and the load MISFET in the transistor logic circuit block are built-in in a monolithic semiconductor integrated circuit, together with the MISFET for the power voltage supply to the transistor logic circuit.