Abstract: A voltage-controlled oscillator generates an oscillation signal having a frequency corresponding to a control signal. A phase comparator detects a phase difference between a reference signal and a frequency-divided signal derived from the oscillation signal and generates a phase difference signal. A control circuit, which comprises an A/D converter, a high-speed processor, and a D/A converter, generates a control voltage so as to reduce a time-dependent change in the phase difference signal to synchronize the oscillation signal with the reference signal. When the synchronization of the oscillation signal with the reference signal is completed, the control circuit secures a control voltage at the time time-dependent change in the phase difference signal becomes equal to or smaller than a phase difference stored in a flash ROM.

Abstract: A current control circuit for a dynamic random access memory device which has a bit line sense amplifier for sensing and amplifying bit data on a bit line, and a data bit clamping circuit for supplying current to the bit line sense amplifier. The current control circuit is adapted to control the current from the data bit clamping circuit to the bit line sense amplifier. The current control circuit comprises a first path switching circuit for forming a current path from the data bit clamping circuit to the bit line sense amplifier during a refresh operation, a second path switching circuit connected between the first path switching circuit and the data bit clamping circuit, for opening/closing the current path, and a path controller for generating a current control signal in response to an address signal and supplying the generated current control signal to the second path switching circuit.