Other

Hitachi, Ltd.

Akimitsu Mimura

Tsugio Takahashi

Yuji Yokoyama

Masayoshi Nomura

An oscilator circuit for a integrated circuit memory device to optimize the refresh operating circuit and suppress wasteful power consumption in which the oscillator frequency is set high during high temperatures and the oscillator frequency is set low during low temperatures. A current I,is generated by means of the current source,having characteristics in which it is increased during high temperatures and decreased during low temperatures, and is supplied to the ring oscillator,. A current corresponding to the current I,is supplied to each inverter in the frame oscillator,, and since the oscillator frequency is controlled by means of the current value of the supplied current, the frequency of the clock signal CLK generated increases accompanying a rise in temperature, and since the refresh operation is conducted based on the clock signal CLK, the data holding capabilities can be ensured during high temperatures, wasteful power consumption can be reduced during low temperatures, and optimization of the refresh operating frequency can be realized.

Oscillator circuit for a semiconductor memory having a temperature dependent cycle

A first periodic pulse is rectified to generate an internal voltage by a charge pump circuit. A level detector is provided for detecting whether or not the internal voltage reaches a desired level. The charge pump circuit is controlled by a controller in accordance with the detection signal so that the internal voltage may take the desired level. A switch element switched by a second periodic pulse is provided in the current path of the level detector. A leakage current path for allowing a lower electric current than the electric current to flow through the former current path is provided between the output terminal of the charge pump circuit and a predetermined power supply terminal.

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Ome, Japan

Akimitsu Mimura