CN117120955A

CN117120955A - Compensation of thermally induced voltage errors

Info

Publication number: CN117120955A
Application number: CN202280027684.7A
Authority: CN
Inventors: S·S·克里希南; A·Y·贾达夫; T·维什瓦纳特
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 2021-04-12
Filing date: 2022-04-11
Publication date: 2023-11-24

Abstract

The described embodiments include an integrated circuit (200) for temperature gradient compensation of bandgap voltages. The bandgap core circuit (220) has a bandgap feedback input, a bandgap adjustment input, and a bandgap reference output. A resistor (224) is coupled between the bandgap adjusted input and the ground terminal. An offset and slope correction circuit (210) has an offset correction output coupled to the bandgap adjustment input. A Thermal Error Cancellation (TEC) circuit has a TEC output coupled to a bandgap adjustment input. The TEC circuit (230) includes a first temperature sensor and a second temperature sensor located remotely from each other. The signal at the TEC output (232) is responsive to temperatures at the first temperature sensor and the second temperature sensor. An amplifier (240) has an amplifier input and an amplifier output. The amplifier input is coupled to the bandgap reference output.

Description

Compensation of thermally induced voltage errors

Background

The present description relates to voltage references and thermal gradients within voltage regulator circuits. Different regions within an integrated circuit may be at different temperatures due to internal thermal heating. The temperature differences are caused by different amounts of power dissipation in the component from different regions of the integrated circuit. The temperature differences within the integrated circuit create thermal gradients that result in errors in the output voltage or reference voltage.

Line regulation (line regulation) and load regulation are important specifications to be met by voltage references and voltage regulators. However, line regulation and load regulation may be adversely affected by thermal gradients created when the output buffer amplifier dissipates heat. Voltage regulators and voltage references are intended to provide a constant output voltage independent of supply voltage or load current, but the output voltage may be subject to errors. These errors in the output voltage may be caused at least in part by thermal gradients.

The magnitude of the voltage error increases as the thermal gradient across the integrated circuit increases. It is desirable to sense and minimize errors caused by thermal gradients across the integrated circuit. Preferably, the present solution will have low electrical noise, occupy minimal area and consume minimal quiescent current.

Disclosure of Invention

In a first example, an integrated circuit for temperature gradient compensation of a bandgap voltage includes a bandgap core circuit. The bandgap core circuit has a bandgap feedback input, a bandgap adjustment input, and a bandgap reference output. A resistor is coupled between the bandgap adjustment input and ground. The offset and slope correction circuit has an offset correction output coupled to the bandgap adjustment input. The signal at the offset correction is trimmed (trimmed) at ambient temperature.

A Thermal Error Cancellation (TEC) circuit has a TEC output coupled to a bandgap adjustment input. The TEC circuit includes a first temperature sensor and a second temperature sensor located remotely from each other. The signal at the TEC output is responsive to the temperatures at the first temperature sensor and the second temperature sensor. The amplifier has an amplifier input and an amplifier output. The amplifier input is coupled to the bandgap reference output.

In a second example, an integrated circuit for temperature gradient compensation of a bandgap voltage includes a bandgap reference circuit having a bandgap adjustment input and a bandgap reference output. The first transistor is at a first location. The first transistor has a first transistor current terminal and a second transistor current terminal and a first control terminal. The second transistor current terminal is coupled to ground through a first resistor. The second transistor is at a second location. The second transistor has a third transistor current terminal and a fourth transistor current terminal and a second control terminal. The second control terminal is coupled to the first control terminal, and the fourth transistor current terminal is coupled to ground through a second resistor.

The third transistor is at a second location. The third transistor has a fifth transistor current terminal and a sixth transistor current terminal and a third control terminal. The sixth transistor current terminal is coupled to ground through a resistor. The fourth transistor is at the first location. The fourth transistor has a seventh transistor current terminal and an eighth transistor current terminal and a fourth control terminal. The fourth control terminal is coupled to the third control terminal, and the fourth transistor current terminal is coupled to ground through a resistor.

The fifth transistor is coupled between the bandgap reference output and the first control terminal and has a fifth control terminal coupled to the first transistor current terminal. The sixth transistor has a ninth transistor current terminal and a tenth transistor current terminal and a sixth control terminal. The sixth control terminal is coupled to the fifth control terminal and the tenth transistor current terminal is coupled to the third transistor current terminal. The seventh transistor is coupled between the bandgap reference output and the third control terminal. The seventh transistor has a seventh control terminal coupled to the fifth transistor current terminal.

The eighth transistor has an eleventh transistor current terminal and a twelfth transistor current terminal, and an eighth control terminal. The eighth control terminal is coupled to the seventh control terminal and the twelfth transistor current terminal is coupled to the seventh transistor current terminal. The amplifier has an amplifier input and an amplifier output. An amplifier input is coupled to the eleventh transistor current terminal and an amplifier output is configured to provide a signal proportional to a temperature difference between the first location and the second location.

In a third example, a temperature sensor circuit includes a first transistor at a first location. The first transistor has a first transistor current terminal and a second transistor current terminal and a first control terminal. The first transistor current terminal is coupled to the first control terminal and the second transistor current terminal is coupled to ground through a first resistor. The first transistor current terminal provides a first temperature signal in response to a temperature at a first location.

The second transistor is located at a second location. The second transistor has a third transistor current terminal and a fourth transistor current terminal and a second control terminal. The second control terminal is coupled to the first control terminal, and the fourth transistor current terminal is coupled to ground through a second resistor. The third transistor is located at the second position. The third transistor has a fifth transistor current terminal and a sixth transistor current terminal and a third control terminal. The third control terminal is coupled to the fifth transistor current terminal and the sixth transistor current terminal is coupled to ground through a third resistor. The fifth transistor current terminal provides a second temperature signal in response to the temperature at the second location.

The fourth transistor is located at the first position. The fourth transistor has a seventh transistor current terminal and an eighth transistor current terminal and a fourth control terminal. The fourth control terminal is coupled to the third control terminal, and the fourth transistor current terminal is coupled to ground through a fourth resistor.

Drawings

FIG. 1 illustrates a thermal gradient diagram of an example voltage reference integrated circuit.

Fig. 2 shows a block diagram for an example thermoelectric cancellation circuit.

FIG. 3 shows a schematic diagram for an example temperature sensor that provides a high-precision, low-noise signal representative of a temperature difference between two points in a circuit.

FIG. 4 shows a schematic diagram for an example bandgap reference circuit having temperature sensors at two locations in the circuit and having thermal error compensation.

Fig. 5 shows a flow chart of a method for determining a thermal error cancellation code.

Detailed Description

In this specification, the same reference numerals describe the same or similar (functionally and/or structurally) features. The figures are not necessarily drawn to scale.

Within an integrated circuit, different regions may be at different temperatures due to uneven heat distribution from a single source (such as a power amplifier or buffer amplifier) that dissipates a relatively high amount of power. The heat generated by the power dissipation will be highest near the amplifier and proportionally reduced away from the amplifier. This creates a thermal gradient across the integrated circuit. These thermal gradients can cause output voltage errors.

Fig. 1 illustrates a thermal gradient diagram of an example voltage reference integrated circuit 100. Buffer amplifier 110 is positioned near one end of integrated circuit 100. The first bandgap core circuit 112 is positioned adjacent to the buffer amplifier 110 opposite the one end. The second bandgap core circuit 114 is positioned adjacent to the first bandgap core circuit 112 on a side remote from the buffer amplifier 110. The transistor array 116 is positioned adjacent to the second bandgap core circuit 114 on a side remote from the buffer amplifier 110. Trimming circuitry 118 (which may include circuitry for performing dual temperature trimming) is positioned adjacent to transistor array 116 on a side remote from buffer amplifier 110.

The thermal gradient map has isothermal zones 120-170, where each successively higher numbered isothermal zone represents a higher temperature. For example, region 122 represents a higher temperature than region 120, and region 130 represents a higher temperature than region 120 or region 122. Isothermal region 170 represents the highest temperature on integrated circuit 100.

The isothermal region 170, representing the highest temperature, is centered around the buffer amplifier 110 because the buffer amplifier 110 has the highest power consumption on the integrated circuit 100 and is therefore the hottest location on the integrated circuit 100. The region progressively closer to the buffer amplifier 110 will progressively warm and the region progressively farther from the buffer will become proportionally cooler. If the bandgap core circuitry (i.e., 112, 114) covers a relatively large area of the integrated circuit, certain components in the circuit will heat to a higher temperature than components in other sections of the circuit, creating a thermal gradient within the circuit.

Two factors that affect the severity of the temperature gradient are the spatial size of the bandgap circuit and the amount of power dissipated in the buffer amplifier. The temperature gradient is 1/r ² And a change, where r is the distance from the buffer. The temperature gradient increases linearly with respect to the buffer amplifier power dissipation. Thus, there are first and second order effects that contribute to the error caused by the temperature gradient.

One possible solution for minimizing the errors caused by the temperature gradients is to make the thermal gradients as uniform as possible throughout the integrated circuit. For example, instead of placing the buffer amplifier near one edge, the buffer amplifier is placed near both edges by splitting the amplifier circuit. If the buffer amplifier is on both edges, the temperature gradient may be more uniform. However, the uniformity achievable by the temperature gradient is theoretically limited, since the temperature closer to the buffer amplifier will always be higher and the temperature farther from the buffer amplifier will always be lower unless the entire heating source resides throughout the entire integrated circuit. Therefore, it is impractical to eliminate voltage errors caused by temperature gradients only by the integrated circuit layout. The use of integrated circuit layouts can only reduce the voltage error to a certain level. In addition, this approach brings about a significant and undesirable increase in area.

A second possible solution for minimizing the errors caused by the temperature gradients is to electrically eliminate the errors created by the thermal gradients. The voltage error is created by the buffer amplifier driving current, which dissipates power and the power is converted to heat. Heat propagates through the integrated circuit and as the buffer amplifier is further away, dissipation is proportional to the square of the distance, creating a temperature gradient across the integrated circuit. The temperature gradient creates a voltage error signal. By sensing the current in the buffer, a measure of the expected heat in the circuit can be derived. A second current proportional to the first current and having an opposite sign may be generated to compensate for the error current.

The compensation signal may be generated by a current in a buffer amplifier and then applied to the bandgap core in the opposite direction. However, sensing only the current in the buffer amplifier is not sufficient, as the heating is caused by power dissipation and not just the current. To fully compensate for the errors, it is necessary to sense the current and voltage and convert it to power, and this power is used to estimate the circuit heating. This requires a multiplier circuit because the power is proportional to the product of voltage and current. The circuitry that processes the voltage and current and performs this multiplication may add too much additional noise to meet the important specifications for high precision low noise applications. Thus, alternative solutions are needed.

The measurement is thermoelectrically cancelled and then the error source is replicated to more closely track the error mechanism and a compensation signal is provided for minimizing the error. By thermoelectric cancellation, instead of sensing and processing the input voltage and load current separately and converting their products to power, the temperature increase is estimated based on that power. Thermoelectric cancellation generates an electrical cancellation signal in response to a thermal mechanism that generates an error source, thereby inherently matching more closely with the error source.

The error source is not caused by a uniform ambient temperature increase on the integrated circuit. If the voltage error is caused by a uniform increase in temperature across the integrated circuit, a dual temperature trim approach can be used to compensate for temperature drift to eliminate thermal errors. However, the error source is a temperature gradient, so the dual temperature trimming method will not adequately compensate for the second order effect caused by the temperature gradient of the entire integrated circuit.

Fig. 2 shows a block diagram for an example thermoelectric cancellation circuit. Bandgap core circuit 220 provides a bandgap reference voltage at its output. The bandgap voltage is set by the voltage across resistor 224, which is determined and adjusted by the current flowing through resistor 224. The output of the bandgap core circuit 220 is coupled to the input of a buffer amplifier 240. The output of buffer amplifier 240 is coupled to the feedback input of bandgap core circuit 220 and provided as a reference voltage to other circuits. The bandgap reference voltage is preferably very stable and accurate. However, without compensation, the bandgap reference voltage will provide an inaccurate reference voltage that varies with temperature.

A first compensation signal is provided at the output of the offset and slope correction trimming circuit 210. In many cases, the output of the offset and slope correction trimming circuit 210 is adjusted at ambient room temperature. A second compensation signal is provided at the output of the curvature correction trimming circuit 212 to reduce errors in the bandgap voltage caused by global temperature differences in ambient conditions. The adjustment of the output of the curvature correction trimming circuit 212 may be performed using a dual temperature test, where measurements are made at two known ambient temperatures and a temperature drift coefficient is determined.

The outputs of the slope correction trimming circuit 210 and the curvature correction trimming circuit 212 are currents that are added together at the summing block 214 and provided as correction currents to the resistor 224 to adjust the voltage across the resistor 224 to adjust the bandgap reference output voltage. However, there is another source of error that is caused by the temperature gradient from non-uniform self-heating within the circuit 200. The output of thermal error cancellation circuit 230 is coupled to resistor 224 and provides an additional error correction current to compensate for errors in the bandgap reference voltage caused by thermal gradients within circuit 200.

Thermal error cancellation circuit 230 may include an array of transistors that sense temperature and then convert the temperature difference into an error signal. Two temperature sensors may be used to sense a temperature gradient. In one embodiment, one of the temperature sensors is positioned close to the buffer amplifier and the other temperature sensor is positioned as far away from the buffer amplifier as possible. The farther apart two temperature sensors are on the integrated circuit at a given buffer amplifier power level, the higher the temperature gradient sensing signal. Although many temperature sensors may be used in thermal error cancellation circuit 230, it is preferable to use a temperature sensor that generates a high-precision, low-noise signal while maintaining a compact circuit.

FIG. 3 shows a schematic diagram for an example temperature sensor that provides a high-precision, low-noise signal representative of a temperature difference between two points in a circuit. The temperature sensor circuit 300 includes a transistor Q _a 、Q _b 、Q _c 、Q _d 、M ₀ And M ₁ . Transistor Q _a 、Q _b 、Q _c And Q _d Is a bipolar junction transistor, but in alternative embodiments the bipolar junction transistor may be replaced with a MOSFET. If a bipolar junction transistor is replaced with a MOSFET, references to base, emitter and collector in this specification should be replaced with gate, source and drain, respectively.

Q _a And Q _b Is connected together. Q (Q) _c And Q _d The bases of (2) are also connected together. Q (Q) _a And Q _c The bases of (2) are respectively connected to Q _a And Q _c Is provided. Transistor Q _a 、Q _b 、Q _c And Q _d Each of which has a resistor coupled between its emitter and ground. Resistor R _a And R is _c Are the same in resistance value and are respectively connected to Q _a And Q _c Is provided. In at least one embodiment, respectively connected to Q _b And Q _d The resistance values of the resistors of the emitters of (a) are the same.

M ₀ Is connected to M _l Gate, M of (2) ₀ Drain and Q of (2) _b Is provided. M is M ₁ Is connected to Q _d Is provided. M is M ₀ Is passed through resistor R ₀ Connected to a bandgap voltage source V _BG And M is ₁ Is passed through resistor R ₁ Connected to V _BG 。

If the supply voltage or load current increases, the power dissipation of the buffer amplifier will increase, thereby bringing about additional heating. An increase in buffer amplifier power proportional to the supply voltage and load current creates a temperature gradient in the bandgap reference circuit. The base-to-emitter voltage of a bipolar junction transistor depends on temperature in a Complementary To Absolute Temperature (CTAT) manner. Thus, as the supply voltage or load current increases, the base-to-emitter voltage of the individual devices increases proportionally. The dual temperature trimming circuit and the curvature trimming circuit can compensate and correct for global temperature increases if all devices are increased by the same amount. But the temperature difference causes a difference in base-to-emitter voltages of transistors at different locations due to non-uniform temperature increase throughout the circuit.

A signal can be provided to two transistors having two different regions, creating a base-to-emitter voltage difference (av _BE )。R _a The voltage across it is Q _a And Q _b Delta V between _BE . When to Q _a When the collector of (a) supplies a current, the output current is proportional to the supplied current. If provided to Q _a The output current is also the PTAT current, if the collector current of (c) is proportional to the absolute temperature (PTAT) current from the bandgap reference. Thus, if a temperature gradient exists, the current gain of the transistor is proportional to the gradient, and thus the transistor can be used as a temperature sensor. Q (Q) _a At a first location on the integrated circuit, and Q _b At the second location, any temperature difference between the two locations will therefore create Q _a And Q _b Delta V between _BE . With the development of temperature gradient, Q _a And Q _b Will not change by the same amount and therefore DeltaV _BE Creating a flow through R _a Is proportional to the temperature gradient.

With two temperature sensors S ₀ And S is ₁ The S is ₀ And S is ₁ Physically spaced on the integrated circuit at opposite ends of the temperature gradient generated by the power dissipation in the buffer amplifier. The corresponding bipolar transistor is located at S ₀ And S is ₁ The reverse is performed between them. Temperature sensor S ₀ Q of (2) _a And a temperature sensor S ₁ Q of (2) _d At a first location on an integrated circuitThis is close to, and at a temperature T ₀ . Temperature sensor S ₀ Q of (2) _b And a temperature sensor S ₁ Q of (2) _c Near each other at a second location on the integrated circuit and at a temperature T ₁ 。

Due to Q _a And Q _b Temperature difference between them, at temperature sensor S ₀ With first and second order components. Due to Q _c And Q _d Temperature difference between them, at temperature sensor S ₁ Will generate complementary currents having the same first and second order components but opposite polarity (polarity). Difference between two currents and T ₀ And T ₁ The temperature difference therebetween is proportional. When the currents are added together, the second order components are cancelled out, providing an output that is linearly proportional to the temperature gradient.

Line regulation errors can also be reduced by generating a signal proportional to the temperature gradient. Minimizing the line conditioning error requires proper scaling (scaled) of the line conditioning error to remove any temperature gradient error. Fig. 4 shows a schematic diagram for an example bandgap reference circuit 400, the example bandgap reference circuit 400 having temperature sensors at two locations in the circuit and having thermal error compensation.

The temperature sensor circuit includes a transistor Q _a 、Q _b 、Q _c 、Q _d 、Q _e 、M ₀ 、M ₁ 、M ₂ 、M ₃ 、M ₄ And M ₅ . Transistor Q _a 、Q _b 、Q _c 、Q _d And Q _e Is a bipolar junction transistor, but in alternative embodiments the bipolar junction transistor may be replaced with a MOSFET. If a bipolar junction transistor is replaced with a MOSFET, references to base, emitter and collector in this specification should be replaced with gate, source and drain, respectively.

Q _a And Q _b Is connected together and to M ₁ Is a source of (c). Q (Q) _c And Q _d Is connected together. Q (Q) _e And Q _f Is connected together and to M ₅ Is a source of (c). M is M ₁ And M ₂ Is connected together and to Q _a Is provided. M is M ₃ And M ₄ Is connected together and to Q _c Is provided. Transistor Q _a 、Q _b 、Q _c And Q _d With resistors R coupled between their emitters and ground, respectively _a 、R _b 、R _c And R is _d . Transistor Q _e And Q _f With resistor R coupled between its emitter and bandgap reference voltage output, respectively _e And R is _f 。

M ₅ Is connected to Q _e And Q _f Is formed on the base of the substrate. M is M ₅ Is connected to Q _e And M ₅ Is connected to ground. M is M ₁ And M ₃ Is connected to the bandgap reference voltage output 452.M is M ₂ Is connected to Q _e Is provided. M is M ₄ Is connected to Q _d Is provided. Q (Q) _a And Q _c Receives current I from bandgap reference circuit 420 _PTAT 。

Bandgap reference circuit 420 includes transistor Q ₀ 、Q ₁ 、Q ₂ 、Q ₃ 、Q ₄ 、Q ₅ 、Q ₆ 、Q ₇ And a buffer amplifier 450.Q (Q) ₀ 、Q ₁ 、Q ₅ 、Q ₆ And Q ₇ Is connected to the bandgap reference voltage output 452.Q (Q) ₇ Is connected to Q _a Is provided. Q (Q) ₆ Is connected to Q _c Is provided. Q (Q) ₅ 、Q ₆ And Q ₇ Is connected together. Q (Q) ₂ Is connected to Q ₃ And Q ₄ Base and Q of (2) ₂ Is provided. Q (Q) ₀ Is connected to Q ₁ Base and Q of (2) ₀ Is provided. Q (Q) ₃ Emitter pass resistor R ₄ Connected to Q ₄ And pass through resistor R _1b Connected to Q ₂ Is provided.

Buffer amplifier 450 has a first input connected to Q ₁ Emitter and Q of (2) ₂ Emitter and base of (a)And (5) a pole. Buffer amplifier 450 has a second input connected to Q ₃ Is connected to the emitter via a resistor R _1a Connected to Q ₀ Is provided. Buffer amplifier 450 has an output that is a bandgap reference voltage output 452.

With two temperature sensors S ₀ And S is ₁ Physically spaced at opposite ends of the integrated circuit to sense the temperature gradient generated by the power dissipation in the buffer amplifier 450. The corresponding bipolar transistor is located at S ₀ And S is ₁ The reverse is performed between them. From a temperature sensor S ₀ Q of (2) _a And from a temperature sensor S ₁ Q of (2) _d Near each other, preferably near buffer amplifier 450, at a first location on the integrated circuit, and at a temperature T ₀ . Temperature sensor S ₀ Q of (2) _b And a temperature sensor S ₁ Q of (2) _c Close to each other, preferably away from buffer amplifier 450, at a second location on the integrated circuit, and at a temperature T ₁ 。

Due to Q _a And Q _b Temperature difference between them, at temperature sensor S ₀ With first and second order components. Due to Q _c And Q _d Temperature difference between them, thus in the temperature sensor S ₁ Will generate a complementary current of opposite polarity, having a polarity equal to S ₀ The same first and second order components of the current in (a). Difference between two currents and T ₀ And T ₁ The temperature difference therebetween is proportional. When the currents are added together, the second order components are cancelled out, thus at M ₄ Produces an output at the collector that is linearly proportional to the temperature gradient.

M ₄ Is coupled to an offset current source 416. Offset current source 416 provides a trimming current that can be adjusted using a dual temperature test to reduce errors caused by uniform ambient temperature variations on integrated circuit 400. M is M ₄ Is coupled to the input of amplifier 440. Amplifier 440 is a digitally programmable current amplifier with its input coupled to M ₄ Is formed on the drain electrode of the transistor. M is M ₄ Is coupled to offset current source 416. The gain of the amplifier 440 may be adjusted to properly scale the output signal. In one embodiment, the amplifier 440 may be implemented as a series of current mirrors, each coupled to multiple taps on a resistor ladder. The output of amplifier 440 is a thermal error compensation current.

In an alternative embodiment, the amplifier 440 may comprise a digital-to-analog converter that receives the thermal error compensation signal as a digital command and generates a current signal in response. The output of amplifier 440 passes through resistor R ₂ Coupled to ground. The output of amplifier 440 is also coupled to Q ₃ And respectively through resistors R ₄ And R is _1b Coupled to Q ₂ And Q ₄ Is provided.

The thermal error cancellation signal has a PTAT current component that is a dual temperature trim offset current. In addition to thermal error cancellation trimming for a precision voltage reference, dual temperature trimming for offset and temperature coefficient slope correction may be performed. If the thermal error cancellation trim is performed prior to the dual temperature trim, then the additional PTAT output voltage component may be corrected during the dual temperature trim.

When trimming is performed on the output voltage of the device, the trimming code that provides the most accurate output voltage may be selected. However, no trimming is performed here to obtain a specific output voltage. Instead, trimming is performed to remove errors caused by the temperature gradient. Thus, the trimming method must take such differences into account.

Fig. 5 illustrates a flow chart of a method for determining Thermal Error Cancellation (TEC) codes. In step 510, the input voltage is set to V ₁ And measures the output voltage V _out (M1). In step 520, the input voltage is set to V ₂ And measures the output voltage V _out (M2). In step 530, M2 is subtracted from M1, and the difference between the two measurements (ΔV) is the error caused by the thermal gradient. In step 540, if DeltaV is within an acceptable tolerance of zero, TEC code adjustment is complete and the process proceeds to step 580 and ends. If DeltaV is not within an acceptable tolerance of zero, then the process continues to step 550.

In step 550, the direction of the next adjustment to the TEC code is determined in response to Δv. If the current DeltaV is reduced from the previous DeltaV, the TEC code is adjusted in the same direction as the previous adjustment, step 560. If the current DeltaV is increased from the previous DeltaV, then the TEC code is adjusted in the opposite direction as the previous adjustment, step 570. After step 560 or step 570, steps 510, 520 and 530 are repeated. The process continues until av is within acceptable tolerances of zero in step 540, at which point the process proceeds to step 580 and ends.

As used herein, "terminal," "node," "interconnect," "lead," and "pin" are used interchangeably. Unless specifically stated to the contrary, these terms generally refer to an interconnection between device elements, circuit elements, integrated circuits, devices, or other electronic or semiconductor components, or terminals thereof.

In this specification, "ground" includes chassis ground, floating ground, virtual ground, digital ground, common ground, and/or any other form of ground connection suitable or adapted for the teachings of this specification.

In this specification, even though operations are described in a particular order, some operations may be optional and the operations need not be performed in the particular order to achieve desirable results. In some examples, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the embodiments described above does not necessarily require such separation in all embodiments.

Modifications in the described embodiments are possible and other embodiments are possible within the scope of the claims.

Claims

1. An integrated circuit for temperature gradient compensation of a bandgap voltage, the integrated circuit comprising:

a bandgap core circuit having a bandgap feedback input, a bandgap adjustment input and a bandgap reference output;

a compensation resistor coupled between the bandgap adjustment input and a ground terminal;

an offset and slope correction circuit having an offset correction output coupled to the bandgap adjustment input;

a thermal error cancellation circuit, TEC, circuit having a TEC output coupled to the bandgap adjustment input, the TEC circuit comprising a first temperature sensor and a second temperature sensor spaced apart from each other, the TEC circuit configured to provide a signal at the TEC output in response to temperatures at the first temperature sensor and the second temperature sensor; and

an amplifier having an amplifier input and an amplifier output, the amplifier input coupled to the bandgap reference output.

2. The integrated circuit of claim 1, further comprising a curvature correction circuit having a curvature correction output coupled to the bandgap adjustment input.

3. The integrated circuit of claim 1, wherein:

the first temperature sensor includes:

a first transistor at a first location, the first transistor having first and second current terminals and a first control terminal, the first current terminal coupled to the first control terminal, the second current terminal coupled to the ground terminal through a first resistor, and the first current terminal providing a first temperature signal in response to a temperature at the first location;

a second transistor having third and fourth current terminals and a second control terminal, the second control terminal coupled to the first control terminal and the fourth current terminal coupled to the ground terminal through a second resistor, in a second position; and is also provided with

The second temperature sensor includes:

a third transistor at the second location, the third transistor having fifth and sixth current terminals and a third control terminal, the third control terminal coupled to the fifth current terminal, the sixth current terminal coupled to the ground terminal through a third resistor, and the fifth current terminal providing a second temperature signal in response to a temperature at the second location; and

a fourth transistor having seventh and eighth current terminals and a fourth control terminal at the first location, the fourth control terminal coupled to the third control terminal and the fourth current terminal coupled to the ground terminal through a fourth resistor.

4. The integrated circuit of claim 3, further comprising:

a fifth transistor having a ninth current terminal and a tenth current terminal, and a fifth control terminal, the ninth current terminal coupled to a reference voltage terminal, and the tenth current terminal coupled to the fifth control terminal and the third transistor current terminal; and

a sixth transistor having eleventh and twelfth current terminals and a sixth control terminal, the eleventh current terminal coupled to a reference voltage terminal and the twelfth current terminal coupled to the seventh current terminal.

5. The integrated circuit of claim 4, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are bipolar junction transistors, and the fifth transistor and the sixth transistor are FETs.

6. The integrated circuit of claim 1, wherein the bandgap core circuit is configured to provide a voltage at the bandgap reference output that is proportional to a voltage across the compensation resistor.

7. An integrated circuit for temperature gradient compensation of a bandgap voltage, the integrated circuit comprising:

a bandgap reference circuit having a bandgap adjustment input and a bandgap reference output;

a first transistor at a first location and having first and second current terminals and a first control terminal, and the second current terminal is coupled to a ground terminal through a first resistor;

a second transistor at a second location and having third and fourth current terminals and a second control terminal, the second control terminal coupled to the first control terminal and the fourth current terminal coupled to the ground terminal through a second resistor;

a third transistor at the second location and having fifth and sixth current terminals and a third control terminal, the sixth current terminal coupled to the ground terminal through a third resistor;

a fourth transistor at the first location and having seventh and eighth current terminals and a fourth control terminal, the fourth control terminal coupled to the third control terminal and the fourth current terminal coupled to the ground terminal through a fourth resistor;

a fifth transistor coupled between the bandgap reference output and the first control terminal and having a fifth control terminal coupled to the first current terminal;

a sixth transistor having a ninth current terminal and a tenth current terminal, and a sixth control terminal, the sixth control terminal coupled to the fifth control terminal, and the tenth current terminal coupled to the third transistor current terminal;

a seventh transistor coupled between the bandgap reference output and the third control terminal and having a seventh control terminal coupled to the fifth current terminal;

an eighth transistor having eleventh and twelfth current terminals and an eighth control terminal, the eighth control terminal coupled to the seventh control terminal and the twelfth current terminal coupled to the seventh current terminal; and

an amplifier having an amplifier input and an amplifier output, the amplifier input coupled to the eleventh current terminal, and the amplifier output configured to provide a signal proportional to a temperature difference between the first location and the second location.

8. The integrated circuit of claim 7, further comprising an offset correction current source coupled between the seventh current terminal and the ground terminal.

9. The integrated circuit of claim 7, wherein the amplifier is a programmable gain amplifier.

10. The integrated circuit of claim 9, wherein the programmable gain amplifier comprises current mirrors, and each current mirror is coupled to a tap on a resistor ladder.

11. The integrated circuit of claim 7, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are bipolar junction transistors, and the fifth transistor, the sixth transistor, the seventh transistor, and the eighth transistor are FETs.

12. The integrated circuit of claim 7, wherein a compensation resistor is coupled between the bandgap adjustment input and the ground terminal, and the voltage at the bandgap reference output is adjusted by varying the current flowing through the compensation resistor.

13. The integrated circuit of claim 7, wherein the bandgap reference circuit comprises a ninth transistor coupled between the bandgap reference output and the first transistor current terminal.

14. The integrated circuit of claim 13, wherein the bandgap reference circuit further comprises a tenth transistor coupled between the bandgap reference output and the fifth transistor current terminal.

15. A temperature sensor circuit, comprising:

a first transistor at a first location, the transistor having first and second current terminals and a first control terminal, the first current terminal coupled to the first control terminal, the second current terminal coupled to a ground terminal through a first resistor, and the first current terminal providing a first temperature signal in response to a temperature at the first location;

a second transistor having third and fourth current terminals and a second control terminal, the second control terminal coupled to the first control terminal and the fourth current terminal coupled to the ground terminal through a second resistor, in a second position;

16. The circuit of claim 15, further comprising:

a fifth transistor having a ninth current terminal and a tenth current terminal, and a fifth control terminal, the ninth current terminal coupled to a reference voltage terminal, and the tenth current terminal coupled to the fifth control terminal and the third current terminal; and

17. The circuit of claim 15, wherein the reference voltage terminal is coupled to a bandgap reference source.

18. The circuit of claim 16, wherein the first transistor, the second transistor, the third transistor, and the fourth transistor are bipolar junction transistors, and the fifth transistor and the sixth transistor are FETs.

19. The circuit of claim 15, wherein the signal at the seventh current terminal is proportional to a difference between the temperature at the first location and the temperature at the second location.

20. The circuit of claim 16, wherein the ninth current terminal is coupled to the reference voltage terminal through a fifth resistor and the eleventh current terminal is coupled to the reference voltage terminal through a sixth resistor.