US-12625012-B2 - Temperature sensor device

Abstract

A temperature sensor device is capable of measuring minute temperature changes while being manufactured at low cost without needing a high performance IC tester. A temperature sensor device includes a temperature sensor circuit 2 and a temperature sensor 1 . The temperature sensor 1 includes a PN junction element 15 which is a temperature sensing element, a variable current source which supplies different forward currents of at least two values to the PN junction element 15 and a constant voltage source 16 which outputs a constant voltage having the same temperature properties as a forward voltage of the PN junction element 15.

Inventors

• Tsutomu Tomioka
• Tadakatsu Kuroda
• Makoto Mitani
• Naohiro Hiraoka

Assignees

• ABLIC INC.

Dates

Publication Date

20260512

Application Date

20231030

Priority Date

20230131

Claims (4)

1. 1 . A temperature sensor device, comprising: a temperature sensor circuit; and a temperature sensor, wherein the temperature sensor comprises a PN junction element, configured to be a temperature sensing element, a variable current source, configured to supply different forward currents of at least two values to the PN junction element, and a constant voltage source, configured to output a constant voltage having the same temperature properties as a forward voltage of the PN junction element, wherein the temperature properties comprise a rate of change of voltage with temperature.
2. 2 . The temperature sensor device according to claim 1 , wherein the temperature sensor outputs different forward voltages of at least two values of the PN junction element and the constant voltage.
3. 3 . The temperature sensor device according to claim 2 , wherein the constant voltage is set in consideration of the different forward voltages of the at least two values of the PN junction element, an amplification factor of an amplifier of an inspection device and capability of a voltmeter.
4. 4 . The temperature sensor device according to claim 1 , wherein the constant voltage is set in consideration of different forward voltages of at least two values of the PN junction element, an amplification factor of an amplifier of an inspection device and capability of a voltmeter.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the priority benefits of Japanese application no. 2023-012491, filed on Jan. 31, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. BACKGROUND Technical Field The present invention relates to a temperature sensor device. Description of Related Art Temperature sensors used in various applications have to measure minute temperature changes. For example, the temperature detection accuracy may need to be higher than 1° C. FIG. 5 is a circuit diagram illustrating a conventional temperature sensor 500. The temperature sensor 500 obtains a temperature from a difference in a forward voltage when forward currents I1 and I2 of different current values are passed through a diode 51, which is a temperature sensing element (see, for example, Patent Literature 1 (U.S. Pat. No. 3,812,717)). A voltage difference ΔVo (Vo1-Vo2) output from the temperature sensor 500 is represented by A(KT/q)ln(N). Here, Vo1 is a voltage obtained by amplifying the forward voltage when the forward current I1 is passed through the diode 51 by an amplifier 52; Vo2 is a voltage obtained by amplifying the forward voltage when the forward current I2 is passed through the diode 51 by the amplifier 52; k is the Boltzmann constant; t is an absolute temperature, q is an electronic charge; A is an amplification factor of the amplifier; N is the forward current ratio I1/I2; and In is the logarithm with Napier's number e as the base, that is, the natural logarithm. A temperature T is expressed as qΔVo/{kAln(N)}, and a temperature coefficient dΔVo/dT is expressed as dΔVo/dT=A(k/q)×ln(N). k=1.38×10−23[J/K], q=1.60×10−19[C], and when N=2, the temperature coefficient dΔVo/dT is about to be A×60[μV/K]. A conventional temperature sensor such as the temperature sensor 500 may measure a temperature with high accuracy because a difference in forward voltages of a diode is directly proportional to an absolute temperature. However, a general IC tester used for a shipping inspection has resolution of 1° C. or more for an applied temperature. Thus, in the case of manufacturing a temperature sensor which measures minute temperature changes, a high performance IC tester which applies a temperature with high resolution is critical in the inspection process. A high performance IC tester is more expensive than a general IC tester, so manufacturing costs of a high performance IC tester are higher than manufacturing costs of a general IC tester. In addition, in the case of measuring a minute temperature change, for example, a temperature change of 0.1K, the temperature coefficient dΔVo/dT is A×6[μV/0.1K]. At this time, in order to obtain a voltage change (temperature coefficient of 600 μV/0.1K) measurable by a general voltmeter such as an IC tester, an amplification factor A of an amplifier has to be set to 100 or more. On the other hand, in the case of forward voltages Vf1 and Vf2 of a diode being about 0.6V at a certain temperature, the output voltage of the amplifier with the amplification factor A of 100 or more is 60V or more. That is, in order to measure the voltage output by the amplifier, a high voltage needs to be measured with high accuracy. Thus, the conventional temperature sensor needs a high performance voltmeter in the IC tester used in the inspection process, resulting in high manufacturing costs. As means for solving the problem, it is conceivable that the output voltage of the conventional temperature sensor is digitally processed and output. However, since the conventional temperature sensor obtains the temperature from forward voltages of different two values to increase the accuracy, a resistor for storing temperature data needed for digitization becomes large. A large resistor increases a product cost. The present invention is intended to provide a temperature sensor device capable of measuring minute temperature changes while being manufactured without using a high performance IC tester. SUMMARY A temperature sensor device according to an aspect of the present invention includes a temperature sensor circuit and a temperature sensor. The temperature sensor includes a PN junction element which is a temperature sensing element, a variable current source which supplies different forward currents of at least two values to the PN junction element and a constant voltage source which outputs a constant voltage having the same temperature properties as a forward voltage of the PN junction element. The present invention may provide a temperature sensor device which is capable of measuring minute temperature changes while being manufactured without using a high performance IC tester. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a temperature sensor device of the present invention. FIG. 2 is a graph illustrating temperature properties of forward voltages Vf1 and Vf2 and a constant vol