Patent ID: 7397282

Claim:
A semiconductor integrated circuit device comprising: a logical circuit comprising a first MIS transistor of a first conductivity type and a second MIS transistor of a second conductivity type, said first and second MIS transistors being formed on a semiconductor substrate; a control circuit for controlling a threshold voltage of an MIS transistor included in said logical circuit; an oscillation output circuit comprising a third MIS transistor of said first conductivity type and a fourth MIS transistor of said second conductivity type formed on said semiconductor substrate, by which a frequency of an oscillation output can be changed; a first switching circuit; a second switching circuit; and wherein a clock signal having a predetermined frequency and an oscillation output of said oscillation output circuit are input to said control circuit, said control circuit compares said frequency of said oscillation output with said frequency of said clock signal and generates a first control signal and a second control signal, said oscillation output circuit is controlled by said first and second control signals such that said frequency of said oscillation output corresponds to said frequency of said clock signal, frequency control of said oscillation circuit is performed by controlling a threshold voltage of said third MIS transistor by said first control signal and by controlling a threshold voltage of said fourth MIS transistor by said second control signal, said first control signal is input to said first switching circuit and said first switching circuit outputs a third control signal corresponding to said first control signal, said first control signal is input to said second switching circuit and said second switching circuit outputs a fourth control signal based on said first control signal, and a threshold voltage of said first MIS transistor is controlled by said third control signal and a threshold voltage of said second MIS transistor is controlled by said fourth control signal.