JPS61104233A - Temperature measuring circuit - Google Patents

Abstract

PURPOSE:To simplify the constitution of the titled circuit, by counting the oscillation signal of a ring oscillator, of which the oscillation frequency changes in proportion to temp., over the time, which is obtained by utilizing a timing frequency dividing circuit, by a preset counter. CONSTITUTION:The output of a quartz oscillation circuit 101 is divided in its frequency by a frequency dividing circuit 102 until a timing unit signal is obtained and the content of the frequency dividing circuit 102 is compared with the content, which was set by an external setting means A103, by a comparing circuit 108. The output of the comparing circuit 108 resets a preset latch 109. An incremental counter B107 preset by an external setting means B104 counts the oscillation signal of a ring oscillator 105 of which the oscillation frequency changes in proportional to temp. only over a period when the output of the latch 109 is high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the configuration of a temperature measurement circuit in a timepiece IC.

[Conventional technology]

Conventionally, when configuring a temperature measurement circuit on an integrated circuit, for example, PM
Digital temperature information was obtained from the temperature characteristics of the forward voltage of the junction using an A/D converter.

[Problem that the invention seeks to solve]

However, with the above-mentioned conventional technology, the bias of the forward voltage! Disadvantages include variations in slope, and the need for a circuit that requires a large pattern area and large operating current, such as an A/D converter, and cannot be applied to products that require low current consumption, such as watches. It had

The present invention is intended to solve the above-mentioned drawbacks, and its purpose is to provide a temperature measuring circuit with low current consumption, compatible with watchmaking equipment, easy to 1 adjustment, and high accuracy, with a small pattern area. be.

[Means for solving problems]

The temperature measuring circuit of the present invention counts the oscillation IT of a ring oscillator whose oscillation frequency changes in proportion to the temperature by a preset counter for a desired time obtained using a time dividing circuit. It is characterized by obtaining temperature information.

[Effect]

According to the configuration of the present invention, even if the slope or absolute value of the oscillation frequency of the ring oscillator changes, the change can be absorbed by external settings. It can be set according to the state of the circuit, and furthermore, the pattern area and operating current of the ring oscillator can be made sufficiently smaller than those of an A/D converter or the like.

〔Example〕

FIG. 1 shows an embodiment of the present invention. The output of the crystal oscillation circuit 101 is frequency-divided by a frequency dividing circuit 102 to a time measurement unit signal. The contents of the frequency dividing circuit 102 are compared by the comparison circuit 108 with the contents set by the external setting means AlO3.

The output of comparison circuit 108 resets preset latch 109. Therefore, output 1 of latch 109
The time τ for which 10 is Hlgh is given by τ = -A - (seconds) (1) where A is The contents of setting A are expressed in decimal.

Next, if the output frequency of the ring oscillator 105 which outputs a frequency proportional to the temperature is /R, the number of pulses PN of the output of the gate 106 is pN=τ-7m (2). The contents of the up counter B107 preset by the external setting means B104 are N=PH+B=Tf&+B (3).

Therefore, now the oscillation frequency /R of the ring oscillator is

'fn=to,
θ + k2 (Hz) (4) If θ is the ambient temperature, then N becomes H=1τ·θ+(k2τ0B) (5), and N becomes data proportional to temperature.

The slope of the ring oscillator with respect to temperature, 1, can be adjusted by changing the value of τ, that is, A, and k2 can be adjusted by both A and B.

Next, the number of constituent bits of up counter B107 is .

In the case of bits, equation (5) becomes H=, τθ+(k2τ0B)−2j・work (0)work: over 70−number of times. Therefore, for example, kx=20. When =4500, θ=0 (℃) and N=0. N=50 at θ=50℃
In order to do this, in the case of No = 5, 50 = 20 - τ ・
From 20, τ= 0.125→A=512 and 50=20−T・50+(4500・τ+B)−
From 2'・work, J3 = 2.5 work = 20, and since B can only take an integer value, B = 2 or 5. The number of overflows is 20.

From equation (6), it can be seen that the resolution of the slope adjustment of the ring oscillator 105 is inversely proportional to the maximum frequency division frequency applied to the comparator circuit 10, and proportional to the number of comparison bits of the comparator circuit 108. Further, the resolution of the adjustment of 2 to the absolute value is proportional to the number of bits of the up counter 107.

Next, the ring oscillator will be explained with reference to FIGS. 2 and 3. FIG. 2 is a configuration diagram of a ring oscillator whose oscillation frequency changes in proportion to temperature. 1 by the depression transistor 201; CM OS inverters 20j, 203, 2.04 are driven with constant current,
Resistors 205, 207° and 209 are well resistances, and the container 20
6, 208, 210 is a container for a gate structure. FIG. 3 shows the temperature-frequency characteristics of the circuit shown in FIG. 2.

The characteristics shown in FIG. 3 are for the case where the well resistance is 100 Ω and the capacitance is 5 pF, and the difference in slope and absolute value of ρ is considered to be due to variations in IC manufacturing. Further, the constant current value of the depletion transistor 201 was set to about 100 sA.

FIG. 4 shows another 614 example of a ring oscillator. A bias circuit 414 is formed by a depletion transistor 401 and a transistor 402, and the output of the bias circuit drives a constant current transistor 403, and CMOS inverters 404, 405, 4 of a ring oscillator are used.
[Effects of the Invention] As described above, according to the present invention, in order to create the time for counting the ring oscillator il1 using a clock frequency dividing circuit, the circuit rnj is simple. Furthermore, by making the counting time [fiJ] variable by an external setting means, the slope of the ring oscillator output signal frequency with respect to temperature can be detected, and the resolution of temperature information can be freely determined.

Furthermore, by using a presettable up-counter, it is possible to adjust the offset of the output signal of the ring oscillator, and by using the overflow of the up-counter, it is possible to set the temperature '1n signal N=0 at a desired temperature. .

Also, the area occupied by the ring oscillator is, for example, 6 bits.
It is less than half that of an A/D converter, and
There are no manufacturing difficulties. Furthermore, the operating current of the ring oscillator is as small as about 100 sA, and by performing sampling operation, the average operating current can be made sufficiently small.The scope of use of the circuit of the present invention is not limited to watches, but also for thermometers and It is very spacious and can be used for business purposes.

Examples of external setting means include fuses and IICFROM.

11'AMO3, bonding, etc. are not limited.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the circuit of the present invention. Figure 2 is a diagram showing an example of a ring oscillator circuit.
. FIG. 3 is a diagram showing the temperature frequency characteristics of the ring oscillator shown in FIG. 2. FIG. 4 is a diagram showing another example of a ring oscillator circuit. 111: Control circuit 407-4o9: Resistor 410-412: Capacitor or higher

Claims (1)

[Claims] A crystal oscillator circuit, a frequency divider circuit that creates a time measurement unit signal from the output signal of the oscillation circuit, a ring oscillator whose oscillation frequency changes in proportion to temperature change, and external setting means B;
It has a counter B preset by the external setting means B, an external setting means A, and a comparison means for comparing the setting contents of the external setting means A and the contents of the frequency dividing circuit, and the output of the comparison means A temperature measurement circuit characterized in that the output signal of the ring oscillator is counted by the counter B in accordance with the above.