A high and low temperature curvature compensation Zener reference voltage source circuit

Abstract

The present invention provides a high- and low-temperature curvature-compensated Zener reference voltage source circuit, applicable to the field of reference voltage source technology. By offsetting the positive temperature coefficient of the NP junction of Zener transistor Z and the negative temperature coefficient of the PN junction voltage between the base and emitter of transistor Q1, a low-temperature drift Zener reference with a certain curvature is formed. High- and low-temperature compensation is then performed to form a reference voltage and output a signal VOUT. This high- and low-temperature curvature-compensated Zener reference voltage source circuit can adjust the shape of the Zener reference voltage waveform through high- and low-temperature curvature compensation, thereby reducing fluctuations in the Zener reference voltage when the ambient temperature and operating temperature change.

Description

Technical Field

[0001] The present invention belongs to the technical field of reference voltage sources, and in particular relates to a high and low temperature curvature compensation Zener reference voltage source circuit. Background Art

[0002] Digitally controlled reference voltage sources are extremely important components of modern analog integrated circuits. They provide reference voltages for series voltage regulator circuits, A / D and D / A converters, and are also the regulated power supply or excitation source for most sensors.

[0003] Integrated circuit systems often require precision voltage reference circuits. The accuracy of the reference determines the accuracy of the system's output voltage. However, power supply systems are often composed of power devices, which inevitably generate heat during operation. Sometimes, power supply systems must also operate effectively in low-temperature outdoor environments in winter, requiring a precision voltage reference with a good temperature coefficient.

[0004] The temperature curve of the traditional first-order zero temperature coefficient reference is mostly parabolic in the full temperature range, which sometimes cannot meet the actual requirements. This requires the design of a high and low temperature curvature compensation Zener reference circuit for curvature correction. Summary of the Invention

[0005] In view of the above problems in the prior art, the purpose of the present invention is to provide a high-low temperature curvature compensated Zener reference voltage source circuit, which can adjust the shape of the Zener reference voltage waveform through high-low temperature curvature compensation, and reduce the fluctuation of the Zener reference voltage when the ambient temperature and operating temperature change.

[0006] A high and low temperature curvature compensation Zener reference voltage source circuit forms a low temperature drift Zener reference with a certain curvature by canceling out the positive temperature coefficient of the NP junction of the Zener transistor Z and the negative temperature coefficient of the PN junction voltage between the base and emitter of the transistor Q1. The circuit also forms a reference voltage and outputs a signal VOUT through high and low temperature compensation.

[0007] The circuit includes a voltage source VCC, a Zener diode Z and a current source I1, wherein the voltage source VCC, the current source I1 and the Zener diode Z are connected in series to form a closed loop, and the negative electrode of the voltage source VCC is grounded;

[0008] The two ends of the Zener tube Z are connected in parallel with resistor 1 R1, resistor 2 R2, resistor 3 R3, resistor 4 R4 and resistor 5 R5 which are connected in series in sequence;

[0009] The circuit further includes a transistor Q1, wherein the base of the transistor Q1 is connected to the circuit between the fourth resistor R4 and the fifth resistor R5, the collector is connected to the circuit between the second resistor R2 and the third resistor R3, and the emitter is grounded;

[0010] The circuit also includes a transistor 2 Q2 and a transistor 3 Q3 whose collectors are connected to each other. The base of the transistor 2 Q2 is connected to the circuit between the resistor 3 R3 and the resistor 4 R4, and the emitter is connected to the resistor 6 R6. The base of the transistor 3 Q3 is connected to the reference voltage source VREF, and the emitter is connected to the resistor 7 R7. The other ends of the resistors 6 R6 and R7 are both electrically connected to the resistor 8 R8, and the other ends of the resistor 8 R8 and the reference voltage source VREF are both grounded.

[0011] In order to meet the input voltage requirement of the circuit, the voltage of the voltage source VCC is greater than 7V.

[0012] The voltage of the reference voltage source VREF is 1.25V.

[0013] The beneficial effects of the present invention are as follows: the high and low temperature curvature compensation Zener reference voltage source circuit utilizes the base current I B2 At low temperatures, the currents of resistors R2 and R3 are increased to improve the voltage of the low-temperature section, thereby realizing curvature correction of the negative temperature coefficient of Zener diode Z, and adjusting the ratio between resistors R6 and R8 to adjust the low-temperature curvature compensation; the current of resistor R2 is increased by utilizing the collector shunt characteristics of transistor Q1, thereby raising the reference high-temperature section to realize curvature correction of the positive temperature coefficient of Zener diode Z, and adjusting the ratio between resistors R2 and R3 to adjust the high-temperature curvature compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 is a circuit diagram of the present invention;

[0016] Figure 2 It is a schematic diagram of the temperature characteristics of a Zener reference voltage source in the prior art;

[0017] Figure 3 is a schematic diagram of the temperature characteristics of the Zener reference voltage source of the present invention;

[0018] Figure 4 is the base current I of transistor Q2 of the present invention B2 Schematic diagram of the relationship with temperature;

[0019] Figure 5 is the base current I of the transistor Q1 of the present invention B1 Schematic diagram of the relationship with temperature;

[0020] Figure 6 is the collector current I of the transistor Q1 of the present inventionC1 Schematic diagram of the relationship with temperature. DETAILED DESCRIPTION

[0021] like Figure 2 As shown, the output curve of the reference voltage without high and low temperature curvature compensation in the prior art is parabolic in the full temperature range, with a positive temperature coefficient in the low temperature section and a negative temperature coefficient in the high temperature section, and has large fluctuations.

[0022] Example 1

[0023] like Figure 1 、 Figures 3 to 6 As shown, a high and low temperature curvature compensation Zener reference voltage source circuit is formed. The positive temperature coefficient of the NP junction of the Zener transistor Z and the negative temperature coefficient of the PN junction voltage between the base and emitter of the transistor Q1 cancel each other out to form a low temperature drift Zener reference with a certain curvature. Through high and low temperature compensation, a reference voltage is formed and the output signal VOUT is output.

[0024] The working principle of the high and low temperature curvature compensation Zener reference voltage source circuit is analyzed as follows:

[0025] After the voltage source VCC supplies power, the current source I1 and the current source I2 that form the current mirror enable the entire circuit to start working normally. After ignoring the curvature compensation, the Zener reference voltage V ZREF The calculation formula is:

[0026]

[0027] Among them, V ZENER is the turn-on voltage threshold of the Zener diode Z, which is a positive temperature coefficient, V BE1 is the voltage difference between the base and emitter of transistor Q1, which is a negative temperature coefficient. By adjusting the ratio of the resistors in formula (1), the positive temperature coefficient and the negative temperature coefficient can be offset to obtain the ultra-low temperature drift reference voltage V ZREF , that is, Figure 1 The output signal VOUT is shown.

[0028] like Figure 4 As shown, when V B2 >V REF When

[0029]

[0030] When the transistor Q2 is turned on, the base current of the transistor Q2 is I B2 A current is generated, where V B2 is the base voltage of transistor Q2, V BE1 ≈V BE2 ≈V BE3 =V BE , VBE is the voltage difference between the base and emitter of the NPN transistor Q.

[0031] Because at low temperature, V BE Getting bigger will cause I B2 becomes larger, and V REF Unchanged, and because I B2 = C2 / 2, β2 is the amplification factor of transistor 2 Q2, and

[0032]

[0033] Therefore, using V BE The negative temperature coefficient is adjusted by adjusting the resistance parameters and the current source I2 parameters in formula (2) so that the resistor R7, the resistor R6, the current source I2, and the resistor R8 determine the base current I of the transistor Q2 at low temperature. B2 The starting temperature point can make the base current I B2 The start-up shunt will achieve the best low temperature compensation. At this time, the base current of transistor 2 Q2 I B2 At low temperatures, the currents of resistors R3 and R2 are increased, which raises the voltage in the low temperature section and performs effective low temperature compensation. At the same time, the base current I B1 It will also effectively compensate as the temperature decreases.

[0034] like Figure 5 As shown, the base current of transistor Q1 is defined as I B1 , the magnification is β1,

[0035] but

[0036]

[0037] The amplification factor β1 of the transistor Q1 increases with increasing temperature. Adjusting the resistance ratio in formula (3) can achieve the corresponding high-temperature curvature compensation effect.

[0038] like Figure 6 As shown, the collector shunt characteristic of transistor Q1 is used to increase the current of resistor R2, thereby raising the reference high temperature section and realizing the curvature correction of the positive temperature coefficient of Zener diode Z. The collector current of transistor Q1 is I C1 , specifically, I C1 The calculation formula is:

[0039]

[0040] In this high- and low-temperature curvature-compensated Zener reference voltage source circuit, the reference voltage changes by only about 0.155mV within the temperature range of -40 to 150°C, achieving the ultra-low temperature drift standard of 0.189ppm / °C. The resistors are all low-temperature-coefficient thin-film resistors, and the effect is better when the Zener diodes are buried-layer Zener diodes.

[0041] like Figure 1 As shown, specifically, the circuit includes a voltage source VCC, a Zener diode Z and a current source I1. The voltage source VCC, the current source I1 and the Zener diode Z are connected in series to form a closed loop. The negative pole of the voltage source VCC is grounded. The voltage of the voltage source VCC needs to be greater than 7V.

[0042] The two ends of the Zener tube Z are connected in parallel with resistor 1 R1, resistor 2 R2, resistor 3 R3, resistor 4 R4 and resistor 5 R5 which are connected in series in sequence;

[0043] The circuit further includes a transistor Q1, wherein the base of the transistor Q1 is connected to the circuit between the fourth resistor R4 and the fifth resistor R5, the collector is connected to the circuit between the second resistor R2 and the third resistor R3, and the emitter is grounded;

[0044] The circuit also includes a transistor Q2 and a transistor Q3 whose collectors are connected to each other. The base of the transistor Q2 is connected to the circuit between the resistor R3 and the resistor R4, and the emitter is connected to the resistor R6. The base of the transistor Q3 is connected to the reference voltage source VREF, and the emitter is connected to the resistor R7. The other ends of the resistors R6 and R7 are both electrically connected to the resistor R8. The other ends of the resistor R8 and the reference voltage source VREF are both grounded. The voltage of the reference voltage source VREF is 1.25V, which can be powered by a traditional 1.25V bandgap reference designed internally, or by an external 1.25V voltage source.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A high and low temperature curvature compensation Zener reference voltage source circuit, characterized in that: The positive temperature coefficient of the NP junction of the Zener tube Z and the negative temperature coefficient of the PN junction voltage between the base and emitter of the transistor Q1 cancel each other out, forming a low-temperature drift Zener reference with a certain curvature. Through high and low temperature compensation, a reference voltage is formed and the output signal VOUT is generated. The high and low temperature curvature compensation Zener reference voltage source circuit includes a voltage source VCC, a Zener diode Z, and a current source I1. The voltage source VCC, the current source I1, and the Zener diode Z are connected in series to form a closed loop. The negative electrode of the voltage source VCC is grounded, wherein the cathode of the Zener diode Z is connected to the negative electrode of the current source I1, and the anode of the Zener diode Z is connected to the negative electrode of the voltage source VCC. The two ends of the Zener tube Z are connected in parallel with resistors R1, R2, R3, R4 and R5, which are connected in series in sequence. One end of the resistor R1 is connected to the cathode of the Zener tube Z, and one end of the resistor R5 is connected to the anode of the Zener tube Z. The high and low temperature curvature compensation Zener reference voltage source circuit further includes a transistor Q1, wherein the base of the transistor Q1 is connected to the circuit between the fourth resistor R4 and the fifth resistor R5, the collector is connected to the circuit between the second resistor R2 and the third resistor R3, and the emitter is grounded; The high and low temperature curvature compensation Zener reference voltage source circuit also includes a transistor 2 Q2 and a transistor 3 Q3 whose collectors are connected to each other. The base of the transistor 2 Q2 is connected to the circuit between the resistor 3 R3 and the resistor 4 R4, and the emitter is connected to the resistor 6 R6. The base of the transistor 3 Q3 is connected to the reference voltage source VREF, and the emitter is connected to the resistor 7 R7. The other ends of the resistors 6 R6 and 7 R7 are both electrically connected to the resistor 8 R8, and the other ends of the resistor 8 R8 and the reference voltage source VREF are both grounded.

2. The high and low temperature curvature compensation Zener reference voltage source circuit according to claim 1, characterized in that: The voltage of the voltage source VCC is greater than 7V.

3. The high and low temperature curvature compensation Zener reference voltage source circuit according to claim 1, characterized in that: The voltage of the reference voltage source VREF is 1.25V.

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