TWI449889B - Temperature sensing apparatus and methods - Google Patents

Description

Temperature sensing device and method

The present invention relates to a temperature sensing device and method, and more particularly to a temperature sensing device and method using a leakage current as a sensing mechanism.

With the advancement of semiconductor manufacturing technology in the middle and late 20th century, integrated circuits began to show rapid growth. Many high-tech electronic products use integrated circuits as their control core, such as the most advanced microprocessor or multi-core processor. An implementation of a body circuit. Among them, in order to avoid problems such as malfunction of the integrated circuit overheating, it is necessary to install a temperature sensor in the integrated circuit.

However, as the development of integrated circuits tends to be smaller and faster, it is more difficult to add a temperature sensor to an integrated circuit. Conventional temperature sensor technology uses nothing more than a Bipolar Junction Transistor or a Complementary Metal Oxide Microelectromechanical System (CMOS-MEMS) as a temperature sensing mechanism.

Due to the inherent limitations of the integrated circuit, the above temperature sensing mechanism is difficult to implement in the integrated circuit. However, integrated circuits must respond in a timely manner to the current temperature to ensure that all functions are functioning properly. Therefore, designing a temperature sensing device that can be easily realized and easily commercialized is indeed a problem and a challenge currently faced.

In view of the above problems of the conventional temperature sensor, the object of the present invention is to provide a temperature sensing device and method for solving the problem that the conventional temperature sensing device and method are difficult to implement in an integrated circuit.

In accordance with the purpose of the present invention, a temperature sensing device is provided that includes a leakage current generating module, a reference current generating module, a voltage comparison module, and a relaxation oscillator. The leakage current generating module includes a metal oxide semiconductor capacitor operating in the reverse region and generates a leakage current proportional to an absolute temperature. The reference current generation module outputs a reference current that does not vary with temperature. The voltage comparison module includes a first current mirror and a second current mirror respectively coupled to the leakage current generating module and the reference current generating module, wherein the reference current and the leakage current are input through the resistor and the capacitor After the voltage is generated, a voltage comparison is performed. The flaccid oscillator is coupled to the voltage comparison module, and generates a pulse wave output according to the comparison result of the voltage comparison module. The temperature sensing device further includes a duty cycle adjuster coupled to the relaxation oscillator and inputting the pulse waveform output.

According to the object of the present invention, a temperature sensing method is further applied to a circuit, wherein the circuit comprises a leakage current generating module, a reference current generating module, a voltage comparing module and a relaxation oscillator, and the temperature sensing The method includes the following steps: comparing a leakage current generated by the leakage current generating module and a reference current generated by the reference current generating module by using the voltage comparison module; and comparing the results of the voltage comparison module according to the foregoing The flaccid oscillator produces a pulse form output.

Wherein, the foregoing temperature sensing method further comprises the following steps: using a first electric The flow mirror and a second current mirror respectively replicate the leakage current and the reference current; and adjust a duty cycle of the pulse waveform output by using a duty cycle adjuster.

According to the present invention, the temperature sensing device and method can have the following advantages: the temperature can be measured simply and accurately, and can be easily realized on the integrated circuit, and further has a circuit layout area and power. The advantage of being less expensive.

Specific examples are given below to explain the contents of the present invention in detail, and the drawings are used as an auxiliary explanation. The symbols mentioned in the description refer to the schema symbols.

Please refer to FIG. 1 , which is an embodiment of a leakage current generating module of the present invention. As shown in FIG. 1, the metal oxide semiconductor capacitor includes a gate 10, an oxide 11, a source terminal/汲 terminal 12, a P-type substrate 13, and a back electrode 14, wherein both ends of the capacitor are gated and oxidized. The objects 11 are separated. A metal oxide semiconductor capacitor is characterized by the use of a gate oxide as a dielectric material that allows leakage current to tunnel through the gate oxide. Therefore, the present invention performs the operation in the reverse region by utilizing the physical characteristics of the above metal oxide semiconductor type capacitor. That is, the source terminal of the metal oxide semiconductor transistor is connected to the 汲 terminal and a voltage is applied to the gate 10. When the transistor operates in the reverse region, the interface trap density is charged and discharged to form a leakage current. The present invention realizes a leakage current generating module by the operation of the foregoing metal oxide semiconductor capacitor as a basis for sensing temperature in the temperature sensing device. However, it should be apparent to those skilled in the art that a current proportional to absolute temperature can also replace the aforementioned leakage current without departing from the spirit and scope of the present invention. It is the basis for sensing temperature.

Please refer to FIG. 2, which is a structural diagram of the overall system implementation of the present invention. As shown in FIG. 2, a leakage current I21 and a reference current I22 are compared with a voltage comparison module 33, and the comparison result is outputted to a frequency 36, and the frequency 36 is used to indicate the temperature sensing result. . The leakage current I21 is a current proportional to the absolute temperature, and the reference current I22 does not change due to the temperature fluctuation, and maintains a constant value.

Please refer to FIG. 3, which is a block diagram of the present invention. As shown in FIG. 3, the leakage current generation module 31 generates a leakage current proportional to an absolute temperature, and the reference current generation module 32 generates a reference current that does not change with temperature, the leakage current and the aforementioned reference. The current input voltage comparison module 33 performs voltage comparison, and outputs the result as a pulse wave output through a relaxation oscillator 34. Finally, the duty cycle output is adjusted by the duty cycle adjuster 35, and the adjustment is performed. The duty cycle is preferably 50%. After passing through the duty cycle adjuster 35, the result of the comparison is finally output to a frequency 36, and the frequency 36 is used to represent the sensing result of the temperature.

Please refer to FIG. 4, which is an embodiment of the circuit structure diagram of the present invention. As shown in FIG. 4, the leakage current generating module 31 includes a metal oxide semiconductor capacitor 41. The metal oxide semiconductor capacitor 41 operates in the reverse region, and is charged and discharged through the interface trap density to form a leakage current. The leakage current is transmitted to the voltage comparison module 33 via the semiconductor active device M4. The reference current generating module 32 preferably uses five semiconductor active devices and one resistor to provide a stable reference current for use by the voltage comparison module 33, wherein the semiconductor active device can be CMOS (complementary metal oxide half field effect) Crystal or general MOSFET (gold oxide half field effect transistor). The reference current generating module 32 generates The reference current is not sensitive to the external supply voltage, the operating temperature, and the process error of the CMOS device, and the aforementioned reference current is transmitted to the voltage comparison module 33 via the semiconductor active device M6. The voltage comparison module 33 uses the current mirror structure formed by the semiconductor active devices M4, M5 to copy the leakage current proportional to the temperature to the semiconductor active device M5 to the semiconductor active device M2 to the capacitor C1 tributary, and charge the capacitor C1. The voltage of its capacitor C1 is Vc. In addition, the current mirror structure formed by the semiconductor active devices M6, M7 is used to copy the temperature-independent reference current to the semiconductor active device M7 to the semiconductor active device M1 to the resistor R1 tributary, and generate a Vref voltage, using the semiconductor active in the figure. The architecture of devices M1, M2 compares voltage Vc with voltage Vref and produces an output in the form of a pulse wave via relaxation oscillator 34. The operation of the flaring oscillator 34 is as follows: when the voltage Vc is greater than the voltage Vref, the voltage Vrst reaches a high voltage to trigger the operation of the semiconductor active device M3 as a switch, so that the capacitor C1 is immediately discharged, and the charge is discharged when the capacitor C1 is discharged. After the completion (when the voltage Vc is lower than the voltage Vref), the voltage Vrst will return to a low voltage and the capacitor C1 will be charged again at a time, thus circulating. The final voltage Vref pulse wave output adjusts the duty cycle of the pulse wave to 50% via the duty cycle adjuster 35 and outputs a frequency to indicate the temperature sensing result.

Please refer to FIG. 5, which is a comparison diagram of the output frequency and temperature of the present invention, wherein the unit of temperature is Celsius (° C.) and the unit of frequency is per second. As shown in Fig. 5, the solid line is the test result of the invention, the broken line is the ideal linear straight line, and the straight line diagram below the figure 5 is the phase difference between the two, we can know that the nonlinearity is 0.94%.

In summary, the temperature sensing device and method of the present invention can easily and accurately measure the temperature, and is easy to implement on the integrated circuit. And the advantages of circuit layout area and power consumption are small.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

I21‧‧‧ leakage current

I22‧‧‧Reference current

Vc, Vref, Vrst‧‧‧ voltage

M1, M2, M4, M5, M6, M7‧‧‧ semiconductor active devices

C1‧‧‧ capacitor

R1‧‧‧ resistance

10‧‧‧ gate

11‧‧‧Oxide

12‧‧‧ source extremes/汲 extremes

13‧‧‧P type substrate

14‧‧‧Back electrode

31‧‧‧Leakage current generation module

32‧‧‧Reference current generation module

33‧‧‧Voltage comparison module

34‧‧‧ Relaxation oscillator

35‧‧‧Work cycle adjuster

36‧‧‧frequency

41‧‧‧Metal oxide semiconductor capacitor

Fig. 1 is a view showing an embodiment of a leakage current generating module of the present invention.

Figure 2 is a block diagram showing the overall system implementation of the present invention.

Figure 3 is a block diagram of the present invention.

Figure 4 is an embodiment of the circuit structure diagram of the present invention.

Figure 5 is a comparison diagram of the output frequency and temperature of the present invention.

Vc, Vref, Vrst‧‧‧ voltage

M1, M2, M4, M5, M6, M7‧‧‧ semiconductor active devices

C1‧‧‧ capacitor

R1‧‧‧ resistance

31‧‧‧Leakage current generation module

32‧‧‧Reference current generation module

33‧‧‧Voltage comparison module

34‧‧‧ Relaxation oscillator

35‧‧‧Work cycle adjuster

41‧‧‧Metal oxide semiconductor capacitor

Claims (9)

A temperature sensing device comprises: a leakage current generating module comprising a metal oxide semiconductor capacitor, wherein the metal oxide semiconductor capacitor operates in a reverse region and generates a leakage current; and a reference current generating module a reference current that does not change with temperature; a voltage comparison module coupled to the leakage current generation module and the reference current generation module, after the reference current and the leakage current are input, after the voltage is generated by the resistor and the capacitor And performing voltage comparison; and a relaxation oscillator coupled to the voltage comparison module to generate a pulse wave output according to the comparison result of the voltage comparison module. The temperature sensing device of claim 1, wherein the voltage comparison module further comprises a first current mirror and a second current mirror, respectively coupled to the leakage current generating module and the reference current generating Module. The temperature sensing device of claim 1, further comprising a duty cycle adjuster coupled to the relaxation oscillator and inputting the pulse waveform output. The temperature sensing device according to claim 1, wherein the leakage current generated by the leakage current generating module is proportional to an absolute temperature. A temperature sensing method is applicable to a circuit, the circuit includes a leakage current generating module, a reference current generating module, a voltage comparison module, and a relaxation oscillator, and the temperature sensing method includes the following steps: using the foregoing voltage Comparing a leakage current generated by the leakage current generating module and a reference current generated by the reference current generating module; and comparing the result of the voltage comparison module, the relaxation oscillator generates a reference current Pulse wave form output. The temperature sensing method according to claim 5, further comprising the steps of: replicating the leakage current and the reference current by using a first current mirror and a second current mirror, respectively. The temperature sensing method according to claim 5, further comprising the step of: adjusting a duty cycle of the pulse wave form output by using a duty cycle adjuster. The temperature sensing method of claim 5, wherein the aforementioned reference current does not vary with temperature. The temperature sensing method according to claim 5, wherein the leakage current generated by the leakage current generating module is proportional to an absolute temperature.