KR102409226B1 - Bandgap reference voltage circuit - Google Patents

Abstract

The embodiment disclosed herein is a reference voltage supply included in an electronic device used in a radiation environment, a first circuit unit receiving a first input voltage from an external power supply source and outputting a first output voltage, and A second circuit unit that receives a second input voltage different from the first input voltage and outputs a second output voltage different from the first output voltage, stabilizing each of the first output voltage and the second output voltage a buffer unit and a subtraction unit receiving the first output voltage and the second output voltage from the buffer unit, amplifying a difference between the first output voltage and the second output voltage, and outputting a reference voltage, wherein The first circuit unit and the second circuit unit relate to a reference voltage supply having a variation width of an output voltage within a predetermined range at the same temperature.

Description

Reference Voltage Supply {BANDGAP REFERENCE VOLTAGE CIRCUIT}

This specification relates to a reference voltage supply included in an electronic device used in a radiation environment.

Semiconductor devices such as BJT and CMOS have a characteristic that device characteristics change according to temperature. A circuit used to always supply a constant voltage regardless of the temperature characteristics of the semiconductor device is called a reference voltage supply. The reference voltage supply is used in various analog circuits such as analog-to-digital converters, digital-to-analog converters, temperature sensors, and voltage regulators. A general reference voltage supply is configured as shown in FIG. 1 .

The circuit composed of PM1, PM2, NM1, and NM2 is a circuit that supplies a constant current and returns to the original current by the connected nodes even when the supply voltage fluctuates. The generated current is defined by NM1, NM2, and R1, and this current has a characteristic that changes in proportion to the temperature.

[Equation 1]

The current that increases with this temperature is called Proportional to Absolute Temperature current (PTAT current). The PTAT current flows through R ₂ through the PM3 current mirror. NM3, NM4, and NM5 are CMOS diode connections and operate the same as diodes. At this time, the voltage acting on the diode is inversely proportional to the temperature. This is called Complementary to Absolute Temperature voltage (CTAT voltage). When the output voltage is calculated using this, it is expressed as in [Equation 2], and by substituting the [Equation 1] above, the output voltage can be finally expressed as the following [Equation 3]. Since the following [Equation 3] is expressed as the sum of the CTAT voltage (V _CTAT ) and the PTAT voltage (V _PTAT ), a constant voltage flows regardless of the temperature.

[Equation 2]

[Equation 3]

In the radiation environment, the output voltage fluctuation occurs in the reference voltage supply as shown in FIG. 2B. In general, two effects occur when semiconductor devices are exposed to radiation. Single Event Effect (SEE) is a temporary error that inverts bits of digital circuitry such as D Flip Flop (DFF) and Static Random Access Memory (SRAM). Another effect is the Total Ionization Effect (TID), which causes cumulative damage to semiconductor devices. As shown in Figure 3, when radiation is irradiated to the semiconductor device, electron-hole pairs are created in the MOSFET oxide layer. The generated electron-hole pairs are rapidly annihilated by recombination or tunneling effects. However, holes that are relatively slow compared to electrons are trapped in the oxide layer and affect the electrical field of the channel. This causes a threshold voltage shift. In addition, a parasitic channel is formed by the hole trapped in Shallow Trench Isolation (STI), and leakage current increases. In the case of a bandgap reference circuit, a few to several tens of mV output voltage fluctuation occurs when irradiated with radiation.

In the case of the previous radiation hardened bandgap reference circuit, an Enclosed Layout Transistor (ELT) was used to minimize the radiation effect. However, there are disadvantages such as difficulty in design and simulation using the ELT structure and the need for a large area. Therefore, errors due to accumulated damage still exist.

This specification is intended to provide an embodiment of a reference voltage supply that can improve the limitations of the prior art.

That is, the present specification is intended to provide an embodiment of a reference voltage supply capable of removing a voltage error caused by radiation.

Another object of the present invention is to provide an embodiment of a reference voltage supply capable of stably and accurately outputting a reference voltage by reducing an output error of the reference voltage.

An embodiment of the reference voltage supply for solving the above-described problems, in the reference voltage supply included in an electronic device used in a radiation environment, receives a first input voltage from an external power source to generate a first output voltage A first circuit unit for outputting, a second circuit unit receiving a second input voltage different from the first input voltage from the power supply and outputting a second output voltage different from the first output voltage, the first Receives the first output voltage and the second output voltage from the buffer unit and the buffer unit for stabilizing the output voltage and the second output voltage, respectively, and amplifies the difference between the first output voltage and the second output voltage and a subtraction unit for outputting a reference voltage, wherein the first circuit unit and the second circuit unit have variations in output voltage within a predetermined range at the same temperature.

In an embodiment, the radiation environment may be an environment corresponding to a predetermined exposure standard or more.

In an embodiment, the exposure criterion may be a reference for a total radiation exposure amount or an hourly radiation exposure amount during exposure to the radiation environment.

In an embodiment, the exposure standard may be a reference for a maximum radiation exposure amount during exposure to the radiation environment.

In an embodiment, the power supply source may include a first supply source for applying the first input voltage to the first circuit unit and a second supply source for applying the second input voltage to the second circuit unit.

In an embodiment, the power supply is configured to generate each of the first input voltage and the second input voltage such that a difference in magnitude between the first input voltage and the second input voltage falls within a preset reference range, It may be applied to each of the circuit unit and the second circuit unit.

In an embodiment, the first circuit unit and the second circuit unit may be complementary metal-oxide semicondoctors (CMOS).

In an embodiment, the first circuit unit and the second circuit unit may have the same size.

In an embodiment, the first circuit unit and the second circuit unit may be manufactured by the same process.

In an embodiment, the first circuit unit and the second circuit unit may have the same temperature characteristics.

The reference voltage supply disclosed herein outputs a result of subtracting two voltages applied to a differential input as a reference voltage, thereby eliminating a common component caused by radiation effects.

In addition, the reference voltage supply disclosed herein supplies a reference voltage through a differential input and its subtraction, thereby compensating for the effect of radiation on the entire circuit.

1 is an exemplary diagram showing a circuit configuration of a conventional reference voltage supply.
Figure 2a is a graph showing the change in the output voltage according to the temperature of the conventional reference voltage supply.
Figure 2b is a graph showing a change in the output voltage according to the radiation dose of the conventional reference voltage supply.
3A is a conceptual diagram schematically illustrating the effect of total ionization dose of a typical MOSFET.
3B is a structural diagram showing the basic structure of a general MOSFET.
4 is a block diagram showing the configuration of a reference voltage supply according to the embodiment.
5A is a conceptual diagram illustrating a reference voltage output principle of a reference voltage supply according to an embodiment a.
5B is a conceptual diagram illustrating a reference voltage output principle of a reference voltage supply according to an embodiment b.
5C is a conceptual diagram illustrating a reference voltage output principle of a reference voltage supply according to an embodiment c.
6 is a graph showing a characteristic curve of a circuit part of a reference voltage supply according to an embodiment.
Figure 7a is a graph showing the irradiation test results of the general reference voltage supply and the reference voltage supply according to the embodiment.
7B is a graph showing a temperature change test result of a general reference voltage supply and a reference voltage supply according to an embodiment;
Figure 8a is an exemplary view showing a specific application example of the reference voltage supply according to the embodiment.
8B is a graph showing a change in output voltage according to the specific application example shown in FIG. 8A.

Hereinafter, embodiments of a circuit breaker and its signal detection circuit according to the present invention will be described with reference to the accompanying drawings, but the same or similar components are assigned the same reference numbers regardless of reference numerals, and overlapping descriptions thereof will be omitted. decide to do

In addition, in describing the technology disclosed in the present specification, if it is determined that a detailed description of a related known technology may obscure the gist of the technology disclosed in this specification, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easy understanding of the spirit of the technology disclosed in this specification, and should not be construed as limiting the spirit of the technology by the accompanying drawings.

The reference voltage supply (hereinafter, referred to as a supply) disclosed in the present specification may be a circuit device that supplies a voltage of a certain magnitude.

Here, the circuit device may refer to a device including one or more circuit elements or a device in which functions of one or more circuit elements are integrated.

For example, it may be an IC device, or a circuit module including the same.

The feeder may be a device used in a plurality of electronic devices or electronic devices including electronic circuits.

For example, at least one analog circuit may be included in an analog circuit such as an analog-to-digital converter, a digital-to-analog converter, a temperature sensor, or a voltage regulator.

The feeder may in particular be a feeder incorporated in an electronic device used in a radiation environment.

That is, the supply may be a reference voltage supply included in an electronic device used in a radiation environment.

Such a configuration according to the embodiment of the feeder 100 may be as shown in FIG. 4 .

As shown in FIG. 4, the supply 100 receives a first input voltage Vin1 from an external power supply 10 and outputs a first output voltage Vref1. A first circuit unit 110, Receives a second input voltage Vin2 of a different magnitude from the first input voltage Vin1 from the power supply 10 and generates a second output voltage Vref2 of a different magnitude from the first output voltage Vref1 A second circuit unit 120 for outputting, a buffer unit 130 stabilizing each of the first output voltage Vref1 and the second output voltage Vref2, and the first output voltage Vref1 from the buffer unit 130 ) and the second output voltage Vref2, the subtractor 140 amplifies the difference between the first output voltage Vref1 and the second output voltage Vref2 to output a reference voltage VREF. include

Here, the radiation environment may be an environment corresponding to a predetermined exposure standard or more.

That is, the supply 100 may be included in an electronic device used in a radiation environment corresponding to the exposure standard or higher.

Accordingly, the supplier 100 may be exposed to radiation in a radiation environment higher than the exposure standard, and may be affected by the radiation.

The exposure standard may be a reference for a total radiation exposure amount or an hourly radiation exposure amount during exposure to the radiation environment.

For example, when the total radiation exposure amount is 20 [kGY] during 20 [h] of exposure to the radiation environment, the exposure standard may be 20 [kGY] or 1 [kGY/h].

When the exposure standard is such, the electronic device including the supply 100 is used in a radiation environment where the total radiation exposure is 20 [kGY], or in a radiation environment where the radiation exposure per hour is 1 [kGY/h], Accordingly, the feeder 100 may be exposed to radiation in a radiation environment corresponding to the exposure standard.

The exposure criterion may also be a criterion for a maximum radiation exposure amount during exposure to the radiation environment.

For example, when the maximum radiation exposure amount during exposure to the radiation environment is 2 [kGY], the exposure standard may be 2 [kGYMAX].

The power supply 10 may be a circuit element or device for supplying an input voltage, which is a basis for the supply 100 to output the reference voltage, to the supply 100 .

The power supply 10 may supply an input voltage to each of the first circuit unit 110 and the second circuit unit 120 .

The power supply 10 may supply the first input voltage Vin1 to the first circuit unit 110 and the second input voltage Vin2 to the second circuit unit 120 in different sizes. .

That is, the power supply 10 supplies the first circuit unit 110 and the second circuit unit 120 with different levels of the first input voltage Vin1 and the second input voltage Vin2 , respectively. can be done

The power supply 10 includes a first supply source 11 for applying the first input voltage Vin1 to the first circuit unit 110 and the second input voltage Vin2 to the second circuit unit 120 . It may include a second source 12 for applying the.

That is, the power supply 10 increases each of the first input voltage Vin1 and the second input voltage Vin2 through each of the first supply source 11 and the second supply source 12 . Alternatively, it may be supplied to each of the first circuit unit 110 and the second circuit unit 120 .

The power supply 10 may include the first input voltage Vin1 and the second input voltage Vin1 and the second input voltage such that a difference in magnitude between the first input voltage Vin1 and the second input voltage Vin2 falls within a preset reference range. Each of (Vin2) may be generated and applied to each of the first circuit unit 110 and the second circuit unit 120 .

For example, when the reference range is set to 5 [V], the power supply 10 is configured such that the difference in the magnitude of the first input voltage Vin1 and the second input voltage Vin2 is within 5 [V]. Each of the first input voltage Vin1 and the second input voltage Vin2 may be generated and applied to each of the first circuit unit 110 and the second circuit unit 120 .

Accordingly, the first circuit unit 110 and the second circuit unit 120 may receive input voltages of different magnitudes from each other.

As such, in the supply 100 that receives input voltages of different magnitudes from the power supply source 10 and outputs the reference voltage, the first circuit unit 110 and the second circuit unit 120 output at the same temperature. The voltage fluctuation range falls within a certain range.

More specifically, when different input voltages are applied to the first circuit unit 110 and the second circuit unit 120 in the same temperature environment, the output voltages may differ only within the predetermined range.

That is, when the supply 100 receives different input voltages at the same temperature, the output voltage of the first circuit unit 110 and the output voltage of the second circuit unit 120 vary within the predetermined range. It can be changed only by the width.

For example, when the predetermined range is ±0.1 [V], when different voltages are applied to each of the first circuit unit 110 and the second circuit unit 120 at X [°C], the first circuit unit 110 A difference between the first output voltage Vref1 output from ) and the second output voltage Vref2 output from the second circuit unit 120 may be ±0.1 [V].

Accordingly, when input voltages of different magnitudes are applied at the same temperature, the difference between the first output voltage Vref1 and the second output voltage Vref2 output from the second circuit unit 120 is at most 0.1 [V] ] can be within

Meanwhile, when the same input voltage is applied to the first circuit unit 110 and the second circuit unit 120 in the same temperature environment, the magnitude of the output voltage may be the same.

That is, the supply 100, when the same input voltage is applied at the same temperature, the output voltage of the first circuit unit 110 and the output voltage of the second circuit unit 120 may be output with the same magnitude.

Each of the first circuit unit 110 and the second circuit unit 120 may be a reference voltage supply circuit that outputs a constant voltage according to an input voltage.

That is, the supply 100 may include two reference voltage supply circuits.

The first circuit unit 110 and the second circuit unit 120 may be complementary metal-oxide semicondoctors (CMOS).

The CMOS may refer to a semiconductor device in which a plurality of MOSFETs are integrated.

The first circuit unit 110 and the second circuit unit 120 may have the same size.

The CMOS has different effects of radiation depending on the size of the width and length. When the first circuit part 110 and the second circuit part 120 made of the CMOS have the same size, the radiation effect is the same, so that the same voltage fluctuation is can be done

That is, the first circuit unit 110 and the second circuit unit 120 may have the same size, so that the voltage fluctuation characteristic may fall within the predetermined range.

The first circuit unit 110 and the second circuit unit 120 may be manufactured by the same process.

That is, the first circuit unit 110 and the second circuit unit 120 may be CMOS devices designed to have the same value.

The first circuit unit 110 and the second circuit unit 120 may have the same temperature characteristics.

Accordingly, when the first circuit unit 110 and the second circuit unit 120 receive the same input voltage at the same temperature, the first output voltage Vref1 and the second output voltage Vref2 are It may be changed only by a corresponding fluctuation width within a certain range, and preferably, the magnitude of the output voltage may be the same.

In addition, since the temperature characteristics of the first circuit unit 110 and the second circuit unit 120 are the same, the first circuit unit 110 and the second circuit unit 120 receive different input voltages at the same temperature. Even in this case, the first output voltage Vref1 and the second output voltage Vref2 may vary only by a variation width corresponding to the predetermined range.

The first circuit part 110 and the second circuit part 120 receive the first input voltage Vin1 and the second input voltage Vin2 of different magnitudes, and the first output of different magnitudes Each of the voltage Vref1 and the second output voltage Vref2 may be output to the buffer unit 130 .

That is, since voltage levels of the first input voltage Vin1 and the second input voltage Vin2 are differently applied to the first circuit unit 110 and the second circuit unit 120 , respectively, the first circuit unit 110 ) and the levels of the first output voltage Vref1 and the second output voltage Vref2 output from each of the second circuit unit 120 may be different from each other.

The buffer unit 130 receives and stabilizes the first output voltage Vref1 and the second output voltage Vref2 from each of the first circuit unit 110 and the second circuit unit 120 , and the subtraction It may be a buffer that is transferred to the unit 140 .

The buffer unit 130 stabilizes the first voltage buffer 131 and transmits the first output voltage Vref1 to the subtraction unit 140 by stabilizing the second output voltage Vref2 to provide the subtraction unit It may include a second voltage buffer 132 that transfers to 140 .

Accordingly, the buffer unit 130 may accurately stabilize each of the first output voltage Vref1 and the second output voltage Vref2 having different sizes according to the voltage level.

The subtraction unit 140 receives the first output voltage Vref1 and the second output voltage Vref2 stabilized by the buffer unit 130 , and receives the first output voltage Vref1 and the second output voltage Vref2. It may be an operational amplifier (OP Amp) circuit that amplifies the difference between the output voltages Vref2 and outputs the reference voltage VREF.

As such, the subtractor 140 amplifies the difference between the first output voltage Vref1 and the second output voltage Vref2 to output the reference voltage VREF, so that the first output voltage Vref1 and the second output voltage Vref2 are output. The reference voltage in which the same variation included in each of the second output voltages Vref2 is canceled may be output.

The first circuit unit 110 , the second circuit unit 120 , the buffer unit 130 , and the subtraction unit 140 . When explaining the specific output principle and embodiment of the reference voltage of the supply unit 100 , As follows.

As shown in FIG. 5A , the final reference voltage of the supply 100 having the same characteristics with respect to temperature and having two voltage differences having different magnitudes as a reference voltage is the following [Equation 3] can be expressed as

[Equation 3]

과

변동이 발생하므로, 상기 [수학식 3]은 하기 [수학식 4]와 같이 나타낼 수 있다.When the feeder 100 is placed in a radiation environment

class

Since the fluctuation occurs, the [Equation 3] can be expressed as the following [Equation 4].

[Equation 4]

[Equation 4] can be expressed again by the following [Equation 5].

[Equation 5]

), 도 5c에 도시된 바와 같이 상기 [수학식 5]를 하기 [수학식 6]으로 나타낼 수 있다.When the feeder 100 is the same as shown in FIG. 5B, the fluctuation due to radiation (

), as shown in FIG. 5c , the [Equation 5] can be expressed as the following [Equation 6].

[Equation 6]

According to the characteristics of the supply 100, the MOSFET should operate in a saturation region, and the operating point of the MOSFET device in the saturation region may be defined as in Equation 7 below.

[Equation 7]

At this time, as the drain voltage increases, the pinch-off of the channel increases and the length of the channel decreases. Since the drain current has a characteristic inversely proportional to the length of the channel, a decrease in the channel length causes an increase in the current as shown in FIG. 6 . This is called the channel length modulation effect. By using this characteristic, it is possible to create a current difference by varying the input voltages of the first circuit unit 110 and the second circuit unit 120 .

The first output voltage Vref1 and the second output voltage Vref2 output from the first circuit unit 110 and the second circuit unit 120 pass through the buffer unit 130 to the subtraction unit 140 . is input to, and the difference between the first output voltage Vref1 and the second output voltage Vref2 may be output through the subtraction unit 140 including an operational amplifier.

In this case, the output from the subtractor 140 may be the reference voltage VREF.

The reference voltage VREF may be expressed as a resistance ratio as shown in Equation 7 below.

[Equation 7]

As described above, if the resistance is adjusted after determining the difference between the two circuits, a desired reference voltage may be output.

As described above, the common component of the two voltages applied to the differential input may be removed.

Accordingly, a common component of the voltage supplied from the first circuit unit 110 and the second circuit unit 120 is canceled, and accordingly, a radiation error may be completely eliminated.

The effect of improving the radiation error of the feeder 100 will be described as follows.

7A is a graph showing the irradiation test results of a general reference voltage supply and a reference voltage supply according to the embodiment, and using a Co-60 source emitting gamma rays of 1.33 [MeV] and 1.17 [MeV], the circuit is This is the result of checking how much the output voltage changes when irradiated with radiation at a rate of 1 [kGy/h] (total irradiation dose 20 [kGy]) for 20 hours after placing it in front.

7b is a graph showing the temperature change test results of a general reference voltage supply and a reference voltage supply according to an embodiment. This is the result of checking how much the output voltage changes when the furnace temperature is increased.

As shown in Figure 7a, in the case of the irradiation test, the supply 100 shows a 60% superior stability on average compared to the conventional standard voltage supply, the maximum variation also showed a 43% reduction.

As shown in FIG. 7B , in the case of the temperature experiment, the general structure of the reference voltage supply increased by 26 [mV], whereas the supply 100 according to the embodiment changed only 0.26 [mV].

That is, the performance of the supply 100 was improved by about 90% compared to the conventional general reference voltage supply.

The supply 100 as such is applied to nuclear power plant CCTV, nuclear accident robots, and electronic equipment such as nuclear inspection and aerospace systems, and can supply a reference voltage of a certain size regardless of radiation effects.

For a specific application, it may be used as a cold junction compensation circuit of a thermocouple temperature measuring device as shown in FIG. 8A .

Thermocouple temperature measuring equipment is a device used to measure the temperature inside a nuclear power plant, which is a radiation environment, and there is a problem that the temperature error increases as the error of the reference voltage supply increases due to the effect of radiation.

A result of using the feeder 100 as a cold junction compensation circuit in such a temperature measuring device is shown in FIG. 8B .

8B is a graph comparing the change in the output voltage of the reference voltage supply and the change in the output voltage of the thermocouple according to the temperature. The output voltage of the reference voltage supply is constant, while the thermocouple output voltage increases linearly with the temperature. , it is possible to accurately predict the temperature by measuring it.

Accordingly, it is possible to increase the reliability of the thermocouple temperature measuring equipment used in the radiation environment.

Preferred embodiments of the present invention described above are disclosed in order to solve the technical problems, and those skilled in the art to which the present invention pertains may make various modifications, changes, additions, etc. within the spirit and scope of the present invention. This will be possible, and such modifications should be considered as belonging to the following claims.

100: reference voltage supply
110: first circuit unit 120: second circuit unit
130: buffer unit 140: subtractor

Claims (10)

A reference voltage supply included in an electronic device used in a radiation environment, comprising:
a first circuit unit receiving a first input voltage from an external power source and outputting a first output voltage;
a second circuit unit receiving a second input voltage different from the first input voltage from the power supply and outputting a second output voltage different from the first output voltage;
a buffer unit for stabilizing each of the first output voltage and the second output voltage; and
a subtraction unit receiving the first output voltage and the second output voltage from the buffer unit, amplifying a difference between the first output voltage and the second output voltage, and outputting a reference voltage; and
The first circuit unit and the second circuit unit,
A reference voltage supply, characterized in that the fluctuation range of the output voltage at the same temperature falls within a certain range. According to claim 1,
The radiation environment is
Reference voltage supply, characterized in that the environment corresponding to a certain exposure standard or more. 3. The method of claim 2,
The exposure standard is
and a reference voltage supply for total radiation exposure or hourly radiation exposure during exposure to the radiation environment. 3. The method of claim 2,
The exposure standard is
A reference voltage supply as a reference for a maximum radiation exposure during exposure to the radiation environment. According to claim 1,
The power supply is
a first supply source for applying the first input voltage to the first circuit unit; and
and a second supply source for applying the second input voltage to the second circuit unit. According to claim 1,
The power supply is
The first input voltage and the second input voltage are respectively generated so that a difference in magnitude between the first input voltage and the second input voltage falls within a preset reference range, and applied to the first circuit unit and the second circuit unit, respectively A reference voltage supply, characterized in that. According to claim 1,
The first circuit unit and the second circuit unit,
A reference voltage supply characterized in that it is a complementary metal-oxide semicondoctor (CMOS). 8. The method of claim 7,
The first circuit unit and the second circuit unit,
Reference voltage supply, characterized in that made of the same size. 8. The method of claim 7,
The first circuit unit and the second circuit unit,
Reference voltage supply, characterized in that manufactured by the same process. 8. The method of claim 7,
The first circuit unit and the second circuit unit,
A reference voltage supply characterized in that the temperature characteristics are the same.

Images