Reference voltage source circuit, high-order compensation method of reference voltage source circuit and chip

Abstract

The invention relates to a reference voltage source circuit for high-order compensation based on a BJT forward current gain temperature characteristic, a high-order compensation method of the reference voltage source circuit and a chip, the reference voltage source circuit for high-order compensation based on the BJT forward current gain temperature characteristic comprises a CTAT circuit and a PTAT circuit, the CTAT circuit comprises a first BJT, and the PTAT circuit comprises a second BJT. The emitter electrode of the first BJTQ1 is connected with a PTAT circuit, the collector electrode and the base electrode of the first BJTQ1 are connected and are connected with a common ground, the PTAT circuit comprises a second BJTQ2, the current density ratio of the first BJTQ1 to the second BJTQ2 is 1: N, the collector electrode and the base electrode of the second BJTQ2 are connected and are connected with the common ground, and the reference voltage source circuit is configured in a way that the first BJTQ1 and the second BJTQ2 are connected with the common ground. By configuring the bias current of the second BJTQ2, high-order compensation of the reference voltage source circuit is achieved, high-order compensation is achieved through a simple first-order circuit, power consumption and cost are saved, and the requirement of a high-precision application scene can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of chip design, and in particular to a reference voltage source circuit, a high-order compensation method for the reference voltage source circuit, and a chip. Background Art

[0002] A reference voltage source or bandgap reference source is used to provide a reference voltage to the circuit that does not change with temperature and power supply voltage. Figure 1 As shown, by using the complementary to absolute temperature (CTAT) V BE voltage, and the voltage ΔV proportional to absolute temperature (PTAT) BE The mathematical expression of the output voltage is V OUT =V BE +2R1 / R2*kT / q*lnJ1 / J2, this solution introduces ΔV BE =2R1 / R2 kT / q ln J1 / J2 to compensate V BE However, this solution can only achieve a temperature coefficient of 10ppm / ℃. In the entire temperature range, the output voltage still changes greatly, which is difficult to meet the needs of high-precision measurement. In order to continue to compensate V BE The remaining high-order quantities can achieve a lower temperature coefficient. Researchers have proposed various schemes, such as segmented compensation and exponential compensation. For simple first-order compensation schemes, it is impossible to achieve a reference voltage with a lower temperature coefficient and cannot be used in high-precision application scenarios. Although the existing high-order compensation schemes achieve a lower temperature coefficient, the circuit structure is complex and the power consumption is high.

[0003] Therefore, it is necessary to improve the compensation method of the reference voltage source. Summary of the invention

[0004] In view of the above problems, the present invention provides a reference voltage source circuit for high-order compensation based on the forward current gain temperature characteristic of a BJT, including a CTAT circuit and a PTAT circuit. The CTAT circuit includes a first BJT, the emitter of the first BJTQ1 is connected to the PTAT circuit, the collector of the first BJTQ1 is connected to the base and to a common ground, the PTAT circuit includes a second BJTQ2, the current density ratio of the first BJTQ1 to the second BJTQ2 is 1:N, the collector of the second BJTQ2 is connected to the base and to a common ground, and the reference voltage source circuit is configured to achieve high-order compensation of the reference voltage source circuit by configuring the bias current of the second BJTQ2.

[0005] In the reference voltage source circuit for high-order compensation based on the BJT forward current gain temperature characteristic provided by the present invention, the PTAT circuit also includes a first resistor R1A, a second resistor R1B, a third resistor R2, a fourth resistor R3, an operational amplifier EA1 and a MOS tube M1, the emitter of the second BJTQ2 is connected to the second end of the third resistor R2, the collector of the second BJTQ2 is connected to the base and connected to a common ground, the first end of the third resistor R2 is connected to the second end of the second resistor R1B and the inverting input end of the operational amplifier EA1, the emitter of the first BJTQ1 is connected to the non-inverting input end of the operational amplifier EA1 and the second end of the first resistor R1A, the first ends of the first resistor R1A and the second resistor R2A are connected to the second end of the fourth resistor R3, the output end of the operational amplifier EA1 is connected to the source of the MOS tube M1, the gate of the MOS tube is connected to the power supply VCC, and the drain of the MOS tube is connected to the first end of the fourth resistor R3.

[0006] In the reference voltage source circuit for high-order compensation based on the BJT forward current gain temperature characteristic provided by the present invention, the third resistor R2 is an adjustable resistor, which is used to adjust the bias current of the second BJTQ2.

[0007] In the reference voltage source circuit for high-order compensation based on the BJT forward current gain temperature characteristic provided by the present invention, the reference voltage source circuit has a reference voltage V BG =V BE1 +ΔV BE *R2 / (2R3+R1), where V BE1 =V T ln(I C1 / I S ), ΔV BE =V T (lnN+ln(I E -I E / (β1+1)) / (I E -I E / (β2+1))), R1 is the resistance value of the first resistor R1A and the second resistor R1B, V BE1 is the base-emitter voltage of the first BJT Q1, V T is the thermal voltage, I C1 is the collector current of the first BJT Q1, I S is the saturation current, I E is the emitter current, β1 is the current gain of the first BJT Q1, and β2 is the current gain of the second BJT Q2.

[0008] In the reference voltage source circuit for high-order compensation based on the BJT forward current gain temperature characteristic provided by the present invention, the resistance value of the fourth resistor R3 is adjustable.

[0009] In order to achieve the above-mentioned purpose of the invention, the present invention also provides a high-order compensation method for a reference voltage source circuit, which is applied to the reference voltage source circuit described above for high-order compensation. Based on the BJT forward current gain temperature characteristics, high-order compensation of the reference voltage source is achieved by setting the bias current of the second BJTQ2.

[0010] In order to achieve the above-mentioned invention object, the present invention also provides a high-order compensation method for a reference voltage source circuit, which is applied to the reference voltage source circuit described above for high-order compensation, comprising the steps of: configuring the reference voltage of the reference voltage source circuit to: V BG =V BE1 +ΔV BE *R2 / (2R3+R1), where V BE1 =V T ln(I C1 / I S ), ΔV BE =V T (lnN+ln(I E -I E / (β1+1)) / (I E -I E / (β2+1))), R1 is the resistance value of the first resistor R1A and the second resistor R1B, VB E1 is the base-emitter voltage of the first BJT Q1, V T is the thermal voltage, I C1 is the collector current of the first BJT Q1, I S is the saturation current, I E is the emitter current, β1 is the current gain of the first BJT Q1, and β2 is the current gain of the second BJT Q2.

[0011] The high-order compensation method of the reference voltage source circuit provided by the present invention comprises the steps of:

[0012] The resistance value of the third resistor R2 is set so that the output voltage / reference voltage of the reference voltage source circuit has equal voltage values ​​at at least three temperature points within a preset temperature range.

[0013] In order to achieve the above-mentioned object of the invention, the present invention further provides a chip, which uses the reference voltage source circuit described above, or a high-order compensation method for the reference voltage source circuit.

[0014] The reference voltage source circuit and compensation method thereof provided by the present invention realize the effect of high-order compensation based on the circuit architecture of first-order compensation, which not only saves power consumption and cost, but also can be applied to applications with high precision and wide temperature range, and therefore has extremely high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The invention is a circuit structure diagram of a reference voltage source circuit realized by first-order compensation in the prior art.

[0016] Figure 2 Schematic diagram of the circuit structure of a reference voltage source circuit provided in an embodiment of the present invention.

[0017] Figure 3 In the embodiment of the present invention, V BE Characteristic curves of temperature change under different bias currents.

[0018] Figure 4 In the embodiment of the present invention, ΔV BE Characteristic curves of temperature change under different bias currents.

[0019] Figure 5 It is a characteristic curve diagram of the reference voltage / output voltage of the reference voltage source circuit changing with temperature under different bias currents in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] PTAT (Proportional to Absolute Temperature) and CTAT (Complementary to Absolute Temperature) are terms that describe the characteristics of a voltage or current that vary with temperature. They are very important when designing temperature compensation circuits and bandgap reference circuits. PTAT (Proportional to Absolute Temperature) means proportional to absolute temperature. This voltage or current increases linearly with increasing temperature. The PTAT characteristic is often used to compensate for voltages or currents that decrease with increasing temperature. In a bandgap reference circuit, the PTAT voltage is used to compensate for a voltage with a CTAT characteristic to produce a reference voltage that is independent of temperature. For example, the voltage output in a temperature sensor is a PTAT characteristic. CTAT (Complementary to Absolute Temperature) means complementary to absolute temperature. This voltage or current decreases linearly with increasing temperature. The CTAT characteristic is often used to describe the forward voltage of a diode or the base-emitter voltage of a transistor. In a bandgap reference circuit, the CTAT voltage is combined with the PTAT voltage to achieve temperature compensation. The bandgap reference circuit produces a temperature-stable reference voltage by combining the PTAT and CTAT voltages. Through a certain circuit structure (for example, two diodes or transistors with different current densities), a PTAT voltage can be generated. Combining PTAT and CTAT voltages: Through appropriate circuit design, the PTAT and CTAT voltages are combined in a certain ratio to offset the effects of temperature changes, thereby obtaining a temperature-stable reference voltage.

[0022] In the bandgap reference circuit, first-order compensation and higher-order compensation are technologies used for temperature compensation to ensure that the reference voltage remains stable at different temperatures. First-order compensation refers to eliminating the first-order effect of the reference voltage changing with temperature, that is, linear change, through a simple temperature compensation technique. The first-order compensation method adopted in this embodiment is to combine the PTAT (Proportional to Absolute Temperature, proportional to temperature) voltage and the CTAT (Complementary to Absolute Temperature, temperature complementary) voltage in the circuit to minimize the temperature coefficient. By combining the PTAT and CTAT voltages in appropriate proportions, their temperature changes cancel each other out, thereby obtaining a reference voltage with a temperature coefficient close to zero. This compensation can effectively reduce the linear temperature change of the reference voltage. Higher-order compensation in the prior art refers to further eliminating the second-order and higher-order effects of the reference voltage changing with temperature, that is, nonlinear changes, on the basis of first-order compensation through more complex circuits and technologies. High-order compensation can keep the reference voltage more accurate over a wider temperature range. More complex circuit structure: adding active or passive components in the circuit, such as resistors, capacitors, operational amplifiers, etc., to achieve more sophisticated temperature compensation, but the hardware cost and power consumption are usually high.

[0023] The specific implementation methods of high-order compensation include:

[0024] Nonlinear compensation: By introducing specific circuit elements, the temperature dependence of the voltage conforms to a high-order polynomial, thereby compensating for nonlinear changes.

[0025] Multi-level compensation: Use different compensation mechanisms in different temperature ranges to adapt to a wider temperature range.

[0026] Specific circuit designs may use advanced technologies in analog integrated circuits, such as temperature sensors, digital control circuits, etc., to achieve higher-order compensation effects.

[0027] In traditional concepts, first-order compensation mainly eliminates the linear temperature change of the reference voltage and is suitable for applications with a narrow temperature range.

[0028] High-order compensation: Further eliminates nonlinear temperature variations of the reference voltage, using more complex circuits and techniques, for applications requiring high accuracy and a wide temperature range.

[0029] The reference voltage source circuit and compensation method thereof provided in this embodiment realize the effect of high-order compensation based on the circuit architecture of first-order compensation, which not only saves power consumption and cost, but also can be applied to applications with high precision and wide temperature range, and therefore has extremely high practical value.

[0030] Specifically, an embodiment of the present invention provides a high-order compensation reference voltage source circuit based on the BJT forward current gain temperature characteristic, such as Figure 2 As shown, it includes a CTAT circuit 01 and a PTAT circuit 02. The CTAT circuit 01 includes a first BJTQ1, the emitter of the first BJTQ1 is connected to the compensation circuit 02, the collector of the first BJTQ1 is connected to the base and connected to a common ground, the PTAT circuit 02 includes a second BJTQ2, a first resistor R1A, a second resistor R1B, a third resistor R2, a fourth resistor R3, an operational amplifier EA1 and a MOS tube M1, the emitter of the second BJTQ2 is connected to the second end of the third resistor R2, the collector of the second BJTQ2 is connected to the base and connected to a common ground, and the third resistor R The first end of the first BJT Q2 is connected to the second end of the second resistor R1B and the inverting input end of the operational amplifier EA1, the emitter of the first BJT Q1 is connected to the non-inverting input end of the operational amplifier EA1 and the second end of the first resistor R1A, the first ends of the first resistor R1A and the second resistor R2A are connected to the second end of the fourth resistor R3, the output end of the operational amplifier EA1 is connected to the source of the MOS tube M1, the gate of the MOS tube is connected to the power supply VCC, the drain of the MOS tube is connected to the first end of the fourth resistor R3, and form the output end of the PTAT circuit 02, that is, the output end of the reference voltage source circuit.

[0031] The current density ratio of the first BJT Q1 and the second BJT Q2 is 1:N. Specifically, N can be selected based on actual scenarios, such as 8.

[0032] The IV characteristic of a diode-connected BJT is V BE =V T ln(I C / I S ), where I S is the saturation current, I C is the collector current, I B is the base current, I E is the emitter current, V T is the thermal voltage, specifically, V T = kT / q, then Figure 1 The V of the first BJTQ1 and the second BJTQ2 BE The expressions are: V BE1 =V T ln(I C1 / Is ), V BE2 =V T ln(I C2 / N*I s );then:ΔV BE =V T ln(IC1 / I S )-V T ln(I C2 / N*I S )=V T (I C1 / I S -I C2 / N*I S ).

[0033] byI E =I C +I B , β=I C / I B , we can get I B =I E / (1+β), corresponding to the first BJTQ1 and the second BJTQ2, I C1 =I E -I B1 =I E -I E / (β1+1),I C2 =I E -I B2 =I E -I E / (β2+1), substituting into the above formula we get:

[0034] ΔVB E =VT(lnN+ln(I E -I E / (β1+1)) / (I E -I E / (β2+1)))

[0035] The current gain of a BJT varies with the collector current (I c ). In addition, β also changes with temperature β∝e -1 / T In general, β is a function of collector current and temperature, β = f(I C ,T). Since the current density of the first BJTQ1 and the second BJTQ2 is different, resulting in different β, a high-order compensation term is introduced: ln(I E -I E / (β1+1)) / (I E -I E / (β2+1)), this term can be used to compensate for V BE In this way, high-order compensation effect is achieved without adding additional circuits.

[0036] The reference voltage source circuit provided in this embodiment realizes the effect of high-order compensation based on the circuit architecture of first-order compensation, which not only saves power consumption and cost, but also can be applied to applications with high precision and wide temperature range, and therefore has extremely high practical value.

[0037] At this time, the reference voltage V BG =V BE1 +ΔV BE *R2 / (2R3+R1).

[0038] The resistance values ​​of the first resistor R1A and the second resistor R1B are both R1. The first resistor to the fourth resistor are used to set the current and voltage distribution to ensure that the circuit works at the required operating point. BE1 is the CTAT voltage, such as Figure 3 As shown in the figure, under different bias currents, the waveform changes nonlinearly with temperature, ΔV BE is the PTAT voltage, such as Figure 4 As shown, under different bias currents, the waveform changes nonlinearly with temperature. In this embodiment, by generating and combining PTAT and CTAT voltages, high-order compensation is achieved to generate a stable reference voltage.

[0039] Specifically, due to ΔV BE The nonlinearity of is related to the forward current gain β. Different bias currents correspond to different β. Therefore, ΔV can be adjusted by adjusting the bias current value. BE The nonlinear size of Figure 1 The circuit structure in can adjust the value of the third resistor R2 to adjust the bias current of the second BJTQ2 and obtain the required high-order compensation amount. Figure 5 The curves marked with circles and squares are under-compensated or over-compensated reference voltages, and the curve marked with stars is a reference voltage obtained based on the "required high-order compensation amount". The reference voltage is characterized in that there are three temperature points with equal voltage values. The reference voltage with appropriate high-order compensation can be obtained by the size of the third resistor R2. Based on this, the third resistor R2 can be set as an adjustable resistor.

[0040] Optionally, the fourth resistor R3 may also be set as an adjustable resistor to calibrate the deviation of the PTAT voltage caused by resistor or transistor mismatch.

[0041] Optionally, this embodiment provides a high-order compensation method for a reference voltage source circuit, which implements high-order compensation for the reference voltage source by setting the bias current of the second BJT Q2 based on the BJT forward current gain temperature characteristic.

[0042] Optionally, the high-order compensation method further includes setting the resistance of the third resistor R2 so that the output voltage / reference voltage of the reference voltage source circuit has equal voltage values ​​at at least three temperature points within a preset temperature range.

[0043] Optionally, this embodiment further provides a chip, applying the reference voltage source circuit described above, or a high-order compensation method of the reference voltage source circuit.

[0044] So far, the technical solution of the present invention has been described in conjunction with the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to the above-mentioned specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A reference voltage source circuit for high-order compensation based on BJT forward current gain temperature characteristics, characterized in that: It includes a CTAT circuit and a PTAT circuit, the CTAT circuit includes a first BJT, the emitter of the first BJTQ1 is connected to the PTAT circuit, the collector of the first BJTQ1 is connected to the base and connected to a common ground, the PTAT circuit includes a second BJTQ2, the current density ratio of the first BJTQ1 and the second BJTQ2 is 1:N, the collector of the second BJTQ2 is connected to the base and connected to a common ground, and the reference voltage source circuit is configured to achieve high-order compensation of the reference voltage source circuit by configuring the bias current of the second BJTQ2.

2. The reference voltage source circuit for high-order compensation based on BJT forward current gain temperature characteristics according to claim 1, characterized in that: The PTAT circuit also includes a first resistor R1A, a second resistor R1B, a third resistor R2, a fourth resistor R3, an operational amplifier EA1 and a MOS tube M1, the emitter of the second BJTQ2 is connected to the second end of the third resistor R2, the collector of the second BJTQ2 is connected to the base and to a common ground, the first end of the third resistor R2 is connected to the second end of the second resistor R1B and the inverting input end of the operational amplifier EA1, the emitter of the first BJTQ1 is connected to the non-inverting input end of the operational amplifier EA1 and the second end of the first resistor R1A, the first ends of the first resistor R1A and the second resistor R2A are connected to the second end of the fourth resistor R3, the output end of the operational amplifier EA1 is connected to the source of the MOS tube M1, the gate of the MOS tube is connected to the power supply VCC, and the drain of the MOS tube is connected to the first end of the fourth resistor R3.

3. The reference voltage source circuit for high-order compensation based on BJT forward current gain temperature characteristics according to claim 2, characterized in that: The third resistor R2 is an adjustable resistor, which is used to adjust the bias current of the second BJT Q2.

4. The reference voltage source circuit for high-order compensation based on BJT forward current gain temperature characteristics according to claim 2 or 3, characterized in that: The reference voltage V of the reference voltage source circuit BG =V BE1 +ΔV BE *R2 / (2R3+R1), where V BE1 =V T ln(I C1 / I S ), ΔV BE =V T (lnN+ln(I E -I E / (β1+1)) / (I E -I E / (β2+1))), R1 is the resistance value of the first resistor R1A and the second resistor R1B, V BE1 is the base-emitter voltage of the first BJT Q1, V T is the thermal voltage, I C1 is the collector current of the first BJT Q1, I S is the saturation current, I E is the emitter current, β1 is the current gain of the first BJT Q1, and β2 is the current gain of the second BJT Q2.

5. The reference voltage source circuit for high-order compensation based on BJT forward current gain temperature characteristics according to claim 2 or 3, characterized in that: The resistance of the fourth resistor R3 is adjustable.

6. A high-order compensation method for a reference voltage source circuit, applied to perform high-order compensation on the reference voltage source circuit according to any one of claims 1 to 5, characterized in that: Based on the BJT forward current gain temperature characteristic, high-order compensation of the reference voltage source is achieved by setting the bias current of the second BJT Q2.

7. A high-order compensation method for a reference voltage source circuit, applied to perform high-order compensation on the reference voltage source circuit according to any one of claims 2 to 5, characterized in that: The steps include: configuring the reference voltage of the reference voltage source circuit to: V BG =V BE1 +ΔV BE *R2 / (2R3+R1), where V BE1 =V T ln(I C1 / I S ), ΔV BE =V T (lnN+ln(I E -I E / (β1+1)) / (I E -I E / (β2+1))), R1 is the resistance value of the first resistor R1A and the second resistor R1B, V BE1 is the base-emitter voltage of the first BJT Q1, V T is the thermal voltage, I C1 is the collector current of the first BJT Q1, I S is the saturation current, I E is the emitter current, β1 is the current gain of the first BJT Q1, and β2 is the current gain of the second BJT Q2.

8. The high-order compensation method for a reference voltage source circuit according to claim 6, characterized in that: Includes steps: The resistance value of the third resistor R2 is set so that the output voltage / reference voltage of the reference voltage source circuit has equal voltage values ​​at at least three temperature points within a preset temperature range.

9. A chip, characterized in that: A reference voltage source circuit as described in any one of claims 1 to 5, or a high-order compensation method for a reference voltage source circuit as described in any one of claims 6 to 8 is applied.

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