A high-precision low-temperature drift voltage reference source

Abstract

The present invention provides a high-precision low-temperature drift voltage reference source in the field of voltage reference source technology, including a low-noise linear voltage stabilization module, a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module, a voltage attenuation module and an analog-to-digital conversion chip U6; the low-noise linear voltage stabilization module is respectively connected to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6; the input end of the voltage addition module is respectively connected to the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and the output end is connected to the input end of the voltage attenuation module; the output end of the voltage attenuation module is connected to the analog-to-digital conversion chip U6. The advantages of the present invention are: the temperature stability of the voltage reference source is greatly improved, thereby greatly improving the voltage output accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage reference sources, and in particular to a high-precision low-temperature drift voltage reference source. Background Art

[0002] Voltage reference source, also known as reference voltage source, is an extremely important component of contemporary analog integrated circuits. It provides reference voltage for series voltage regulator circuits, A / D and D / A converters, and is also the voltage regulator power supply or excitation source for most sensors. As various instruments and meters have higher and higher requirements for measurement accuracy, the requirements for sampling stability within a certain temperature range have become higher and higher, which has led to the need to further improve the temperature stability of voltage reference sources.

[0003] Therefore, how to provide a high-precision, low-temperature drift voltage reference source to improve the temperature stability of the voltage reference source and thereby improve the voltage output accuracy has become an urgent problem to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a high-precision low-temperature drift voltage reference source to improve the temperature stability of the voltage reference source and thereby improve the voltage output accuracy.

[0005] The present invention is implemented as follows: a high-precision low-temperature drift voltage reference source, including a low-noise linear voltage stabilization module, a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module, a voltage attenuation module and an analog-to-digital conversion chip U6;

[0006] The low-noise linear voltage stabilization module is respectively connected to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6; the input end of the voltage addition module is respectively connected to the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and the output end is connected to the input end of the voltage attenuation module; the output end of the voltage attenuation module is connected to the analog-to-digital conversion chip U6.

[0007] Furthermore, the low-noise linear voltage regulator module includes a low voltage difference linear voltage regulator chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4;

[0008] Pin 1 of the low voltage difference linear voltage regulator chip U1 is connected to capacitor C1, capacitor C2, capacitor C3 and capacitor C4 and grounded, pins 2 and 4 are connected to capacitor C3, capacitor C4, a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module and a voltage attenuation module, and pin 3 is connected to capacitor C1 and capacitor C2.

[0009] Furthermore, the low-noise linear voltage regulator module further includes a low voltage difference linear voltage regulator chip U2, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8;

[0010] Pin 1 of the low voltage difference linear voltage regulator chip U2 is connected to capacitors C5, C6, C7 and C8 and grounded, pins 2 and 4 are connected to capacitors C7, C8 and analog-to-digital conversion chip U6, and pin 3 is connected to capacitors C5 and C6.

[0011] Further, the positive temperature coefficient reference source module includes a positive temperature coefficient reference source chip U3, a capacitor C9, a capacitor C10, a capacitor C11 and a capacitor C12;

[0012] Pin 2 of the positive temperature coefficient reference source chip U3 is connected to capacitor C9, capacitor C10 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C9 and capacitor C10 and grounded, pin 6 is connected to capacitor C11, capacitor C12 and a voltage addition module; the capacitor C11 is connected to capacitor C12 and grounded.

[0013] Further, the negative temperature coefficient reference source module includes a negative temperature coefficient reference source chip U4, a capacitor C13, a capacitor C14, a capacitor C15 and a capacitor C16;

[0014] Pin 2 of the negative temperature coefficient reference source chip U4 is connected to capacitor C15, capacitor C16 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C15 and capacitor C16 and grounded, pin 6 is connected to capacitor C13, capacitor C14 and a voltage addition module; capacitor C13 is connected to capacitor C14 and grounded.

[0015] Furthermore, the output voltages of the positive temperature coefficient reference source chip U3 and the negative temperature coefficient reference source chip U4 are the same, and the temperature offset curves are opposite.

[0016] Further, the voltage adding module includes an operational amplifier U5A, a capacitor C17, a capacitor C18, a resistor R1, a resistor R2, a resistor R4, a resistor R7 and a resistor R10;

[0017] Pin 1 of the operational amplifier U5A is connected to resistor R2, resistor R10 and a voltage attenuation module, pin 2 is connected to resistor R7 and resistor R10, pin 3 is connected to resistor R1 and resistor R4, and pin 8 is connected to capacitor C17, capacitor C18 and a low-noise linear voltage regulator module; the resistor R1 is connected to a positive temperature coefficient reference source module; the resistor R4 is connected to a negative temperature coefficient reference source module; the resistor R2, resistor R7, capacitor C17 and capacitor C18 are all grounded.

[0018] Further, the voltage attenuation module includes an operational amplifier U5B, a resistor R3, a resistor R5, a resistor R6, a resistor R8 and a resistor R9;

[0019] Pin 5 of the operational amplifier U5B is connected to resistors R3 and R6, pin 6 is connected to resistors R8 and R9, pin 7 is connected to resistors R5, R9 and analog-to-digital conversion chip U6, and pin 8 is connected to a low-noise linear voltage regulator module; the resistor R6 is connected to a voltage addition module; the resistors R3, R5 and R8 are all grounded.

[0020] Furthermore, the pin REF I+ of the analog-to-digital conversion chip U6 is connected to the voltage attenuation module, and the pins AVDD1A, IOVDD, AVDD1 B, AVDD2B, AVDD2A, and AVDD4 are connected to the low-noise linear voltage regulator module.

[0021] The advantages of the present invention are:

[0022] By setting a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module and a voltage attenuation module, the positive temperature coefficient reference source module and the negative temperature coefficient reference source module respectively include a positive temperature coefficient reference source chip U3 and a negative temperature coefficient reference source chip U4 with the same output voltage and opposite temperature offset curves. The output voltages of the positive temperature coefficient reference source module and the negative temperature coefficient reference source module are superimposed through the voltage addition module to allow the offset voltages to cancel each other out, and then the superimposed voltage is halved through the voltage attenuation module, so that the reference source of the input analog-to-digital conversion chip U6 remains stable, overcoming the influence of temperature on voltage, and ultimately greatly improving the temperature stability of the voltage reference source, thereby greatly improving the voltage output accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0024] Figure 1 The invention discloses a circuit principle block diagram of a high-precision low-temperature drift voltage reference source.

[0025] Figure 2 It is a circuit diagram of the low-noise linear voltage stabilization module of the present invention.

[0026] Figure 3 The invention discloses a circuit diagram of a positive temperature coefficient reference source module.

[0027] Figure 4 The invention discloses a circuit diagram of a negative temperature coefficient reference source module.

[0028] Figure 5 It is a circuit diagram of the voltage addition module of the present invention.

[0029] Figure 6 It is a circuit diagram of the voltage attenuation module of the present invention.

[0030] Figure 7 It is a circuit diagram of the analog-to-digital conversion chip U6 of the present invention.

[0031] Figure 8 It is a schematic diagram of the temperature offset curve of the positive temperature coefficient reference source chip U3 of the present invention.

[0032] Fig. 9 It is a schematic diagram of the temperature offset curve of the negative temperature coefficient reference source chip U4 of the present invention. DETAILED DESCRIPTION

[0033] The technical solution in the embodiments of the present application has the following overall idea: two reference source modules (a positive temperature coefficient reference source module and a negative temperature coefficient reference source module) with the same output voltage and opposite temperature offset curves are superimposed through a voltage addition module, and then the superimposed voltage is halved using a voltage attenuation module to offset the offset voltage, thereby improving the temperature stability of the voltage reference source and thereby improving the voltage output accuracy.

[0034] Please refer to Figures 1 to 9 As shown, a preferred embodiment of a high-precision low-temperature drift voltage reference source of the present invention includes a low-noise linear voltage regulator module (LDO module), a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module, a voltage attenuation module and an analog-to-digital conversion chip U6 (ADC module); the low-noise linear voltage regulator module is used to supply power to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6, and reduce the noise impact in the circuit; the output voltage of the positive temperature coefficient reference source module increases with the increase of temperature, and the output voltage of the negative temperature coefficient reference source module decreases with the increase of temperature; the voltage addition module is used to superimpose the output voltages of the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and output them to the voltage attenuation module; the voltage attenuation module is used to halve the input voltage and output it to the analog-to-digital conversion chip U6 as a reference source; the analog-to-digital conversion chip U6 is used to convert an analog voltage signal into a discrete digital signal;

[0035] The low-noise linear voltage stabilization module is respectively connected to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6; the input end of the voltage addition module is respectively connected to the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and the output end is connected to the input end of the voltage attenuation module; the output end of the voltage attenuation module is connected to the analog-to-digital conversion chip U6.

[0036] The low-noise linear voltage regulator module includes a low voltage difference linear voltage regulator chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; the model of the low voltage difference linear voltage regulator chip U1 is preferably AMS1117-5, which is used to output 5V VOUT-1 to power the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module and the voltage attenuation module; the capacitor C1 and the capacitor C2 are used as input filter capacitors of the low voltage difference linear voltage regulator chip U1; the capacitor C3 and the capacitor C4 are used as output capacitors of the low voltage difference linear voltage regulator chip U1;

[0037] Pin 1 of the low voltage difference linear voltage regulator chip U1 is connected to capacitor C1, capacitor C2, capacitor C3 and capacitor C4 and grounded, pins 2 and 4 are connected to capacitor C3, capacitor C4, a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module and a voltage attenuation module, and pin 3 is connected to capacitor C1 and capacitor C2.

[0038] The low-noise linear voltage regulator module also includes a low voltage difference linear voltage regulator chip U2, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8; the model of the low voltage difference linear voltage regulator chip U2 is preferably AMS1117-3.3, which is used to output 3.3V VOUT-2 to power the analog-to-digital conversion chip U6; the capacitor C5 and the capacitor C6 are used as input filter capacitors of the low voltage difference linear voltage regulator chip U2; the capacitor C7 and the capacitor C8 are used as output capacitors of the low voltage difference linear voltage regulator chip U2;

[0039] Pin 1 of the low voltage difference linear voltage regulator chip U2 is connected to capacitors C5, C6, C7 and C8 and grounded, pins 2 and 4 are connected to capacitors C7, C8 and analog-to-digital conversion chip U6, and pin 3 is connected to capacitors C5 and C6.

[0040] The positive temperature coefficient reference source module includes a positive temperature coefficient reference source chip U3, a capacitor C9, a capacitor C10, a capacitor C11 and a capacitor C12; the model of the positive temperature coefficient reference source chip U3 is preferably ADR431, and the output voltage gradually increases with the increase of temperature within 0-70°C; the capacitors C9 and C10 serve as input filter capacitors of the positive temperature coefficient reference source chip U3; the capacitors C11 and C12 serve as output capacitors of the positive temperature coefficient reference source chip U3;

[0041] Pin 2 of the positive temperature coefficient reference source chip U3 is connected to capacitor C9, capacitor C10 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C9 and capacitor C10 and grounded, pin 6 is connected to capacitor C11, capacitor C12 and a voltage addition module; the capacitor C11 is connected to capacitor C12 and grounded.

[0042] The negative temperature coefficient reference source module includes a negative temperature coefficient reference source chip U4, a capacitor C13, a capacitor C14, a capacitor C15 and a capacitor C16; the model of the negative temperature coefficient reference source chip U4 is preferably ADR4525, and the output voltage gradually decreases with the increase of temperature within 0-70°C; the capacitors C15 and C16 serve as input filter capacitors of the negative temperature coefficient reference source chip U4; the capacitors C13 and C14 serve as output capacitors of the negative temperature coefficient reference source chip U4;

[0043] Pin 2 of the negative temperature coefficient reference source chip U4 is connected to capacitor C15, capacitor C16 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C15 and capacitor C16 and grounded, pin 6 is connected to capacitor C13, capacitor C14 and a voltage addition module; capacitor C13 is connected to capacitor C14 and grounded.

[0044] The output voltages of the positive temperature coefficient reference source chip U3 and the negative temperature coefficient reference source chip U4 are the same, and their temperature offset curves are opposite.

[0045] The voltage addition module includes an operational amplifier U5A, a capacitor C17, a capacitor C18, a resistor R1, a resistor R2, a resistor R4, a resistor R7 and a resistor R10; the model of the operational amplifier U5A is preferably ADR4525, which has the advantage of extremely low temperature offset; the resistor R2 is used as a load output by the operational amplifier U5A; the resistors R1, R4, R7 and R10 are used as gain matching resistors of the operational amplifier U5A; by configuring the resistance values ​​of the resistor R1 and the resistor R4 to be the same, and the resistance values ​​of the resistor R7 and the resistor R10 to be the same, the output (VREF-ADD) of the voltage addition module is the output voltage (VREF-1) of the superimposed positive temperature coefficient reference source module and the output voltage (VREF-2) of the negative temperature coefficient reference source module;

[0046] Pin 1 of the operational amplifier U5A is connected to resistor R2, resistor R10 and a voltage attenuation module, pin 2 is connected to resistor R7 and resistor R10, pin 3 is connected to resistor R1 and resistor R4, and pin 8 is connected to capacitor C17, capacitor C18 and a low-noise linear voltage regulator module; the resistor R1 is connected to a positive temperature coefficient reference source module; the resistor R4 is connected to a negative temperature coefficient reference source module; the resistor R2, resistor R7, capacitor C17 and capacitor C18 are all grounded.

[0047] The voltage attenuation module includes an operational amplifier U5B, a resistor R3, a resistor R5, a resistor R6, a resistor R8 and a resistor R9; the resistor R5 is used as a load output by the operational amplifier U5B; the resistors R3, R6, R8 and R9 are used as attenuation matching resistors of the operational amplifier U5B; by configuring R6=R8=2*R3=2*R9, the output voltage (VREF) of the voltage attenuation module is half of the input voltage (VREF-ADD); since the temperature offset curves of the positive temperature coefficient reference source chip U3 and the negative temperature coefficient reference source chip U4 within 0-70°C are opposite, the influence of temperature on the output voltage can be offset, thereby making the temperature stability of the output voltage of the voltage attenuation module much higher than that of the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, that is, the voltage reference source has the characteristics of high-precision low-temperature drift;

[0048] Pin 5 of the operational amplifier U5B is connected to resistors R3 and R6, pin 6 is connected to resistors R8 and R9, pin 7 is connected to resistors R5, R9 and analog-to-digital conversion chip U6, and pin 8 is connected to a low-noise linear voltage regulator module; the resistor R6 is connected to a voltage addition module; the resistors R3, R5 and R8 are all grounded.

[0049] The pin REFI+ of the analog-to-digital conversion chip U6 is connected to the voltage attenuation module, and the pins AVDD1A, IOVDD, AVDD1B, AVDD2B, AVDD2A, and AVDD4 are connected to the low-noise linear voltage regulator module. The model of the analog-to-digital conversion chip U6 is preferably AD7771, which has the advantage of high precision; the output voltage (VREF) of the voltage attenuation module is used as the external reference source of the analog-to-digital conversion chip U6.

[0050] Working principle of the present invention:

[0051] The low-noise linear voltage regulator module supplies power to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6 respectively; the voltage addition module superimposes the output voltages of the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and then inputs the voltage to the voltage attenuation module; the voltage attenuation module halves the input voltage and outputs it to the analog-to-digital conversion chip U6 as an external reference source for the analog-to-digital conversion chip U6.

[0052] In summary, the advantages of the present invention are:

[0053] By setting a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module and a voltage attenuation module, the positive temperature coefficient reference source module and the negative temperature coefficient reference source module respectively include a positive temperature coefficient reference source chip U3 and a negative temperature coefficient reference source chip U4 with the same output voltage and opposite temperature offset curves. The output voltages of the positive temperature coefficient reference source module and the negative temperature coefficient reference source module are superimposed through the voltage addition module to allow the offset voltages to cancel each other out, and then the superimposed voltage is halved through the voltage attenuation module, so that the reference source of the input analog-to-digital conversion chip U6 remains stable, overcoming the influence of temperature on voltage, and ultimately greatly improving the temperature stability of the voltage reference source, thereby greatly improving the voltage output accuracy.

[0054] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A high-precision low-temperature drift voltage reference source, characterized in that: It includes a low-noise linear voltage regulator module, a positive temperature coefficient reference source module, a negative temperature coefficient reference source module, a voltage addition module, a voltage attenuation module and an analog-to-digital conversion chip U6; The low-noise linear voltage stabilization module is respectively connected to the positive temperature coefficient reference source module, the negative temperature coefficient reference source module, the voltage addition module, the voltage attenuation module and the analog-to-digital conversion chip U6; the input end of the voltage addition module is respectively connected to the positive temperature coefficient reference source module and the negative temperature coefficient reference source module, and the output end is connected to the input end of the voltage attenuation module; the output end of the voltage attenuation module is connected to the analog-to-digital conversion chip U6; The low noise linear voltage regulator module includes a low voltage difference linear voltage regulator chip U1, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; Pin 1 of the low voltage difference linear voltage regulator chip U1 is connected to capacitor C1, capacitor C2, capacitor C3 and capacitor C4 and grounded, pins 2 and 4 are connected to capacitor C3, capacitor C4, positive temperature coefficient reference source module, negative temperature coefficient reference source module, voltage addition module and voltage attenuation module, and pin 3 is connected to capacitor C1 and capacitor C2; The positive temperature coefficient reference source module includes a positive temperature coefficient reference source chip U3, a capacitor C9, a capacitor C10, a capacitor C11 and a capacitor C12; Pin 2 of the positive temperature coefficient reference source chip U3 is connected to capacitor C9, capacitor C10 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C9 and capacitor C10 and grounded, pin 6 is connected to capacitor C11, capacitor C12 and a voltage addition module; the capacitor C11 is connected to capacitor C12 and grounded.

2. A high-precision low-temperature drift voltage reference source as claimed in claim 1, characterized in that: The low noise linear voltage regulator module also includes a low voltage difference linear voltage regulator chip U2, a capacitor C5, a capacitor C6, a capacitor C7 and a capacitor C8; Pin 1 of the low voltage difference linear voltage regulator chip U2 is connected to capacitors C5, C6, C7 and C8 and grounded, pins 2 and 4 are connected to capacitors C7, C8 and analog-to-digital conversion chip U6, and pin 3 is connected to capacitors C5 and C6.

3. A high-precision low-temperature drift voltage reference source as claimed in claim 1, characterized in that: The negative temperature coefficient reference source module includes a negative temperature coefficient reference source chip U4, a capacitor C13, a capacitor C14, a capacitor C15 and a capacitor C16; Pin 2 of the negative temperature coefficient reference source chip U4 is connected to capacitor C15, capacitor C16 and a low-noise linear voltage regulator module, pin 4 is connected to capacitor C15 and capacitor C16 and grounded, pin 6 is connected to capacitor C13, capacitor C14 and a voltage addition module; capacitor C13 is connected to capacitor C14 and grounded.

4. A high-precision low-temperature drift voltage reference source as claimed in claim 3, characterized in that: The output voltages of the positive temperature coefficient reference source chip U3 and the negative temperature coefficient reference source chip U4 are the same, and their temperature offset curves are opposite.

5. A high-precision low-temperature drift voltage reference source as claimed in claim 1, characterized in that: The voltage adding module includes an operational amplifier U5A, a capacitor C17, a capacitor C18, a resistor R1, a resistor R2, a resistor R4, a resistor R7 and a resistor R10; Pin 1 of the operational amplifier U5A is connected to resistor R2, resistor R10 and a voltage attenuation module, pin 2 is connected to resistor R7 and resistor R10, pin 3 is connected to resistor R1 and resistor R4, and pin 8 is connected to capacitor C17, capacitor C18 and a low-noise linear voltage regulator module; the resistor R1 is connected to a positive temperature coefficient reference source module; the resistor R4 is connected to a negative temperature coefficient reference source module; the resistor R2, resistor R7, capacitor C17 and capacitor C18 are all grounded.

6. A high-precision low-temperature drift voltage reference source as claimed in claim 1, characterized in that: The voltage attenuation module includes an operational amplifier U5B, a resistor R3, a resistor R5, a resistor R6, a resistor R8 and a resistor R9; Pin 5 of the operational amplifier U5B is connected to resistors R3 and R6, pin 6 is connected to resistors R8 and R9, pin 7 is connected to resistors R5, R9 and analog-to-digital conversion chip U6, and pin 8 is connected to a low-noise linear voltage regulator module; the resistor R6 is connected to a voltage addition module; the resistors R3, R5 and R8 are all grounded.

7. A high-precision low-temperature drift voltage reference source as claimed in claim 1, characterized in that: The pin REFI+ of the analog-to-digital conversion chip U6 is connected to the voltage attenuation module, and the pins AVDD1A, IOVDD, AVDD1 B, AVDD2B, AVDD2A, and AVDD4 are connected to the low-noise linear voltage regulator module.

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