CN115586809A - Exponential type temperature compensation band gap reference voltage source and compensation method thereof - Google Patents
Exponential type temperature compensation band gap reference voltage source and compensation method thereof Download PDFInfo
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Abstract
An exponential temperature compensation band gap reference voltage source and a compensation method thereof comprise the following steps: the starting circuit starts the PTAT generating circuit; the PTAT generating circuit generates a first current based on a difference value of base-emitter voltages of the first triode and the second triode; the first current forms a second current in the summing output circuit, and the first current forms a third current in the exponential compensation circuit; the exponential compensation circuit generates a fourth current based on the first current and the relationship between the current amplification factor and the temperature of the third triode; the summing output circuit generates a reference voltage by using a voltage formed by the second current on one resistor, a voltage formed by the difference value of the second current and the fourth current on the other resistor and a base-emitter voltage of a fourth triode; the fourth current is an exponential temperature coefficient current. The invention utilizes the exponential relation between the current amplification factor of the triode and the temperature and carries out curvature compensation with a high-order nonlinear term in the base electrode-emitter voltage, thereby achieving low temperature drift.
Description
Technical Field
The invention belongs to the technical field of power management, and particularly relates to an exponential temperature compensation band gap reference voltage source and a compensation method thereof.
Background
The bandgap reference circuit is an essential part of an electronic circuit, and includes Analog devices such as an ADC (Analog to Digital Converter), a DAC (Digital to Analog Converter), a linear regulator module, and an indispensable module in a plurality of Digital-Analog hybrid circuits, and because the index requirements of these circuits are increasing, the bandgap reference circuit also has higher requirements. The traditional band-gap reference circuit utilizes the characteristic that the voltage difference between two emitting junctions with different emitting junction areas has a positive temperature coefficient to perform weighted summation with base-emitter voltage with a negative temperature coefficient to obtain reference voltage with a low temperature coefficient.
The band-gap reference circuit has the greatest characteristic that the output reference voltage can not change greatly along with the wide-range change of the temperature, namely low temperature drift. In the prior art, a bandgap reference circuit realizes compensation of a first-order temperature coefficient, an operational amplifier is used in the circuit to realize smaller temperature drift, but the base-emitter voltage V is ignored BE The high-order term in the middle, therefore, the traditional bandgap reference circuit adopting the first-order temperature compensation still has a relatively high temperature drift. Based on the shortcomings of the conventional bandgap reference circuit, the bandgap reference circuit has started to adopt various high-order temperature compensation methods to further reduce the temperature drift. In 1983, gray et al proposed a square curvature compensation technique, in 1994, inyeol Lee et al proposed an exponential temperature compensation mode, and in 1998, allen et al proposed a piecewise linear compensation mode. However, the current in the output circuit in the existing exponential temperature compensation mode is not accurate enough due to the influence of the base current of other triodes, so that the compensation of the first-order term and the compensation of the exponential term cannot be separated from each other, therefore, the compensation effect is not ideal enough, the temperature drift suppression effect is not ideal enough, and the output reference voltage has 2mV voltage deviation within the range of minus 40 ℃ to 125 ℃.
Disclosure of Invention
The invention provides an exponential temperature compensation band gap reference voltage source and a compensation method thereof, aiming at solving the defects in the prior art.
The invention adopts the following technical scheme.
The invention provides an exponential temperature compensation band gap reference voltage source on the one hand, and the band gap reference voltage source comprises: the circuit comprises a starting circuit, a PTAT generating circuit, an index compensating circuit and a summation output circuit; the PTAT generating circuit comprises a first triode and a second triode, the index compensation circuit comprises a third triode, and the summing output circuit comprises a fourth triode and two resistors;
a start-up circuit for starting up the PTAT generating circuit; a PTAT generating circuit for generating a first current based on a difference between a base-emitter voltage of the first transistor and a base-emitter voltage of the second transistor; the first current forms a second current in the summing output circuit, and the first current forms a third current in the exponential compensation circuit; the exponential compensation circuit is used for generating a fourth current based on the relationship between the first current and the current amplification factor and the temperature of the third triode; a summing output circuit for generating a reference voltage using a voltage formed at one resistor by the second current, a voltage formed at the other resistor by a difference between the second current and the fourth current, and a base-emitter voltage of the fourth transistor;
wherein the first current is a current proportional to absolute temperature, and the fourth current is a current of exponential temperature coefficient.
The PTAT generating circuit includes: the MOS transistor comprises a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a first triode, a second triode and a first resistor; the PTAT generating circuit is connected with the output end of the starting circuit through the drain electrode of the first MOS tube;
the source electrodes of the first MOS tube and the second MOS tube are both connected with a reference voltage VDD, the grid electrode of the first MOS tube is connected with the grid electrode of the second MOS tube, the drain electrode of the first MOS tube is connected with the drain electrode of the third MOS tube, the drain electrode of the second MOS tube is in short circuit with the grid electrode, the grid electrode of the third MOS tube is in short circuit with the drain electrode, the grid electrode of the third MOS tube is connected with the grid electrode of the fourth MOS tube, the source electrode of the third MOS tube is connected with the emitting electrode of the first triode, the drain electrode of the fourth MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the fourth MOS tube is connected with one end of a first resistor, the other end of the first resistor is connected with the emitting electrode of the second triode, and the base electrodes and the collector electrodes of the first triode and the second triode are both grounded;
a first current flows through the first resistor.
The width-length ratio of the first MOS tube and the second MOS tube is the same.
The exponent compensating circuit includes: a fifth MOS tube, a sixth MOS tube, a seventh MOS tube and a third triode; the index compensation circuit is connected with the grids of the first MOS tube and the second MOS tube through the grid of the fifth MOS tube;
a source electrode of the fifth MOS tube and a collector electrode of the third triode are both connected with a reference voltage VDD, a drain electrode of the fifth MOS tube is connected with a drain electrode of the sixth MOS tube, a grid electrode and a drain electrode of the sixth MOS tube are in short circuit, the sixth MOS tube and the seventh MOS tube form a current mirror form, a drain electrode of the seventh MOS tube is connected with an emitter electrode of the third triode, and a base electrode of the third triode is connected with an input end of a summing output circuit; the source electrodes of the sixth MOS tube and the seventh MOS tube are grounded;
after the first current flows into the exponential compensation circuit, a third current proportional to the first current flows through an emitter of the third triode, and the third current generates a fourth current at a base of the third triode.
The start-up circuit includes: an eighth MOS tube, a ninth MOS tube and a capacitor; the source electrodes of the eighth MOS tube and the ninth MOS tube are both connected with a reference voltage VDD, the grid electrode and the drain electrode of the eighth MOS tube are in short circuit, the grid electrode of the ninth MOS tube is connected with the drain electrode of the eighth MOS tube, and the drain electrode of the ninth MOS tube is connected with the drain electrode of the first MOS tube and the drain electrode of the third MOS tube; one end of the capacitor is connected with the drain electrode of the first MOS tube, and the other end of the capacitor is grounded.
The summing output circuit includes: a tenth MOS tube, a fourth triode, a second resistor and a third resistor; one end of the second resistor and one end of the third resistor are both connected with the base electrode of the third triode;
a source electrode of the tenth MOS tube is connected with a reference voltage VDD, a grid electrode of the tenth MOS tube is connected with a grid electrode of the first MOS tube, a drain electrode of the tenth MOS tube is connected with the other end of the third resistor, the other end of the second resistor is connected with an emitting electrode of the fourth triode, and a base electrode and a collector electrode of the fourth triode are grounded; the drain electrode of the tenth MOS tube outputs reference voltage;
a second current flows through the third resistor.
The invention also provides a compensation method for compensating the band gap reference voltage source by using the exponential temperature, which comprises the following steps:
step 1, starting a capacitor in a circuit to charge at the moment when the circuit is accessed to a reference voltage; the starting circuit enables the PTAT generating circuit to be conducted and started;
in the PTAT generating circuit, the current flowing through the collector electrode of the first triode is equal to the current flowing through the collector electrode of the second triode, and under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, a voltage difference value between the base electrode-emitter voltage of the first triode and the base electrode-emitter voltage of the second triode generates a first current on the first resistor;
step 3, extracting a high-order term from the nonlinear term of the base electrode-emitter voltage of the third triode;
calculating to obtain a second current according to the high-order term and a first proportional coefficient of the first current, wherein the first proportional coefficient is a shunt proportional coefficient of the first current passing through the second MOS tube and the tenth MOS tube;
calculating to obtain a third current according to the high-order term and a second proportional coefficient of the first current, wherein the second proportional coefficient is a shunt proportional coefficient of the first current passing through a second MOS tube, a fifth MOS tube, a sixth MOS tube and a seventh MOS tube;
step 4, calculating a fourth current generated by the third current at the base electrode of the third triode based on the relation between the current amplification factor of the third triode and the temperature;
and 5, calculating to obtain reference voltage by using the base-emitter voltage, the second resistor, the third resistor, the second current and the fourth current of the fourth triode according to the following relational expression:
V REF ＝V BE4 +I 2 R 3 +(I 2 -I 4 )R 2
in the formula (I), the compound is shown in the specification,
V REF is a reference voltage to be used as a reference voltage,
V BE4 is the base of the fourth triode-the voltage of the emitter(s),
I 2 is the second current, and is the second current,
I 4 is the fourth current, and is the fourth current,
R 2 is the resistance value of the second resistor, and is,
R 3 is the third resistance value;
step 6, fourth current I 4 By T
For compensating the term, by adjusting the first proportionality coefficient K 1 A second proportionality coefficient K 2 The resistance value of the first resistor, the resistance value of the second resistor and the resistance value of the third resistor enable the temperature drift of the output reference voltage to be zero; wherein, delta E G K is the boltzmann constant, and T is the temperature, which is the silicon bandgap reduction factor.
Preferably, step 1 comprises:
step 1.1, when the circuit is connected to a reference voltage, the eighth MOS tube is connected into a diode connection mode, and the capacitor starts to charge;
step 1.2, the ninth MOS tube is conducted to form a current path from the reference voltage VDD to the ground through the ninth MOS tube, the third MOS tube and the first triode, and the PTAT generating circuit is conducted;
1.3, other circuit elements in the PTAT generating circuit are separated from a zero degeneracy state;
and 1.4, after the current in the PTAT generating circuit is stable, charging a capacitor in the starting circuit to a high level, so that the eighth MOS transistor and the ninth MOS transistor are both turned off, and the starting of the PTAT generating circuit is finished.
Preferably, in step 2, the base-emitter voltage V of the first triode BE1 The following relation is satisfied:
base-emitter voltage V of the second triode BE2 Satisfies the following relation:
in the formula (I), the compound is shown in the specification,
V T is thermal voltage, 26mV at normal temperature,
I C1 in order to flow the collector current of the first transistor,
I C2 for a collector current to flow through the second transistor,
I S1 for reverse saturation current flowing through the emitter junction of the first transistor,
I S2 is a reverse saturation current flowing through the emitter junction of the first triode;
under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, I C1 ＝I C2 。
Preferably, the current I flowing through the first resistor 1 The following relation is satisfied:
in the formula (I), the compound is shown in the specification,
R 1 is the resistance value of the first resistor, and is,
and N is the ratio of the emitter junction areas of the second triode and the first triode.
Preferably, in step 3, the non-linear term of the base-emitter voltage of the slave transistor satisfies the following relation:
in the formula (I), the compound is shown in the specification,
V REF (T) is a band gap reference voltage at a temperature T,
V G is a reference temperature T r The band-gap voltage of the lower silicon,
t is the temperature of the molten metal,
T r as a reference temperature for the purpose of the temperature,
V BE (T r ) To be at a reference temperature T r The lower base-emitter voltage is set to be,
eta is an exponential coefficient of electron mobility in silicon with temperature,
q is the electron charge amount;
when reference temperature T r Being constant, the non-linear term, T ln (T), is the higher order term to be compensated.
Preferably, the second current I is calculated according to the higher-order term and the first proportional coefficient of the first current 2 The following relational expression is satisfied:
in the formula (I), the compound is shown in the specification,
K 1 is a first scale factor and is a ratio of,
k is the boltzmann constant.
Preferably, the third current I is calculated according to the high-order term and the second proportionality coefficient of the first current 3 The following relational expression is satisfied:
in the formula (I), the compound is shown in the specification,
K 2 is a second scaling factor to be used for the second scaling factor,
k is the boltzmann constant.
Preferably, in step 4, the third current generates a fourth current I at the base of the third triode 4 The following relational expression is satisfied:
wherein, beta (T) is the relation between the current amplification factor of the third triode and the temperature.
Preferably, β (T) satisfies the following relation:
in the formula (I), the compound is shown in the specification,
β ∞ is a constant fitted to beta (T) with temperature change,
ΔE G is the silicon bandgap reduction factor.
The exponential temperature compensation band gap reference voltage source has the advantages that compared with the prior art, the exponential temperature compensation circuit is simple in structure, only one triode base current which is in an exponential relation with temperature is added in an output branch circuit, an exponential nonlinear term is introduced into output voltage, a reference voltage with small temperature drift is obtained by adjusting relevant parameters in the circuit, the maximum deviation of the reference voltage within the range of minus 40-125 ℃ is only 0.5mV, the reference voltage has small temperature drift coefficients and very good temperature characteristics, and the exponential temperature compensation band gap reference voltage source can be used in numerous occasions with high requirements for temperature drift.
The invention is improved on the basis of a first-order band gap reference circuit, better fresh fruits can be obtained without using an operational amplifier, and a better temperature drift inhibition effect can be achieved if the operational amplifier is used.
The MOSFET and the BJT used in the circuit provided by the invention are integratable devices, so the whole circuit can be integrated on a chip, and the occupied area is smaller.
In addition, the circuit provided by the invention only needs to adjust the width-length ratio of the MOSFET to change the parameters of the output voltage, so that the output voltage reaches smaller temperature drift, and the circuit is convenient to adjust, flexible to operate and high in feasibility. Therefore, the circuit has the obvious advantages of good effect, simple structure, small area and simple adjustment mode.
Drawings
FIG. 1 is a circuit diagram of an exponential temperature compensated bandgap reference voltage source according to the present invention;
the reference numerals in fig. 1 are explained as follows:
MP 1-first MOS tube, MP 2-second MOS tube, MN 1-third MOS tube, MN 2-fourth MOS tube, MP 3-fifth MOS tube, MN 3-sixth MOS tube, MN 4-seventh MOS tube, MP 4-eighth MOS tube, MP 5-ninth MOS tube, MP 6-tenth MOS tube, VDD-reference voltage, C-capacitor, R1-first resistor, R2-second resistor, R3-third resistor, i 1-first current, i 2-second current, i 3-third current, i 4-fourth current, GND-ground, Q1-first triode, Q2-second triode, Q3-third triode, Q4-fourth triode, vref-reference voltage, 100-start circuit, 200-PTAT generating circuit, 300-exponential compensation circuit, 400-summation output circuit;
FIG. 2 is a graph of the output of an embodiment of the present invention without exponential temperature compensation;
FIG. 3 is a diagram of the output result of the exponential temperature compensated bandgap reference voltage source according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described herein are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by a person skilled in the art without making any inventive step on the basis of the spirit of the present invention are within the scope of protection of the present invention.
The invention provides an exponential temperature compensation band gap reference voltage source on the one hand, and the band gap reference voltage source comprises: a start-up circuit 100, a PTAT generating circuit 200, an index compensating circuit 300, a summing output circuit 400; the PTAT generating circuit comprises a first triode Q1 and a second triode Q2, the index compensation circuit comprises a third triode Q3, and the summing output circuit comprises a fourth triode Q4 and two resistors;
a start-up circuit for starting up the PTAT generating circuit; a PTAT generating circuit for generating a first current based on a difference between a base-emitter voltage of the first triode and a base-emitter voltage of the second triode; the first current forms a second current in the summing output circuit, and the first current forms a third current in the exponential compensation circuit; the exponential compensation circuit is used for generating a fourth current based on the relationship between the first current and the current amplification factor and the temperature of the third triode; a summing output circuit for generating a reference voltage using a voltage formed at one resistor by the second current, a voltage formed at the other resistor by a difference between the second current and the fourth current, and a base-emitter voltage of the fourth transistor;
wherein the first current is a current proportional to absolute temperature, and the fourth current is a current of exponential temperature coefficient.
The PTAT generating circuit includes: the MOS transistor comprises a first MOS transistor MP1, a second MOS transistor MP2, a third MOS transistor MN1, a fourth MOS transistor MN2, a first triode Q1, a second triode Q2 and a first resistor R1; the PTAT generating circuit is connected with the output end of the starting circuit through the drain electrode of the first MOS tube;
the source electrodes of the first MOS tube and the second MOS tube are both connected with a reference voltage VDD, the grid electrode of the first MOS tube is connected with the grid electrode of the second MOS tube, the drain electrode of the first MOS tube is connected with the drain electrode of the third MOS tube, the drain electrode of the second MOS tube is in short circuit with the grid electrode, the grid electrode of the third MOS tube is in short circuit with the drain electrode, the grid electrode of the third MOS tube is connected with the grid electrode of the fourth MOS tube, the source electrode of the third MOS tube is connected with the emitting electrode of the first triode, the drain electrode of the fourth MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the fourth MOS tube is connected with one end of a first resistor, the other end of the first resistor is connected with the emitting electrode of the second triode, and the base electrodes and the collector electrodes of the first triode and the second triode are both grounded;
a first current i1 flows through the first resistor.
The width-length ratio of the first MOS tube and the second MOS tube is the same.
The exponent compensating circuit includes: a fifth MOS transistor MP3, a sixth MOS transistor MN3, a seventh MOS transistor MN4, and a third triode Q3; the index compensation circuit is connected with the grids of the first MOS tube and the second MOS tube through the grid of the fifth MOS tube;
a source electrode of the fifth MOS tube and a collector electrode of the third triode are both connected with a reference voltage VDD, a drain electrode of the fifth MOS tube is connected with a drain electrode of the sixth MOS tube, a grid electrode and a drain electrode of the sixth MOS tube are in short circuit, the sixth MOS tube and the seventh MOS tube form a current mirror form, a drain electrode of the seventh MOS tube is connected with an emitter electrode of the third triode, and a base electrode of the third triode is connected with an input end of a summing output circuit; the source electrodes of the sixth MOS tube and the seventh MOS tube are grounded;
after the first current flows into the exponential compensation circuit, a third current i3 proportional to the first current flows through an emitter of the third triode, and the third current generates a fourth current i4 at a base of the third triode.
The start-up circuit includes: an eighth MOS transistor MP4, a ninth MOS transistor MP5 and a capacitor; the source electrodes of the eighth MOS tube and the ninth MOS tube are both connected with a reference voltage VDD, the grid electrode and the drain electrode of the eighth MOS tube are in short circuit, the grid electrode of the ninth MOS tube is connected with the drain electrode of the eighth MOS tube, and the drain electrode of the ninth MOS tube is connected with the drain electrode of the first MOS tube and the drain electrode of the third MOS tube; one end of the capacitor is connected with the drain electrode of the first MOS tube, and the other end of the capacitor is grounded.
The summing output circuit includes: a tenth MOS transistor MP6, a fourth triode Q4, a second resistor R2, and a third resistor R3; one end of the second resistor and one end of the third resistor are both connected with the base electrode of the third triode;
a source electrode of the tenth MOS tube is connected with a reference voltage VDD, a grid electrode of the tenth MOS tube is connected with a grid electrode of the first MOS tube, a drain electrode of the tenth MOS tube is connected with the other end of the third resistor, the other end of the second resistor is connected with an emitting electrode of the fourth triode, and a base electrode and a collector electrode of the fourth triode are grounded; the drain electrode of the tenth MOS tube outputs reference voltage;
a second current i2 flows through the third resistor. In the summing output circuit, exponential type compensation current flows through the third resistor, and no current flows through the second resistor, so that the current in the circuit is more accurate, and the influence of base currents of other triodes is completely avoided. The compensation of the first order term and the compensation of the exponential term can be separated and relatively independent, so that the adjustment of the circuit is simple.
The invention also provides a compensation method for compensating the band gap reference voltage source by using the exponential temperature, which comprises the following steps:
step 1, starting a capacitor in a circuit to charge at the moment when the circuit is connected to a reference voltage; the start-up circuit causes the PTAT generating circuit to conduct for start-up.
Specifically, step 1 comprises:
step 1.1, when the circuit is connected to a reference voltage, the eighth MOS tube is connected into a diode connection mode, and the capacitor starts to charge;
step 1.2, the ninth MOS tube is conducted to form a current path from the reference voltage VDD to the ground through the ninth MOS tube, the third MOS tube and the first triode, and the PTAT generating circuit is conducted;
1.3, other circuit elements in the PTAT generating circuit are separated from a zero degeneracy state;
and 1.4, after the current in the PTAT generating circuit is stable, charging a capacitor in the starting circuit to a high level, so that the eighth MOS transistor and the ninth MOS transistor are both turned off, and the starting of the PTAT generating circuit is finished.
In the PTAT generating circuit, the current flowing through the collector electrode of the first triode is equal to the current flowing through the collector electrode of the second triode, and under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, the voltage difference value between the emitter voltage of the base electrode of the first triode and the emitter voltage of the base electrode of the second triode generates a first current on the first resistor.
Specifically, in step 2, the base-emitter voltage V of the first triode BE1 Satisfies the following relation:
base-emitter voltage V of the second triode BE2 The following relation is satisfied:
in the formula (I), the compound is shown in the specification,
V T is thermal voltage, 26mV at normal temperature,
I C1 in order to flow the collector current of the first transistor,
I C2 in order to flow the collector current of the second transistor,
I S1 for reverse saturation of emitter junction flowing through the first triodeThe current is applied to the surface of the substrate,
I S2 is a reverse saturation current flowing through the emitter junction of the first triode;
under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, I C1 ＝I C2 。
Further, a current I flowing through the first resistor 1 Satisfies the following relation:
in the formula (I), the compound is shown in the specification,
R 1 is a resistance value of the first resistor, and is,
and N is the ratio of the emitter junction areas of the second triode and the first triode.
Step 3, extracting a high-order term from the nonlinear term of the base electrode-emitter voltage of the third triode;
calculating to obtain a second current according to the high-order term and a first proportional coefficient of the first current, wherein the first proportional coefficient is a shunt proportional coefficient of the first current passing through the second MOS tube and the tenth MOS tube;
and calculating to obtain a third current according to the high-order term and a second proportional coefficient of the first current, wherein the second proportional coefficient is a shunt proportional coefficient of the first current passing through a second MOS tube, a fifth MOS tube, a sixth MOS tube and a seventh MOS tube.
Specifically, in step 3, the nonlinear term of the base-emitter voltage of the slave triode satisfies the following relation:
in the formula (I), the compound is shown in the specification,
V REF (T) is a band gap reference voltage at a temperature T,
V G is a reference temperature T r The band-gap voltage of the lower silicon,
t is the temperature of the molten metal,
T r for the purpose of the reference temperature, the temperature,
V BE (T r ) To be at a reference temperature T r The lower base-emitter voltage is set to,
eta is an exponential coefficient of electron mobility in silicon with temperature,
q is the electron charge amount;
when reference temperature T r Being constant, the nonlinear term, tln (T), is the higher order term to be compensated.
Further, a second current I is obtained by calculation according to the high-order terms and a first proportional coefficient of the first current 2 And satisfies the following relation:
in the formula (I), the compound is shown in the specification,
K 1 is a first scale factor and is a ratio of,
k is the boltzmann constant.
Further, a third current I is obtained through calculation according to the high-order terms and a second proportional coefficient of the first current 3 The following relational expression is satisfied:
in the formula (I), the compound is shown in the specification,
K 2 is a second scaling factor to be used for the second scaling factor,
k is the boltzmann constant.
And 4, calculating a fourth current generated by the third current at the base electrode of the third triode based on the relation between the current amplification factor of the third triode and the temperature.
Specifically, in step 4, the third current generates a fourth current I at the base of the third transistor 4 The following relational expression is satisfied:
wherein, beta (T) is the relation between the current amplification factor of the third triode and the temperature.
Preferably, β (T) satisfies the following relation:
in the formula (I), the compound is shown in the specification,
β ∞ is a constant fitted to beta (T) with temperature,
ΔE G is the silicon bandgap reduction factor.
And 5, calculating to obtain reference voltage by using the base-emitter voltage, the second resistor, the third resistor, the second current and the fourth current of the fourth triode according to the following relational expression:
V REF ＝V BE +I 2 R 3 +(I 2 -I 4 )R 2
in the formula (I), the compound is shown in the specification,
V REF is a reference voltage to be used as a reference voltage,
V BE is the base-emitter voltage of the fourth transistor,
I 2 is the second current, and is the second current,
I 4 is the third current to be the fourth current,
R 2 is the resistance value of the second resistor, and is,
R 3 is the third resistance value.
Step 6, the fourth current I4 is T
For compensating the term, by adjusting the first proportionality coefficient K 1 A second proportionality coefficient K 2 The resistance value of the first resistor, the resistance value of the second resistor and the resistance value of the third resistor enable the temperature drift of the output reference voltage to be zero; wherein, delta E G K is the boltzmann constant, and T is the temperature.
The exponential temperature compensation band gap reference voltage source has the advantages that compared with the prior art, the exponential temperature compensation circuit is simple in structure, only one triode base current which is in an exponential relation with temperature is added in an output branch circuit, an exponential nonlinear term is introduced into output voltage, a reference voltage with small temperature drift is obtained by adjusting relevant parameters in the circuit, the maximum deviation of the reference voltage within the range of minus 40-125 ℃ is only 0.5mV, the reference voltage has small temperature drift coefficients and very good temperature characteristics, and the exponential temperature compensation band gap reference voltage source can be used in numerous occasions with high requirements for temperature drift.
The invention is improved on the basis of a first-order band gap reference circuit, better fresh fruits can be obtained without using an operational amplifier, and a better temperature drift inhibition effect can be achieved if the operational amplifier is used.
The MOSFET and the BJT used in the circuit provided by the invention are integratable devices, so that the whole circuit can be integrated on a chip, and the occupied area is small.
In addition, the circuit provided by the invention only needs to adjust the width-length ratio of the MOSFET to change the parameters of the output voltage, so that the output voltage reaches smaller temperature drift, and the circuit is convenient to adjust, flexible to operate and high in feasibility. Therefore, the circuit has the obvious advantages of better effect, simple structure, smaller area and simple adjustment mode.
FIG. 2 is a graph corresponding to the reference voltage output by a conventional first-order bandgap reference circuit, and it can be seen that there is a voltage deviation of 2mV in the range of-40 to 125 ℃; FIG. 3 corresponds to the exponentially compensated bandgap reference circuit proposed in this patent, with a reference voltage that is only 0.5mV offset in the range-40 to 125 deg.C. The temperature drift of the output of the band-gap reference circuit is greatly reduced, and the stability of the temperature is greatly improved, so that the circuit can be used in most application occasions.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (15)
1. An exponential temperature compensation band gap reference voltage source is characterized in that:
the band-gap reference voltage source comprises: the starting circuit, the PTAT generating circuit, the index compensating circuit and the summing output circuit; the PTAT generating circuit comprises a first triode and a second triode, the index compensation circuit comprises a third triode, and the summing output circuit comprises a fourth triode and two resistors;
a start-up circuit for starting up the PTAT generating circuit; a PTAT generating circuit for generating a first current based on a difference between a base-emitter voltage of the first triode and a base-emitter voltage of the second triode; the first current forms a second current in the summing output circuit, and the first current forms a third current in the exponential compensation circuit; the exponential compensation circuit is used for generating a fourth current based on the relationship between the first current and the current amplification factor and the temperature of the third triode; a summing output circuit for generating a reference voltage using a voltage formed at one resistor by the second current, a voltage formed at the other resistor by a difference between the second current and the fourth current, and a base-emitter voltage of the fourth transistor;
wherein the first current is a current proportional to absolute temperature, and the fourth current is a current of exponential temperature coefficient.
2. The exponential temperature-compensated bandgap reference voltage source of claim 1, wherein:
the PTAT generating circuit includes: the circuit comprises a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a first triode, a second triode and a first resistor; the PTAT generating circuit is connected with the output end of the starting circuit through the drain electrode of the first MOS tube;
the source electrodes of the first MOS tube and the second MOS tube are both connected with a reference voltage VDD, the grid electrode of the first MOS tube is connected with the grid electrode of the second MOS tube, the drain electrode of the first MOS tube is connected with the drain electrode of the third MOS tube, the drain electrode of the second MOS tube is in short circuit with the grid electrode, the grid electrode of the third MOS tube is in short circuit with the drain electrode, the grid electrode of the third MOS tube is connected with the grid electrode of the fourth MOS tube, the source electrode of the third MOS tube is connected with the emitting electrode of the first triode, the drain electrode of the fourth MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the fourth MOS tube is connected with one end of a first resistor, the other end of the first resistor is connected with the emitting electrode of the second triode, and the base electrodes and the collector electrodes of the first triode and the second triode are both grounded;
a first current flows through the first resistor.
3. The exponential temperature-compensated bandgap reference voltage source of claim 2, wherein:
the width-length ratio of the first MOS tube and the second MOS tube is the same.
4. The exponential temperature-compensated bandgap reference voltage source of claim 2, wherein:
the exponent compensating circuit includes: a fifth MOS tube, a sixth MOS tube, a seventh MOS tube and a third triode; the index compensation circuit is connected with the grids of the first MOS tube and the second MOS tube through the grid of the fifth MOS tube;
a source electrode of the fifth MOS tube and a collector electrode of the third triode are both connected with a reference voltage VDD, a drain electrode of the fifth MOS tube is connected with a drain electrode of the sixth MOS tube, a grid electrode and a drain electrode of the sixth MOS tube are in short circuit, the sixth MOS tube and the seventh MOS tube form a current mirror form, a drain electrode of the seventh MOS tube is connected with an emitter electrode of the third triode, and a base electrode of the third triode is connected with an input end of a summing output circuit; the source electrodes of the sixth MOS tube and the seventh MOS tube are grounded;
after the first current flows into the exponential compensation circuit, a third current proportional to the first current flows through an emitter of the third triode, and the third current generates a fourth current at a base of the third triode.
5. The exponential temperature-compensated bandgap reference voltage source of claim 2, wherein:
the start-up circuit includes: an eighth MOS tube, a ninth MOS tube and a capacitor; the source electrodes of the eighth MOS tube and the ninth MOS tube are both connected with a reference voltage VDD, the grid electrode and the drain electrode of the eighth MOS tube are in short circuit, the grid electrode of the ninth MOS tube is connected with the drain electrode of the eighth MOS tube, and the drain electrode of the ninth MOS tube is connected with the drain electrode of the first MOS tube and the drain electrode of the third MOS tube; one end of the capacitor is connected with the drain electrode of the first MOS tube, and the other end of the capacitor is grounded.
6. The exponential temperature-compensated bandgap reference voltage source of claim 4, wherein:
the summing output circuit includes: a tenth MOS tube, a fourth triode, a second resistor and a third resistor; one end of the second resistor and one end of the third resistor are both connected with the base electrode of the third triode;
a source electrode of the tenth MOS tube is connected with a reference voltage VDD, a grid electrode of the tenth MOS tube is connected with a grid electrode of the first MOS tube, a drain electrode of the tenth MOS tube is connected with the other end of the third resistor, the other end of the second resistor is connected with an emitting electrode of the fourth triode, and a base electrode and a collector electrode of the fourth triode are grounded; the drain electrode of the tenth MOS tube outputs reference voltage;
a second current flows through the third resistor.
7. A compensation method using the exponential temperature compensated bandgap reference voltage source of any one of claims 1 to 6,
the compensation method comprises the following steps:
step 1, starting a capacitor in a circuit to charge at the moment when the circuit is accessed to a reference voltage; the starting circuit enables the PTAT generating circuit to be conducted and started;
in the PTAT generating circuit, the current flowing through the collector electrode of the first triode is equal to the current flowing through the collector electrode of the second triode, and under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, a voltage difference value between the base electrode-emitter voltage of the first triode and the base electrode-emitter voltage of the second triode generates a first current on the first resistor;
step 3, extracting a high-order term from the nonlinear term of the base electrode-emitter voltage of the third triode;
calculating to obtain a second current according to the high-order term and a first proportional coefficient of the first current, wherein the first proportional coefficient is a shunt proportional coefficient of the first current passing through the second MOS tube and the tenth MOS tube;
calculating to obtain a third current according to the high-order term and a second proportional coefficient of the first current, wherein the second proportional coefficient is a shunt proportional coefficient of the first current passing through a second MOS tube, a fifth MOS tube, a sixth MOS tube and a seventh MOS tube;
step 4, calculating a fourth current generated by the third current at the base electrode of the third triode based on the relation between the current amplification factor of the third triode and the temperature;
and 5, calculating to obtain reference voltage by using the base-emitter voltage, the second resistor, the third resistor, the second current and the fourth current of the fourth triode according to the following relational expression:
V REF ＝V BE4 +I 2 R 3 +(I 2 -I 4 )R 2
in the formula (I), the compound is shown in the specification,
V REF is a reference voltage to be used as a reference voltage,
V BE4 is the base-emitter voltage of the fourth transistor,
I 2 is a second current of the electric current, and is,
I 4 is the fourth current, and is the fourth current,
R 2 is the resistance value of the second resistor, and is,
R 3 is a third resistance value;
step 6, fourth current I 4 To be provided with
For compensating the term by adjusting a first proportionality coefficient K 1 A second proportionality coefficient K 2 The resistance value of the first resistor, the resistance value of the second resistor and the resistance value of the third resistor enable the temperature drift of the output reference voltage to be zero; wherein, delta E G K is the boltzmann constant, and T is the temperature, which is the silicon bandgap reduction factor.
8. The method of claim 7,
the step 1 comprises the following steps:
step 1.1, when the circuit is connected to a reference voltage, the eighth MOS tube is connected into a diode connection mode, and the capacitor starts to charge;
step 1.2, the ninth MOS tube is conducted to form a current path from the reference voltage VDD to the ground through the ninth MOS tube, the third MOS tube and the first triode, and the PTAT generating circuit is conducted;
1.3, other circuit elements in the PTAT generating circuit are separated from a zero degeneracy state;
and 1.4, after the current in the PTAT generating circuit is stable, charging a capacitor in the starting circuit to a high level, so that the eighth MOS transistor and the ninth MOS transistor are both turned off, and the starting of the PTAT generating circuit is finished.
9. The method of claim 7,
in step 2, the base-emitter voltage V of the first triode BE1 Satisfies the following relation:
base-emitter voltage V of the second triode BE2 Satisfies the following relation:
in the formula (I), the compound is shown in the specification,
V T is thermal voltage, is 26mV at normal temperature,
I C1 in order to flow the collector current of the first transistor,
I C2 for a collector current to flow through the second transistor,
I S1 for reverse saturation current flowing through the emitter junction of the first transistor,
I S2 is a reverse saturation current flowing through the emitter junction of the first triode;
under the clamping action of the source electrode potentials of the third MOS tube and the fourth MOS tube, I C1 ＝I C2 。
10. The method of compensating an exponential temperature-compensated bandgap reference voltage source of claim 9,
the current I flowing through the first resistor 1 Satisfies the following relation:
in the formula (I), the compound is shown in the specification,
R 1 is the resistance value of the first resistor, and is,
and N is the ratio of the emitter junction areas of the second triode and the first triode.
11. The method of compensating an exponential temperature-compensated bandgap reference voltage source of claim 9,
in step 3, the nonlinear term of the base-emitter voltage of the slave triode satisfies the following relational expression:
in the formula (I), the compound is shown in the specification,
V REF (T) is a band gap reference voltage at a temperature T,
V G is a reference temperature T r The band-gap voltage of the lower silicon,
t is the temperature of the molten metal,
T r for the purpose of the reference temperature, the temperature,
V BE (T r ) To be at a reference temperature T r The lower base-emitter voltage is set to be,
eta is an exponential coefficient of electron mobility in silicon with temperature,
q is an electron charge amount;
when reference temperature T r Being constant, the non-linear term Tln (T) is the higher order term to be compensated.
12. The method of compensating an exponential temperature-compensated bandgap reference voltage source of claim 11,
calculating to obtain a second current I according to the high-order term and the first proportional coefficient of the first current 2 And satisfies the following relation:
in the formula (I), the compound is shown in the specification,
K 1 is a first scale factor and is a ratio of,
k is the boltzmann constant.
13. The method of compensating an exponential temperature-compensated bandgap reference voltage source of claim 11,
calculating to obtain a third current I according to the high-order term and a second proportionality coefficient of the first current 3 The following relational expression is satisfied:
in the formula (I), the compound is shown in the specification,
K 2 is a second scaling factor that is a function of,
k is the boltzmann constant.
14. The method of claim 13,
in step 4, the third current generates a fourth current I at the base of the third triode 4 The following relational expression is satisfied:
in the formula, β (T) is a relationship between the current amplification factor of the third transistor and the temperature.
15. The method of compensating an exponential temperature-compensated bandgap reference voltage source of claim 14,
β (T) satisfies the following relation:
in the formula (I), the compound is shown in the specification,
β ∞ is a constant fitted to beta (T) with temperature change,
ΔE G is the silicon bandgap reduction factor.
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| CN117093049A (en) * | 2023-10-19 | 2023-11-21 | 上海芯龙半导体技术股份有限公司 | Reference voltage source circuit and parameter adjusting method |
| CN117270621A (en) * | 2023-11-23 | 2023-12-22 | 上海芯炽科技集团有限公司 | Single temperature calibration structure of low temperature drift band gap reference circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117093049A (en) * | 2023-10-19 | 2023-11-21 | 上海芯龙半导体技术股份有限公司 | Reference voltage source circuit and parameter adjusting method |
| CN117093049B (en) * | 2023-10-19 | 2023-12-22 | 上海芯龙半导体技术股份有限公司 | Reference voltage source circuit and parameter adjusting method |
| CN117270621A (en) * | 2023-11-23 | 2023-12-22 | 上海芯炽科技集团有限公司 | Single temperature calibration structure of low temperature drift band gap reference circuit |
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