Oscillators – Ring oscillators
Reexamination Certificate
1996-09-16
2001-02-13
Mis, David (Department: 2817)
Oscillators
Ring oscillators
C331S185000, C331S186000
Reexamination Certificate
active
06188293
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates a ring oscillation circuit of a MOS-IC which operates by undergoing only a small difference oscillation frequency in response to a wide range of power supply voltage level.
The present invention further relates to a non-volatile semiconductor memory integrated circuit (hereafter: EEPROM-IC) which is able to rewrite electrically, and especially to an EEPROM-IC which operates at a wide power source voltage range from low voltage and low power consumption with one power source. The present invention furthermore relates to electronic memory comprising an EEPROM-IC for storing information and powered by battery like solar battery, and especially to a small size and long life electronic memory. A ring oscillation circuit which in which plural odd invert circuits are connected in a ring configuration therein is used in conventional IC.
An EEPROM -IC with one power source, which generates a voltage several times that of the power source voltage for writing and erasing by driving a booster circuit using a ring oscillator is disclosed in Japan patent H05325578A.
As oscillation frequency of the conventional ring oscillation circuit varies greatly according to a change of input power, the variation being higher than is necessary. Thus current consumption of the circuit becomes large if a stable oscillation frequency at low voltage range is required such that the circuit operates over a wide power source voltage range.
In EEPROM with one power source, a voltage higher voltage than that of the power source is generated by a booster circuit by driving a ring oscillator. When the booster circuit is designed to operate at a low voltage like 1V, there is an increase in power consumption in the circuit at high power source voltage. Consequently, a large size solar battery is needed in an electronic device using an EEPROM-IC powered by solar battery. Electronic devices using a dry battery have a problem in that battery life is short.
The object of the present invention is to achieve stable oscillation by controlling the power source voltage of the oscillation circuit and limiting current.
Another object of the present invention is to provide an EEPROM-IC which does not increase its power consumption in accordance with an increase of power voltage at wide power source voltage range from low voltage to high voltage.
Further object of the present invention is to provide an memory which may be written to and erased using small size solar battery.
SUMMARY OF THE INVENTION
To solve the above problem, a constant voltage generating circuit is arranged and operates a ring oscillating circuit at a constant voltage in the present invention. Further, constant voltage generating circuit and constant current element which is controlled by a constant voltage generated by the constant voltage generating circuit are arranged.
The present invention further includes a non-volatile semiconductor memory comprising a memory cell array having memory an means for memorizing non-volatile memory, oscillating circuit comprising plural odd inverting circuits connected in a ring, booster circuit means for boosting a power source voltage by driving of the oscillating circuit and for generating a high voltage pulse for write/erasing of the memory means, and a constant current element connected to the inverting circuits.
The present invention furthermore includes a non-volatile semiconductor memory comprising a memory cell array having memory an means for memorizing non-volatile memory, oscillating circuit comprising plural odd inverting circuits connected in a ring, booster circuit means for boosting a power source voltage by driving of the oscillating circuit, and a constant voltage generating circuit for generating a constant voltage which is applied to the oscillating circuit.
Stable oscillation frequency at low voltage range is gained with the above structure. Even at a high voltage, the oscillation frequency does not change greatly and the circuit is able to decrease current consumption.
As current consumption of memory card comprising plural EEPROM-ICs is within half that of the prior art, it is possible to drive the memory card with a solar battery.
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patent: 5570004 (1996-10-01), Shibata
patent: 5594391 (1997-01-01), Yoshizawa
Kojima Yoshikazu
Miyagi Masanori
Adams & Wilks
Mis David
Seiko Instruments Inc.
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