JPS6020924B2 - Temperature detection circuit for electronic watches - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature detection circuit for an electronic watch equipped with a temperature compensation function. Regarding a detection circuit.

An object of the present invention is to provide a simple temperature detection circuit for an electronic watch, and also to provide the detection circuit with a circuit configuration that can be integrated.

Currently, the quartz crystal oscillator that serves as the time standard for Kameko clocks has temperature characteristics that are particularly dependent on the temperature characteristics of Young's modulus. -10-8 to -10-7 deg2). Therefore, the temperature characteristics of the crystal oscillator are the biggest cause of environmental errors for quartz electronic watches. Conventionally, in order to correct this temperature error, methods such as using a ceramic capacitor with a temperature capacitance change, or setting up a crystal oscillator that serves as a time standard and another oscillator, are used to compensate for the difference in temperature-frequency characteristics between the two. , a method of detecting the temperature and correcting the temperature-frequency characteristics of the reference signal generation source is used.

In the method using a magnetic capacitor, the correction accuracy is determined, of course, by the temperature characteristics of the crystal resonator and the magnetic capacitor.

Therefore, in order to improve accuracy, it becomes extremely burdensome to make efforts to equalize and match each characteristic. Furthermore, in the case of correction using two oscillators, a greater effect in terms of accuracy can be expected than in the case of using a magnetic capacitor.

However, in order to detect temperature, another oscillator is required in addition to the reference signal generation source, and additional circuits such as a detection circuit to detect the frequency difference between two oscillation frequencies are required for temperature detection. , and an associated control circuit is also required, which has the disadvantage that the correction circuit itself becomes large in scale. Therefore, the simplest and most common method is to use a temperature sensing element such as a thermistor.
It is shown in the figure.

In FIG. 1, 101 is a P-cMMOSFET or a P-cMMOSFET.
This is a switch using an NP bipolar transistor or the like.
102 is a temperature sensing element such as a thermistor, 103 to 105 are resistors, and 106 to 108 are C-MOS inverters for temperature detection.

109 is a conversion circuit for converting the temperature from the binary logic outputs 106 to 108.

For the sake of explanation, the resistance values of the thermistors and resistors 102 to 105 at t (°C) are sequentially shown as R2 (t), R8 (t
), R4(t), R5(t), and the junction of 102 and 103 (NODE) is called V powder, V34, V45
If we try to determine R(t)=R2(t)+R3(t
)+R4(t)+R5(t), the power supply voltage is V
If oo, then V23=V.

. (R3(t)+R4(t)+R5(t))/R(t)
V34=V.

. (R4(t)+R5(t))/R(t)V45;V.
.・R5(t)/R(t).

Further, the input threshold voltage of the inverters 106 to 108 at t (° C.) is assumed to be Vtr (t).

Here, the input dark value voltage ytr(t) of the inverter is the input voltage of the inverter when the output voltage of the inverter is inverted, and has temperature dependence. In addition, inverter 10
6, 107, and 108 have the same Vtr(t). Therefore, V23 for inverter 106
If Vtr(t) is greater than Vtr(t), the output of 106 is inverted and becomes L. Under these conditions, t<=Vtr(t
)>V powder (t)>V34(t)>V45(t)LSt<
t2V23(t)ZVtr(t)>V34(t)>V4
5(t) Rami t<t3V23(t)>V34(t)>Vtr(t
)V45(t) Ramit V23(t)>V34(t)>V Monument(t)ZV
The temperature detection circuit was constructed by setting the resistance values of the thermistors 102 to 105 and the resistors so that tr(t) was obtained.

FIG. 2 shows, as a straight line, the changes in Vtr, V23, V34, and V side with respect to temperature changes when the temperature is set in this manner.

In FIGS. 2, 3, 5, and 7, temperature changes in V due to changes in the Helmi level and the like due to temperature are ignored. Also, 106 to 108 C-MOS
Set the output value of the inverter to 1 (High output) or 3 (High output)
The symbols for each temperature range are shown in the table below. Since the above-mentioned detection circuit uses a thermistor, it is not only costly but also difficult to integrate. Thermistor 1
It comes to mind that instead of 02, a resistor having a different temperature coefficient from resistors 103 to 105 is used.

Considering the case of further integration, it is possible to integrate the circuit shown in Figure 1 without using a thermistor by taking advantage of the difference in the temperature coefficient of the resistance value of a low concentration diffused resistor, a high concentration diffused resistor, a MOS resistor, etc. A temperature detection circuit can be implemented. FIG. 3 is a diagram equivalent to FIG. 2 in the case of integration using resistors with different temperature coefficients. When using a thermistor, the thermistor itself has a negative temperature coefficient and the resistor has a positive temperature characteristic, whereas when integrated, the temperature coefficient is slightly different, but
Both have positive temperature coefficients. As a result, by being integrated, it is resistant to temperature changes. V23, V34, V4
Changes in the input value to the C-MOS inverter such as No. 5 are reduced. As a result, there is no margin in determining the resistance values of 102 to 105, and the input threshold value of the C-MOS varies, making it practically difficult to implement. The present invention eliminates the above-mentioned drawbacks, and is an essential condition for use in electronic wristwatches, etc., by a method of controlling the threshold values of a C-MOS inverter to sequentially change as the temperature rises. This realizes the integration of a temperature detection circuit.

4 to 7 show an embodiment of the present invention.

In FIG. 4, 402 to 405 are diffused resistors or MO
S resistance, for example, 402 is a high concentration-diffused resistance,
If 403 to 405 are fabricated using low-concentration single-diffusion resistors, it is possible to obtain a characteristic that V23, V5' on the V side, increases as the temperature rises. On the other hand, 409 to 414 are also integrated resistors, such as 409, 411 and 413.
If the low-concentration single-diffusion resistors 410, 412, and 414 are made of high-concentration single-diffusion resistors, the C-MOS inverter 4
The Pch side source potentials of 06 to 408 have a characteristic of decreasing as the temperature increases. As a result, C-MO for temperature detection
The input threshold voltage of the B inverter decreases as the temperature rises, and a synergistic effect can be provided by increasing the input voltages V34 and V45 on the y side. FIG. 5 is a diagram equivalent to FIG. 2 when the circuit of FIG. 4 is used. 5 and 7, the subscripts in parentheses for Voo, Vss, and Vtr are P-ch, source voltage, n-ch source voltage, and
This is the input threshold voltage.

Figure 6 shows the temperature detection circuit by adding a resistor of 615 to 620 to the circuit of Figure 4 to form a second voltage dividing circuit.
- This is an example of the present invention in which the source potential on the n-ch side of the MOB inverter is also decreased as the temperature rises, and the temperature change in the input threshold voltage is made larger than in the case of FIG. FIG. 7 is a diagram equivalent to FIG. 1 when the circuit of FIG. 6 is used.

Although the example of the invention shown in FIG. 6 has the disadvantage that the number of elements is larger, the effect is greater than that of the example of the invention shown in FIG. Furthermore, in a transparent C-MOS using an n-type substrate, separation of the substrate on the nch side requires an additional step, but it becomes easier if SOS (silicon on sapphire) is used. As described above, the present invention has been developed to replace a temperature detection circuit that used a thermistor with a temperature detection C
- By changing the input threshold voltage of the MOS inverter with the temperature, creating a synergistic effect with the input voltage, and realizing a fully integrated temperature detection circuit, it can be installed in electronic watches that have high demands for miniaturization. This enabled us to contribute to the provision of high-precision electronic clocks.

In the example of the present invention, two types of resistors with different concentrations of diffused resistance were explained, but it is possible that each resistor has a different concentration or has completely opposite characteristics with respect to temperature rise than the example of the invention. There is no problem in having it as long as the synergistic effect described above appears.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a temperature detection circuit using a conventional thermistor.

FIG. 2 shows the temperature-voltage characteristics of the circuit shown in FIG. Third
The figure shows temperature-voltage characteristics when a conventional temperature detection circuit is simply integrated. FIG. 4 shows a temperature detection circuit according to an embodiment of the present invention. FIG. 5 shows the temperature-voltage characteristics of the circuit shown in FIG. FIG. 6 is another embodiment of the invention. FIG. 7 shows the temperature-voltage characteristics of the circuit shown in FIG. Multi-figure 1 Hishi-no-zu 7-figure Fin

Claims (1)

[Claims] 1. In an electronic watch that compensates for the temperature-frequency characteristics of a reference signal generation source based on an output signal from a temperature detection circuit, the temperature detection circuit has a plurality of voltage division points, some of which have different temperature coefficients. a first voltage dividing circuit made up of a plurality of resistor groups including a resistor; a plurality of C-MOS inverters whose gate inputs are outputs from the plurality of voltage dividing points of the first voltage dividing circuit; a second voltage dividing circuit having at least one power supply terminal connected to a voltage dividing point;
The voltage dividing circuit includes resistors having different temperature coefficients, and all the resistors constituting the first and second voltage dividing circuits are formed on the same semiconductor substrate. .