JPS6230390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a complementary MOS integrated circuit (hereinafter referred to as "complementary MOS integrated circuit") which uses a crystal oscillator as a time reference source and has means for dividing the frequency of the oscillator up to a time display device.
It relates to crystal oscillation type electronic watches using CMOS IC (abbreviated as CMOS IC), and particularly relates to the supply of voltage applied to a part of CMOS IC.

The structure of a conventionally used crystal oscillation type electronic timepiece is as shown in FIG. 1 (composed of an oscillating section 11, a frequency dividing section 12, a display driving section 13, a time display device 14, a power source 15, etc.). Among these, CMOS ICs consisting of oscillation parts, frequency division parts, etc. are equipped with the minimum voltage (hereinafter referred to as VV) required to continue normal operation.
(abbreviated as _eod ) exists. In order to extend the battery life of watches powered by batteries,
It not only reduces the power consumption of CMOS/IC. It is also necessary to lower V _eod . However, CMOS ICs generally have a characteristic that the lower the power consumption, the higher the V _eod , and this makes it difficult to create a CMOS IC that consumes less power and has a low V _eod .

The present invention aims to eliminate the above-mentioned problems by devising a method of supplying voltage applied to a part of the CMOS IC, and one embodiment thereof is shown in FIG. 2. 21, 22, 2 in Figure 2
3, 24, 25 are 11, 12, and 12 in Figure 1, respectively.
Corresponds to 13, 14, and 15. 26 is a circuit or element having constant current characteristics, and 27 is a resistor.
In the example in Figure 2, the threshold voltage of the MOS transistor used in at least the section 21 is set to a smaller absolute value than the threshold voltage of the MOS transistor used in Figure 1, and when the applied voltage is low, However, it is necessary to make it easier to oscillate.

A feature of the present invention is that the power supply voltage is divided by a series connection of a circuit or element having constant current characteristics and a resistor, and the voltage across the resistor is applied to a part of the CMOS IC. Since the resistor 26 has constant current characteristics, even if the power supply voltage decreases, the resistor 27
The sum of the currents flowing through the oscillating section 21 does not change. Assuming that the oscillation section 21 is about to stop oscillating when the power supply voltage is lowered, the oscillation section 21
Since the current flowing through the resistor 27 begins to decrease, the current flowing through the resistor 27 increases accordingly. Therefore, the voltage across the resistor 27 increases, and as a result, the oscillating section 21 becomes susceptible to oscillation again. As long as the constant current characteristic of the constant current characteristic element 26 is not lost even if the power supply voltage decreases, the oscillation section 21
can continue to oscillate, and V _eod will apparently decrease. Regarding power consumption, the current value flowing through the constant current characteristic element 26, the resistance value of the resistor 27,
By appropriately selecting the threshold voltage etc. of the MOS transistor used in the oscillation section
It is possible to prevent the increase from increasing as compared to the case shown in the figure. Further, in the oscillation state, the impedance value of the oscillating section 21 increases and decreases, but when the oscillating section 21 reaches the lowest impedance, the constant current characteristic element 2
Among the currents flowing through the resistor 27, the current flowing into the resistor 27 becomes the minimum, so the voltage across the resistor 27, that is, the voltage applied to the oscillation section 21 becomes the minimum, and the configuration shown in FIG. The system is designed to reduce power consumption in the section 21. Therefore, with the configuration shown in FIG. 2, V _eod can be lowered without increasing power consumption.

In the example of FIG. 2, the voltage across the resistor 27 is applied to the oscillation section, but if applied to another circuit with high input impedance, this becomes a constant voltage source. In this case, even if the power supply voltage fluctuates, the voltage across the resistor 27 does not change, so it is clear that the V _eod of the circuit to which this voltage is applied will apparently rise or fall.

The second feature of the present invention is that an MNOS transistor is used as the element having constant current characteristics, and an example of the circuit configuration thereof is shown in FIG.
In FIG. 3, 301 is an MNOS transistor, and 302 corresponds to the resistance of resistor 27 in FIG. The MNOS transistor has a memory retention property, and once it is turned on, the current passing through the MNOS transistor hardly changes even if the power supply voltage fluctuates. Further, the current value can be set to an arbitrary value by adjusting the amount of charge injected into the gate portion, the threshold voltage, etc.

The MNOS transistor can be formed on the same chip as the CMOS/IC, and if the resistor 302 is formed of a diffusion layer, polycrystalline silicon, etc., all of the additional circuits in the present invention can be formed on the same chip as the CMOS/IC. be able to.

According to the present invention, it is possible to provide a CMOS IC with low V _eod without increasing power consumption, and the effect is very large.

[Brief explanation of the drawing]

Figure 1 is a blocking diagram of a conventional electronic clock. Figure 2 is a configuration diagram showing the configuration of an electronic timepiece according to the present invention, and Figure 3 is a diagram showing the configuration of an electronic timepiece according to the present invention.
FIG. 3 is a circuit diagram of the main part when realized using MNOS transistors. 11, 21... Oscillation section, 12, 22... Frequency division section, 1
3, 23... Display drive section, 14, 24... Time display device, 15, 25... Power supply, 26... Circuit or element having constant current characteristics, 27, 302... Resistor, 301...
MNOS transistor.

Claims (1)

[Scope of Claims] 1. A circuit having constant current characteristics in a crystal oscillation electronic timepiece using a complementary MOS integrated circuit that uses a crystal oscillator as a time reference source and has means for dividing the frequency of the crystal oscillator. Alternatively, a crystal oscillation electronic timepiece characterized in that an element and a resistor are connected in series, a power supply voltage is divided, and the voltage across the resistor is supplied to a part of the integrated circuit. 2. Claim 1, characterized in that the element having constant current characteristics is an MNOS transistor.
The crystal oscillation type electronic clock described in Section 1.