With the widespread use of home video and other equipment, it is strongly desired to realize a high-frequency monolithic IC active RC filter. This paper proposes a method of constructing the integrator with voltage-controlled current source operated by a single 5-V supply. Even though operated by a single 5-V supply, the proposed integrator can realize a wide dynamic range due to an elaboration in the output circuit. For a cutoff frequency of 1 MHz, the maximum input voltage for distortionless output voltage is 1.0 VP-P. By a simple compensation, an excellent high-frequency characteristic exceeding 2 MHz is obtained. The proposed integrator is of a variable characteristic with differential inputs, and, consequently, an automatically tunable leapfrog-type filter can be realized. To evaluate the performance of the proposed integrator, a high-frequency analysis and a computer simulation were made. The integrator was realized as a monolithic IC by the general-purpose process for home-use equipment, and the automatically tunable filter was constructed. The experimental result agreed well with the theory, indicating that the whole filter can be realized by a monolithic IC.