Temperature sensor operating at cryogenic temperatures

Abstract

The present invention relates to a temperature sensor operating at cryogenic temperatures and, more specifically, comprises: a sensing element circuit for converting sensed temperature information into current information; a ring oscillator circuit for receiving the current information from the sensing element circuit and outputting a frequency; and a counter for outputting a digital value corresponding to the sensed temperature information on the basis of the frequency output from the ring oscillator circuit, wherein the sensing element circuit includes: a beta multiplier circuit for generating at least one reference voltage; and a current mirror circuit for generating current information based on the reference voltage and transmitting the current information to the ring oscillator circuit.

Description

Temperature sensors that operate at extremely low temperatures

[0001] The present invention relates to a temperature sensor, and more particularly, to a temperature sensor that operates at extremely low temperatures.

[0002]

[0003] Figure 1 is a circuit diagram illustrating a conventional relaxation oscillator-based temperature sensor.

[0004] Figure 2 is a circuit diagram illustrating a conventional bandgap reference circuit.

[0005] Figure 3 is a frequency-temperature graph of a conventional ring oscillator.

[0006] Referring to Figure 1, a conventional temperature sensor is a temperature sensor based on a relaxation oscillator. Specifically, a conventional temperature sensor converts temperature information into current, which is then used to drive an oscillator, ultimately converting it into frequency information. At this time, a reference voltage is required to drive the comparator. To generate a temperature-independent reference voltage, a bandgap reference circuit is required, as shown in Figure 2, which includes a BJT. The BJT used in this circuit operates from -60°C to 40°C and does not operate in the cryogenic range, making it unsuitable for wideband temperature sensing.

[0007] In addition, looking at the graph shown in Fig. 3, it can be seen that in the case of the existing ring oscillator, the frequency does not show a linear characteristic proportional to the temperature.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] Korean Patent Publication No. 10-2014-0011200 (“Temperature Measuring Circuit”, published on January 28, 2014)

[0011]

[0012] The present invention has been devised to solve the above-mentioned problems, and the purpose of the temperature sensor operating at an extremely low temperature according to the present invention is to provide a temperature sensor capable of measuring temperature even at an extremely low temperature by excluding a bandgap reference circuit including a BJT based on a [start-up]-[beta multiplier]-[current mirror]-[current controlled ring oscillator]-[counter] structure.

[0013]

[0014] In order to solve the above-described problem, a temperature sensor operating at an extremely low temperature according to various embodiments of the present invention includes a sensing element circuit that converts sensed temperature information into current information, a ring oscillator circuit that receives the current information from the sensing element circuit and outputs a frequency, and a counter that outputs a digital value corresponding to the sensed temperature information based on the frequency output from the ring oscillator circuit, wherein the sensing element circuit includes a beta multiplier circuit that generates at least one reference voltage and a current mirror circuit that generates current information based on the reference voltage and transmits the current information to the ring oscillator circuit.

[0015] In addition, the sensing element circuit is characterized by further including a startup circuit that activates the operation of the temperature sensor.

[0016] In addition, the startup circuit is characterized by including a first plurality of transistors, a voltage divider circuit that divides and outputs a power supply voltage, and a second transistor that receives the divided power supply voltage from the voltage divider circuit and activates the operation of the beta multiplier.

[0017] In addition, the beta multiplier circuit is characterized by including a third plurality of transistors that generate at least one reference voltage by a switching operation of the second transistor, and a resistor connected to any one of the third plurality of transistors.

[0018] In addition, the current mirror circuit includes fourth and fifth transistors, each of which has one end connected to the power supply voltage, and sixth and seventh transistors, each of which has one end connected to the other end of the fourth and fifth transistors and has gate terminals connected to each other, wherein the gate terminal of the fourth transistor is connected to the beta multiplier circuit, the gate terminal of the fifth transistor and the other end are connected to each other, and a first voltage is output between the fourth and sixth transistors, and a second voltage is output between the fifth and seventh transistors.

[0019] In addition, the resistance is characterized by satisfying the following formula.

[0020] -formula-

[0021]

[0022] (R is the resistance value at temperature T, is the resistance value at the reference temperature, a is the Temperature coefficient (TC), T is the temperature at which the circuit operates, is the reference temperature at which a is defined)

[0023] In addition, the resistor is characterized by being a rppolywo resistor.

[0024]

[0025] According to the temperature sensor operating at extremely low temperatures according to various embodiments of the present invention as described above, linearity according to the temperature range can be improved and the measurable temperature range can be expanded.

[0026] Additionally, it has the potential to be used in the 4K region of quantum computing systems.

[0027] In addition, it has the effect of improving the operating speed of quantum computing systems.

[0028]

[0029] Figure 1 is a circuit diagram illustrating a conventional relaxation oscillator-based temperature sensor.

[0030] Figure 2 is a circuit diagram illustrating a conventional bandgap reference circuit.

[0031] Figure 3 is a frequency-temperature graph of a conventional ring oscillator.

[0032] Figure 4 is a circuit diagram illustrating a temperature sensor according to an embodiment of the present invention.

[0033] Figure 5 is a sensing element circuit diagram according to an embodiment of the present invention.

[0034] Figure 6 is a ring oscillator circuit diagram according to an embodiment of the present invention.

[0035] Figure 7 is a PTAT current graph according to a sensing element circuit which is an embodiment of the present invention.

[0036] Figure 8 is a graph of CTAT rppolywo resistance according to temperature according to an embodiment of the present invention.

[0037] Figure 9 is a frequency-temperature graph compensated by a sensing element circuit which is an embodiment of the present invention.

[0038] Fig. 10 is a frequency-temperature graph of a current control-based ring oscillator according to an embodiment of the present invention.

[0039]

[0040] In order to explain the present invention, its operational advantages, and the purpose achieved by the practice of the present invention, preferred embodiments of the present invention are exemplified and examined with reference thereto below.

[0041] First, the terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention, and the singular expression may include plural expressions unless the context clearly indicates otherwise. In addition, it should be understood that the terms "comprise" or "have" in this application are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0042] In describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

[0043] Fig. 4 is a circuit diagram illustrating a temperature sensor according to an embodiment of the present invention.

[0044] Fig. 5 is a sensing element circuit diagram according to an embodiment of the present invention.

[0045] Fig. 6 is a ring oscillator circuit diagram according to an embodiment of the present invention.

[0046] As illustrated in FIGS. 4 to 6, a temperature sensor (1000) according to an embodiment of the present invention may include a sensing element circuit (100), a ring oscillator circuit (200), and a counter (300).

[0047] The sensing element circuit (100) can convert sensed temperature information into current information.

[0048] The ring oscillator circuit (200) is connected to the sensing element circuit (100) and can receive current information from the sensing element circuit (100) and output a frequency. At this time, the frequency can be controlled based on the current information obtained from the sensing element circuit (100).

[0049] The counter (300) can output a digital value corresponding to the temperature information sensed by the sensing element circuit (100) based on the frequency output from the ring oscillator circuit (200). At this time, the counter (300) can output 12-bit information corresponding to the temperature information.

[0050] As illustrated in FIG. 5, the sensing element circuit (100) may include a beta multiplier circuit (110) and a current mirror circuit (120) that generate at least one reference voltage.

[0051] The current mirror circuit (120) can generate current information based on the reference voltage generated by the beta multiplier circuit (110) and transmit the generated current information to the ring oscillator circuit (200).

[0052] Meanwhile, as illustrated in FIG. 4, the sensing element circuit (100) according to the present invention may further include a startup circuit (130).

[0053] The startup circuit (130) can be connected to the front end of the beta multiplier circuit (110) to activate the operation of the temperature sensor (1000). That is, the startup circuit (130) can be connected to the front end of the beta multiplier circuit (110) to activate the operation of the beta multiplier circuit (110).

[0054] Specifically, the startup circuit (130) may include a voltage divider circuit and a second transistor.

[0055] The voltage divider circuit includes a first plurality of transistors, through which the power supply voltage can be divided and output. The first plurality of transistors are preferably PMOS and NMOS, and are indicated as MP1 and MN1, respectively.

[0056] The second transistor is connected to the front end of the voltage divider circuit and the beta multiplier circuit (110), and can receive the divided power voltage from the voltage divider circuit and activate the operation of the beta multiplier circuit (110). At this time, the second transistor is preferably NOMS and will be illustrated as MN2.

[0057] Additionally, the beta multiplier circuit (110) may include a third plurality of transistors and resistors (R).

[0058] The third plurality of transistors may include PMOS and NMOS, and specifically, may include MP2, MP3, MN3, and MN4. Through this, at least a reference voltage can be generated by the switching operation of the connected second transistor.

[0059] The resistor (R) can be connected to any one of the third plurality of transistors, specifically, to MN3. More specifically, the current flowing in the beta multiplier circuit (110) can be defined as follows:

[0060]

[0061] Accordingly, resistance (R) can be expressed in a formula as follows:

[0062]

[0063] (R is the resistance value at temperature T, is the resistance value at the reference temperature, a is the Temperature coefficient (TC), T is the temperature at which the circuit operates, is the reference temperature at which a is defined)

[0064] Meanwhile, the current mirror circuit (120) may include fourth and fifth transistors, each having one end connected to a power supply voltage, and sixth and seventh transistors, each having one end connected to the other end of the fourth and fifth transistors and each having gate terminals connected to each other. The fourth and fifth transistors will be illustrated as MP4 and MP5, respectively, and the sixth and seventh transistors will be illustrated as MN5 and MN6, respectively.

[0065] Here, the gate terminal of the fourth transistor may be connected to the beta multiplier circuit (110). In addition, the gate terminal and the other end of the fifth transistor may be connected to each other. In addition, a first voltage may be output between the fourth and sixth transistors, and a second voltage may be output between the fifth and seventh transistors. The first voltage is , and the second voltage is on the drawing. It means.

[0066] In this way, the temperature sensor (1000) according to the present invention includes a beta multiplier circuit (110) in the sensing element circuit (100) to generate a reference voltage, and then, the current mirror circuit (120) class By transmitting current information to the ring oscillator circuit (200) through the circuit, the TC (Temperature coefficient) characteristic of the ring oscillator circuit (200) can be compensated, and since it does not include a BJT for generating a conventional reference voltage, it can operate at extremely low temperatures.

[0067] Figure 7 is a PTAT current graph according to a sensing element circuit which is an embodiment of the present invention.

[0068] Figure 8 is a graph of CTAT rppolywo resistance according to temperature according to an embodiment of the present invention.

[0069] Figure 9 is a frequency-temperature graph compensated by a sensing element circuit which is an embodiment of the present invention.

[0070] Fig. 10 is a frequency-temperature graph of a current-controlled ring oscillator according to an embodiment of the present invention.

[0071] Specifically, induced through the current mirror circuit (120) class The current of the node is proportional to 1 / R according to the above formulas. Therefore, the TC of the current applied to the ring oscillator circuit (200) becomes inversely proportional to the TC of the resistor (R) included in the beta multiplier circuit (110). Therefore, as illustrated in FIG. 7, the resistor (R) included in the beta multiplier circuit (110) to create a linear PTAT current may be a CTAT (complementary to absolute temperature) resistor, as illustrated in FIG. 8. More specifically, it may be a rppolywo resistor supported by the TSMC 65nm process.

[0072] Accordingly, the frequency-temperature graph compensated through the sensing element circuit (100) of the present invention may be as shown in Fig. 9. At this time, the TC of the frequency can be controlled through the TC of the current generated through the sensing element circuit (100), and accordingly, as shown in Fig. 10, the ring oscillator circuit (200) can be controlled to have high linearity in a wide range from 4K to 300K.

[0073] While preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, those skilled in the art to which the present invention pertains may make numerous changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications should be considered equivalents and fall within the scope of the present invention.

Claims

1. A sensing element circuit that converts sensed temperature information into current information; A ring oscillator circuit that receives current information from the sensing element circuit and outputs a frequency; and A counter that outputs a digital value corresponding to the sensed temperature information based on the frequency output from the ring oscillator circuit; The above sensing element circuit, A beta multiplier circuit that generates at least one reference voltage; and A temperature sensor comprising a current mirror circuit that generates current information based on the reference voltage and transmits the current information to the ring oscillator circuit.

2. In paragraph 1, The above sensing element circuit, A temperature sensor further comprising a startup circuit that activates the operation of the temperature sensor.

3. In paragraph 2, The above startup circuit is, A voltage divider circuit including a first plurality of transistors and dividing and outputting a power supply voltage; and A temperature sensor comprising a second transistor that receives the divided power voltage from the divided circuit and activates the operation of the beta multiplier.

4. In paragraph 3, The above beta multiplier circuit, A third plurality of transistors that generate at least one reference voltage by the switching operation of the second transistor; and A temperature sensor comprising a resistor connected to any one of the third plurality of transistors.

5. In paragraph 3, The above current mirror circuit, First, the fourth and fifth transistors are each connected to the power supply voltage; and The other terminals and one terminal of the fourth and fifth transistors are respectively connected, and the sixth and seventh transistors have gate terminals connected to each other; The gate terminal of the fourth transistor is connected to the beta multiplier circuit, The gate terminal and the other terminal of the fifth transistor are connected to each other, A first voltage is output between the fourth and sixth transistors, A temperature sensor in which a second voltage is output between the fifth and seventh transistors.

6. In paragraph 4, The above resistance is a temperature sensor that satisfies the following formula. -formula- (R is the resistance value at temperature T, is the resistance value at the reference temperature, a is the Temperature coefficient (TC), T is the temperature at which the circuit operates, is the reference temperature at which a is defined) 7. In paragraph 6, The above resistor is a temperature sensor, which is a rppolywo resistor.

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