Nippon Precision Circuits Inc.

Masahisa Kimura

Kazuhisa Oyama

Eiichi Hasegawa

Kunihiko Tsukagoshi

An oscillation control circuit is offered which can improve the startability of an oscillator circuit operating at high frequencies and at a low power-supply voltage. When the oscillation potential of the oscillation signal is between the inversion potential (1.2 volts) of a CMOS inverter IV and the inversion potential (1.8 volts) of a CMOS inverter IV the logical output value of a CMOS Schmitt inverter SI is 1. The output of a CMOS inverter formed by MOS transistors T and T is shorted out via a MOS transistor T Its logical output value is kept at 1. When the inversion potential of the CMOS inverter IV or the inversion potential of the CMOS inverter IV is exceeded, if the input voltage to the CMOS Schmitt trigger SI increases above its inversion potential (1.8 volts), the logical output value assumes a value of 0. The CMOS inverter formed by the MOS transistors T and T is first set into operation. The oscillation signal is inverted, setting a circuit LA at a later stage into operation.

Oscillation control circuit

An oscillator circuit adapted for a piezoelectric oscillator which has a weak oscillation output for generating high frequencies is provided. The speed of operation of the oscillator circuit is increased. An integrated circuit for such an oscillator circuit is also provided. The oscillator circuit has an amplifier portion consisting of CMOS inverters connected in cascade. MOS transistors forming the CMOS inverters have channel widths that decrease successively from the first stage to the last stage to improve the amplification factor of the amplifier portion at high frequencies. This makes it possible to amplify weak oscillation output from the quartz oscillator (XL). A filter circuit produces a peak of negative resistance at a frequency higher than conventional. This permit oscillation operation at higher frequencies.

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Tokyo, Japan

Masahisa Kimura