CN102968153A - Breaking point compensation and thermal limitation circuit - Google Patents

Breaking point compensation and thermal limitation circuit Download PDF

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Publication number
CN102968153A
CN102968153A CN2012104995734A CN201210499573A CN102968153A CN 102968153 A CN102968153 A CN 102968153A CN 2012104995734 A CN2012104995734 A CN 2012104995734A CN 201210499573 A CN201210499573 A CN 201210499573A CN 102968153 A CN102968153 A CN 102968153A
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voltage
temperature
transistor
breakpoint
circuit
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包兴坤
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SUZHOU GUIZHIYUAN MICROELECTRONIC CO Ltd
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SUZHOU GUIZHIYUAN MICROELECTRONIC CO Ltd
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Abstract

The invention discloses a breaking point compensation and thermal limitation circuit. The breaking point compensation and thermal limitation circuit comprises a bandgap voltage reference circuit which is provided with breaking point compensation to adjust the temperature coefficient of a reference voltage provided by a circuit. A voltage circuit also comprises a thermal limitation transistor and a bias is provided by a voltage with a positive temperature coefficient. When the temperature reaches a preset value, the thermal limitation transistor absorbs a quickly increased current.

Description

A kind of breakpoint compensation and thermal limit circuit
Technical field
The present invention relates to a kind of output voltage that is used for reducing bandgap voltage reference circuit vary with temperature and change the circuit of amplitude.
Background technology
The operating parameter of monolithic integrated optical circuit shows temperature dependency usually.In so temperature dependent source, a transistorized base-emitter voltage drop (V arranged BE), have and be generally-negative temperature coefficient of 2mV/ ℃, and by thermal voltage (V T) two unmatched transistorized base-emitter voltage drop (Δ V BE) difference show a positive temperature coefficient (PTC) that is directly proportional with temperature.
Summary of the invention
So the purpose of this invention is to provide a voltage reference circuit, it comprises a band-gap reference circuit and the temperature coefficient of the reference voltage that is provided by the band-gap reference circuit as temperature funtion is provided.
The further purpose of the present invention provides a reference voltage circuit, and it comprises that one also can provide the band-gap reference circuit that is biased to a hot breaking circuit.
These and other parts of the present invention are finished by a voltage reference circuit, in circuit, a breakpoint bucking voltage produces above in the situation of predetermined temperature in temperature, provides this predetermined temperature by a breakpoint compensation transistor that is biased to the positive temperature coefficient (PTC) that is produced by bandgap reference voltage.
Technical solution of the present invention
In the design of Analogous Integrated Electronic Circuits voltage regulator etc., be necessary to set up a voltage or current reference at inside circuit, it is in fact not temperature variant.Bandgap voltage reference circuit is used to provide a reference voltage or electric current often.Such circuit produces a metastable output voltage to have positive temperature coefficient (PTC) (voltage difference is Δ V by compensating one BE) base-emitter voltage drop V BEThe equipment of negative temperature coefficient.Especially, the two temperature coefficient produces in circuit, and voltage difference delta V BEPositive temperature coefficient (PTC) since the thermal voltage scaling factor and temperature (K) have nothing to do, with base-emitter voltage drop V BENegative temperature coefficient to combine to obtain a nominal temperature dependency be zero output voltage.
Yet in practice, the output voltage of bandgap voltage reference circuit has kept temperature dependency to a certain degree, because the temperature coefficient of opposite polarity all is nonlinear, like this, drift rate separately changes with temperature.Therefore, along with the variation of temperature, these two coefficients produce a nonlinear network temperature coefficient to not remaining on a fixing proportionate relationship.In addition, the device that forms this circuit shows other not nonlinear temperature coefficients of separate compensation usually.The summation of non-compensation temperature coefficient produces one and varies with temperature and the output voltage network of nonlinearities change.
For example, be called in the type of band-gap reference circuit of Brokaw Cell bandgap voltage reference circuit a kind of, output voltage shows temperature dependency reduces output voltage gradually under lower and higher temperature, when having arrived the drafting temperature, make the approximate para-curve of output voltage curve shape.The degeneration of this output voltage under lower and higher temperature has limited the minimum temperature coefficient, along with temperature range increases it can be obtained.
Many circuit of band-gap reference that utilize also need overtemperature prote.This protection is necessary, to prevent keeping permanent damage owing to high power consumption causes excess temperature to rise to cause high power circuit such as voltage regulator etc.When temperature surpassed predetermined threshold levels, hot breaking circuit provided necessary protection by temperature and the automatic shutdown circuitry of testing circuit.Because regulator can be worked during near required shutoff temperature in temperature, so must not affecting circuit, thermal overload protection works during near shutoff temperature in temperature.Simple hot breaking circuit has lower thermal enhancement usually.Therefore, regulator uses these simple shutdown circuits that shutoff temperature must be set to be higher than desirable temperature.
In view of the foregoing, hope can provide a reference voltage circuit to comprise a band-gap reference circuit, produces to have the temperature dependent output voltage less than bandgap reference circuit.
It also needs to provide a reference voltage circuit, comprises a band-gap reference circuit, when operating temperature surpasses predetermined threshold, and the circuit around it also can be closed rapidly.
In addition, can improve the temperature independence of the reference voltage that is provided by a band-gap reference circuit, and provide hot turn-off capacity in the situation that does not greatly increase circuit complexity, this will be desirable.
Documents, patent of invention: voltage generating circuit, application number: 200520009466.9.
Description of drawings
Fig. 1 is the synoptic diagram of a conventional Brokaw cell band-gap reference circuit;
Fig. 2 is a figure, has shown the output voltage of Brokaw cell bandgap circuit in operating temperature range of Fig. 1;
Fig. 3 is a figure, has shown that reference voltage circuit comprises the output voltage of Brokaw cell circuit and breakpoint compensation system;
Fig. 4 is a schematic diagram that embodies the voltage reference circuit that the present invention includes the breakpoint temperature compensation;
Fig. 5 is a figure, has shown the operation of the thermally cutoff device of breakpoint compensation and Fig. 4.
Embodiment
With reference to figure 1, it has shown traditional Brokaw cell band-gap reference circuit 100.Circuit 100 comprises product body pipe 102, and its collector connects a load 104, and its base stage is connected to the base stage of transistor 106.Transistor 102 has a plurality of transmitters to be held together, and is used to provide an emitter area, is n times of transistor 106 base stages, so that transistor 102 and 106 is operated in different current densities.Although other n values also can be used, the value of n normally 10.One end of the emitter contact resistance 110 of transistor 102, and the other end of resistance 110 connects the emitter of transistor 106 and an end of resistance 112.The other end ground connection of resistance 112.The collector of transistor 106 is connected to load 108.Amplifier 114 is connected to a lead-out terminal V o, a non-inverting input is connected to the collector of transistor 106, and the collector of an inverting input connection transistor 102.
Load 104 and 108 can be used as a mirror current source, and the collector in transistor 102 and 106 provides the basic electric current I that equates respectively 1' and I 2'.They also may be simple ohmic loads.Under any circumstance, collector current does not need to equate.(collector current) can resize ratio, becomes the effects equivalent of certain ratio to reach emitter area.Suppose to provide base current I 3Be provided for transistor 104 and 106 and come their base stage-emitter junctions separately of forward bias, transmitter transistor 102 and the difference of the emitter area between 106 the emitter cause voltage Δ V on the resistance 110 BEDifference.Ignore the impact of base current, electric current I 1Equal electric current I 1', and electric current I 2Equal electric current I 2'.Current value equal the to flow through electric current I of resistance 112 1And I 2Summation.
Transistor 102 and 106 base voltage V oEqual the base-emitter voltage V of transistor 106 BEWith resistance 112 both end voltage sums.The base-emitter voltage V of transistor 106 BEHave one to be about-negative temperature coefficient of 2mV/ ℃.Voltage difference delta V BEHas a positive temperature coefficient (PTC), because it is a thermal voltage V TFunction, be directly proportional with absolute temperature successively, according to formula V T=KT/q, the k here is Boltzmann constant, q is electron charge, and T is absolute temperature.To such an extent as to negative temperature coefficient and the voltage difference delta V of the base-emitter knot of this circuit operation transistor 106 BEPositive temperature coefficient (PTC) opposite.Approximate to first, the base voltage V when transistor 102 and 106 oWhen being about 1.2 (band gap voltage silicon), this coefficient is cancelled out each other, like this along with temperature variation, and voltage V oNominally the variation on that voltage levvl is zero.When emissivity n and resistance R 1Also have 112 value that the voltage V that provides to approximate 1.2V is provided oThe time, thereby this circuit produces a temperature stabilization voltage V o
This principle has been emphasized the basic theories running of circuit 100, and it is with the base-emitter voltage V of transistor 106 BETemperature dependency and voltage difference delta V BEAs linear term.Yet each is the nonlinearities change along with temperature variation in fact.As a result, circuit 100 has showed that a value under the temperature of once only having is zero clean temperature coefficient and varies with temperature the voltage V that changes o
As can be seen from Figure 2, output voltage V oCurve 200 reach at a temperature V PUnder crest voltage V P, and along with temperature from the value V PIncrease or reduce to reduce and reduce, curve 200 slopes are zero, show that this circuit is temperature stabilization at that aspect, but stable with a growth rate along with temperature from temperature T PRaise or reduce and lose.
The measurement of the temperature on average stability of a Brokaw Cell circuit output voltage centers on curve 200 at specified temp T by drawing a rectangle 202 1_ T 2Set up in the scope, rectangle 202 enough is used for greatly comprising the integral body of curve 200.The area of rectangle 202 is less, and the output voltage that surpasses given temperature range of circuit is more stable.
One is reduced the unsettled approach of voltage reference circuit is for the breakpoint compensation is provided.Breakpoint compensates by realizing in correct influences to the circuit running of the lower introducing of a certain specified temp (breakpoint temperature), is used for changing the clean temperature coefficient of circuit, thereby and changes the shape of curve 200 with the area of minimizing rectangle 202.
Fig. 3 has shown how the breakpoint compensation affects the output voltage of a typical Brokaw Cell circuit.Curve 300 has represented a kind of in temperature T 1_ T 2The output voltage of the theoretical Brokaw Cell circuit in the scope.This temperature range is that such curve of output 300 has a temperature T PUnder summit V PCentre in temperature range.The area representative of square type 302 is at temperature range T 1_ T 2Interior instable degree.Assumed curve 300 is rigidity, and can " block " rather than " bending ", and that curve 300 is rotatable about some T 1, shown in figure arrow 304, the area of rectangle 302 can reduce in theory, is four factors: rotating curve 300 down to shown in the position of curve 306; Curve 306 is at a T PThe place is blocked; And curve 306 is at T PAnd T 2Between rotating part upwards to shown in the position of curve 308.The area of rectangle 310 represents the medial temperature instability of curve 308.
The impact of this manipulation is in order to give one in Brokaw Cell circuit at temperature range T 1_ T PInterior more negative temperature coefficient, and make this temperature coefficient at temperature range T P_ T 2Interior corrigendum.Therefore the breakpoint compensation is that the function that changes the circuit temperature coefficient into temperature is a kind of means.
The invention provides a kind of circuit of simple novelty, compensate to improve the temperature stability of a bandgap voltage reference circuit by breakpoint, such as Brokaw Cell circuit.Although the present invention discusses under the background of Brokaw Cell circuit, we will understand that other band-gap reference circuits can be utilized and the present invention does not limit and only uses Brokaw Cell circuit.For example, the present invention can use the voltage difference with positive temperature coefficient (PTC) that produces between the emitter of band-gap reference two transistor in the base stage of two transistor rather than Brokaw Cell circuit.Like this, other band-gap reference circuits are well-known, do not further specify except not having.
Referring now to Fig. 4, the specific demonstration of reference voltage circuit is used for an integrated circuit voltage regulator among the present invention.Brokaw Cell circuit 100 comprises transistor 102 and 106, resistance 110 and 112, and they connect in mode same as shown in Figure 1.The selected value of emissivity n is 10, so large 10 times of the emitter area of the total emission utmost point Area Ratio transistor 106 of transistor 102 is although n also can get other values.This is desirable, and n should be large as much as possible, is determined by use integrated circuit of the present invention to the sizing restriction, with the impact of noise reduction on circuit operation.
Resistance 110 and 112 resistance determine that Brokaw Cell circuit 100 is lower than temperature coefficient under the breakpoint temperature in temperature, and the base stage that preferably is chosen in transistor 102 and 106 produces a reference voltage V o, it has temperature T among temperature characteristics such as Fig. 3 1With T PBetween 306 parts.When this condition satisfies, reference voltage V oThe value that an about 1.2V is preferably arranged.For this reason, the resistance of resistance 110 is chosen, like this electric current I 1Produce the voltage drop of an about 60mV by resistance 110, and the resistance of resistance 112 is chosen, like this in the lower electric current I of room temperature (25 ℃) 1And I 2Summation produce the voltage drop of a 600mV by resistance 112.In Fig. 4, a given value is 10 emissivity, and resistance 110 and 112 has respectively the resistance of 1.0 kilo-ohms and 5.0 kilo-ohms.
Breakpoint compensating circuit 400 comprises resistance 402, transistor 404 and resistance 406. Transistor 102 and 106 base stage are connected to an end of resistance 402 and the collector of transistor 404.The other end of resistance 402 is connected to the emitter of transistor 408, and 408 collector is connected to the collector that supply voltage and base stage are connected to transistor 106 and 412.The base stage of transistor 404 is connected to resistance R 1And R 2Between, and the emitter of transistor 404 is connected to an end of resistance 406.The other end ground connection of resistance 406.
In operating process, current ratio determines by the transistor 410 in the Brokaw Cell circuit 100 and 412, the voltage source V that is connected to as the mirror current source of a routine sAnd between the collector of transistor 102 and 106.In electric current I 1' and I 2' descend the transistor 410 and 412 of work to have basic equal value.Ignore the impact of base current, electric current I 1' and I 2' equal in fact electric current I 1And I 2The base-emitter voltage of transistor 106 is about 600mV, and like this, transistor 102 and 106 base voltage are about 1.2V.Because the voltage difference delta V between the transistor 102 and 106 BEPositive temperature coefficient (PTC), the voltage of resistance 110 and 112 intersections raises with about 1.2mV/ ℃ speed.Simultaneously, the base-emitter voltage V of transistor 106 BEHave and be about-negative temperature coefficient of 1.2mV/ ℃; Yet, this two coefficient variation with temperature and change this reference voltage V on the base stage of sample transistor 102 and 106 oVariation with temperature and changing.For example, be that voltage will change with the variation of temperature on the temperature curve 306 shown in Figure 3 in-55 ℃ to+150 ℃ the situation in temperature range.Can find out as shown in Figure 3 reference voltage V oHaving a temperature coefficient (being shown by the slope of curve 306) raises with temperature and reduces and this is that the temperature range major part is to bear.
For the negative temperature coefficient of compensated curve 306, when the base voltage of transistor 404 increased along with the temperature rising, wherein resistance 402 and 406 was used for increasing temperature coefficient, reaches a level and responds the predetermined breakpoint temperature T P, be preferably 25 ℃.Because temperature is lower than breakpoint temperature, by the electric current I of resistance 402 3Close to zero, and output voltage V OUTBe substantially equal to the reference voltage V of transistor 102 and 106 base stages oWhen temperature rose to breakpoint temperature, the enough height of the base voltage of transistor 404 were opened transistor, and had a voltage drop to occur by resistance 402, like this output voltage V OUTBecome greater than the reference voltage V of transistor 102 and 106 base stages oElectric current I 3Variation with temperature shows in Fig. 5.Output voltage V OUTBase voltage than transistor 102 and 106 is determined by the temperature coefficient of the emitter voltage of transistor 404 and the ratio of resistance 402 and 406 with the speed that temperature increases.
Because temperature is lower than breakpoint temperature, the base voltage of transistor 404 is not enough to open transistor, and the emitter voltage that does not have like this current flowing resistance 406 and transistor 404 is zero.Because temperature meets or exceeds breakpoint temperature, the about 4mV/ of the temperature coefficient of the emitter voltage of transistor 404 ℃.This coefficient is that the base-emitter magnitude of voltage of 2mV/ ℃ voltage temperature coefficient and transistor 404 causes for-2mV/ ℃ temperature coefficient by the base stage value that acts on transistor 404.But a value of resistance is about 0.025.Give an example, set up one 25 ℃ breakpoint, and the breakpoint compensation with the positive temperature coefficient (PTC) that is about 0.1mV/ ℃ will be provided, resistance 402 values are about 200 ohm and resistance 406 values and are about 7.9 kilo-ohms, and this is desirable.
We can be understood as selected resistance is representative, and can the placement different breakpoint and the penalty coefficients except 0.1/ ℃ beyond 25 ℃.Breakpoint temperature value and penalty coefficient have been selected to produce voltage/temperature curve has the temperature stability of optimization in ℃ to+150 ℃ in temperature range-55.The present invention also comprises, does not almost increase complicacy, and one is adopted the hot breaking circuit of the temperature coefficient of breakpoint compensating circuit to be used to provide an accurate thermal load response.With reference to figure 4, hot breaking circuit 450 comprises transistor 452, and its base stage is connected to the emitter of transistor 404, and its grounded emitter and its collector are connected to the voltage regulator of driving circuit 454.As mentioned above, the emitter voltage of transistor 404 is about zero when temperature is lower than breakpoint temperature, and a positive temperature coefficient (PTC) that is about 4mV/ ℃ is arranged when breakpoint temperature.The emitter voltage of transistor 404 makes the base-emitter knot biasing of transistor 452.Therefore, the voltage that acts on transistor 452 base stages is started from scratch under 25 ℃ temperature to be increased with 4mV/ ℃ speed.The base-emitter voltage of transistor 452 has a value to be-2mV/ ℃ temperature coefficient, and this base-emitter voltage need to make transistor 452 with-2mV/ ℃ rate reduction like this.Because these coefficients, one 6mV/ ℃ available heat drive signal function in the base stage of transistor 452.Heat drives signal and causes transistor 452 to be opened under a temperature, and it preferably is selected as the maximum temperature value that slightly surpasses voltage regulator.In the circuit of Fig. 4, transistor 452 is preferably in one and is about under 150 ℃ the temperature and opens, with electric current I 4From driving circuit 454, pull out.To this, the conventional current testing circuit in the driving circuit 454 is as electric current I 4The power stage of a limit of functions voltage regulator of size.As can be seen from Figure 5, the electric current I of curve 504 representatives 4, when temperature rises to more than 150 ℃, increase sharply.This increases fast and allows hot breaking circuit only to be used for responding temperature conditions a little more than the maximum operation temperature of expection, thereby closes rapidly driving circuit 454, with any may the infringement that prevents that ongoing operation causes when temperature surpasses the ratings of regulator.Transistor 452 opens fast when temperature is increased to more than 150 ℃, be that value by the voltage that acts on transistor 452 base stages is that the value of the base-emitter voltage of 4mV/ ℃ temperature coefficient and transistor 452 causes for-2mV/ ℃ temperature coefficient, they produce together one 6mV/ ℃ available heat and drive signal to transistor 452.
Therefore a new reference voltage circuit comprises a bandgap voltage reference circuit, a breakpoint compensating circuit and a hot breaking circuit that provides.One aspect artistic skilled people will to understand the present invention also practicable except described imbody, this imbody is for for the purpose of illustrating rather than restriction, and the present invention only is subjected to above claim restriction with reference to figure 1, and it has shown traditional Brokaw cell band-gap reference circuit 100.Circuit 100 comprises transistor 102, and its collector connects a load 104, and its base stage is connected to the base stage of transistor 106.Transistor 102 has a plurality of transmitters to be held together, and is used to provide an emitter area, is n times of transistor 106 base stages, so that transistor 102 and 106 is operated in different current densities.Although other n values also can be used, the value of n normally 10.One end of the emitter contact resistance 110 of transistor 102, and the other end of resistance 110 connects the emitter of transistor 106 and an end of resistance 112.The other end ground connection of resistance 112.The collector of transistor 106 is connected to load 108.Amplifier 114 is connected to a lead-out terminal V o, a non-inverting input is connected to the collector of transistor 106, and the collector of an inverting input connection transistor 102.
Load 104 and 108 can be used as a mirror current source, and the collector in transistor 102 and 106 provides the basic electric current I that equates respectively 1' and I 2'.They also may be simple ohmic loads.Under any circumstance, collector current does not need to equate.(collector current) can resize ratio, becomes the effects equivalent of certain ratio to reach emitter area.Suppose to provide base current I 3Be provided for transistor 104 and 106 and come their base stage-emitter junctions separately of forward bias, transmitter transistor 102 and the difference of the emitter area between 106 the emitter cause voltage Δ V on the resistance 110 BEDifference.Ignore the impact of base current, electric current I 1Equal electric current I 1', and electric current I 2Equal electric current I 2'.Current value equal the to flow through electric current I of resistance 112 1And I 2Summation.
Transistor 102 and 106 base voltage V oEqual the base-emitter voltage V of transistor 106 BEWith resistance 112 both end voltage sums.The base-emitter voltage V of transistor 106 BEHave one to be about-negative temperature coefficient of 2mV/ ℃.Voltage difference delta V BEHas a positive temperature coefficient (PTC), because it is a thermal voltage V TFunction, be directly proportional with absolute temperature successively, according to formula V T=KT/q, the k here is Boltzmann constant, q is electron charge, and T is absolute temperature.To such an extent as to negative temperature coefficient and the voltage difference delta V of the base-emitter knot of this circuit operation transistor 106 BEPositive temperature coefficient (PTC) opposite.Approximate to first, the base voltage V when transistor 102 and 106 oWhen being about 1.2 (band gap voltage silicon), this coefficient is cancelled out each other, like this along with temperature variation, and voltage V oNominally the variation on that voltage levvl is zero.When emissivity n and resistance R 1Also have 112 value that the voltage V that provides to approximate 1.2V is provided oThe time, thereby this circuit produces a temperature stabilization voltage V o
This principle has been emphasized the basic theories running of circuit 100, and it is with the base-emitter voltage V of transistor 106 BETemperature dependency and voltage difference delta V BEAs linear term.Yet each is the nonlinearities change along with temperature variation in fact.As a result, circuit 100 has showed that a value under the temperature of once only having is zero clean temperature coefficient and varies with temperature the voltage V that changes o
As can be seen from Figure 2, output voltage V oCurve 200 reach at a temperature V PUnder crest voltage V P, and along with temperature from the value V PIncrease or reduce to reduce and reduce, curve 200 slopes are zero, show that this circuit is temperature stabilization at that aspect, but stable with a growth rate along with temperature from temperature T PRaise or reduce and lose.
The measurement of the temperature on average stability of a Brokaw Cell circuit output voltage centers on curve 200 at specified temp T by drawing a rectangle 202 1-T 2Set up in the scope, rectangle 202 enough is used for greatly comprising the integral body of curve 200.The area of rectangle 202 is less, and the output voltage that surpasses given temperature range of circuit is more stable.
One is reduced the unsettled approach of voltage reference circuit is for the breakpoint compensation is provided.Breakpoint compensates by realizing in correct influences to the circuit running of the lower introducing of a certain specified temp (breakpoint temperature), is used for changing the clean temperature coefficient of circuit, thereby and changes the shape of curve 200 with the area of minimizing rectangle 202.
Fig. 3 has shown how the breakpoint compensation affects the output voltage of a typical Brokaw Cell circuit.Curve 300 has represented a kind of in temperature T 1-T 2The output voltage of the theoretical Brokaw Cell circuit in the scope.This temperature range is that such curve of output 300 has a temperature T PUnder summit V PCentre in temperature range.The area representative of square type 302 is at temperature range T 1-T 2Interior instable degree.Assumed curve 300 is rigidity, and can " block " rather than " bending ", and that curve 300 is rotatable about some T 1, shown in figure arrow 304, the area of rectangle 302 can reduce in theory, is four factors: rotating curve 300 down to shown in the position of curve 306; Curve 306 is at a T PThe place is blocked; And curve 306 is at T PAnd T 2Between rotating part upwards to shown in the position of curve 308.The area of rectangle 310 represents the medial temperature instability of curve 308.
The impact of this manipulation is in order to give one in Brokaw Cell circuit at temperature range T 1-T PInterior more negative temperature coefficient, and make this temperature coefficient at temperature range T P-T 2Interior corrigendum.Therefore the breakpoint compensation is that the function that changes the circuit temperature coefficient into temperature is a kind of means.
The invention provides a kind of circuit of simple novelty, compensate to improve the temperature stability of a bandgap voltage reference circuit by breakpoint, such as Brokaw Cell circuit.Although the present invention discusses under the background of Brokaw Cell circuit, we will understand that other band-gap reference circuits can be utilized and the present invention does not limit and only uses Brokaw Cell circuit.For example, the present invention can use the voltage difference with positive temperature coefficient (PTC) that produces between the emitter of band-gap reference two transistor in the base stage of two transistor rather than Brokaw Cell circuit.Like this, other band-gap reference circuits are well-known, do not further specify except not having.
Referring now to Fig. 4, the specific demonstration of reference voltage circuit is used for an integrated circuit voltage regulator among the present invention.Brokaw Cell circuit 100 comprises transistor 102 and 106, resistance 110 and 112, and they connect in mode same as shown in Figure 1.The selected value of emissivity n is 10, so large 10 times of the emitter area of the total emission utmost point Area Ratio transistor 106 of transistor 102 is although n also can get other values.This is desirable, and n should be large as much as possible, is determined by use integrated circuit of the present invention to the sizing restriction, with the impact of noise reduction on circuit operation.
Resistance 110 and 112 resistance determine that Brokaw Cell circuit 100 is lower than temperature coefficient under the breakpoint temperature in temperature, and the base stage that preferably is chosen in transistor 102 and 106 produces a reference voltage V o, it has temperature T among temperature characteristics such as Fig. 3 1With T PBetween 306 parts.When this condition satisfies, reference voltage V oThe value that an about 1.2V is preferably arranged.For this reason, the resistance of resistance 110 is chosen, like this electric current I 1Produce the voltage drop of an about 60mV by resistance 110, and the resistance of resistance 112 is chosen, like this in the lower electric current I of room temperature (25 ℃) 1And I 2Summation produce the voltage drop of a 600mV by resistance 112.In Fig. 4, a given value is 10 emissivity, and resistance 110 and 112 has respectively the resistance of 1.0 kilo-ohms and 5.0 kilo-ohms.
Breakpoint compensating circuit 400 comprises resistance 402, transistor 404 and resistance 406. Transistor 102 and 106 base stage are connected to an end of resistance 402 and the collector of transistor 404.The other end of resistance 402 is connected to the emitter of transistor 408, and 408 collector is connected to the collector that supply voltage and base stage are connected to transistor 106 and 412.The base stage of transistor 404 is connected to resistance R 1And R 2Between, and the emitter of transistor 404 is connected to an end of resistance 406.The other end ground connection of resistance 406.
In operating process, current ratio determines by the transistor 410 in the Brokaw Cell circuit 100 and 412, the voltage source V that is connected to as the mirror current source of a routine sAnd between the collector of transistor 102 and 106.In electric current I 1' and I 2' descend the transistor 410 and 412 of work to have basic equal value.Ignore the impact of base current, electric current I 1' and I 2' equal in fact electric current I 1And I 2The base-emitter voltage of transistor 106 is about 600mV, and like this, transistor 102 and 106 base voltage are about 1.2V.Because the voltage difference delta V between the transistor 102 and 106 BEPositive temperature coefficient (PTC), the voltage of resistance 110 and 112 intersections raises with about 1.2mV/ ℃ speed.Simultaneously, the base-emitter voltage V of transistor 106 BEHave and be about-negative temperature coefficient of 1.2mV/ ℃; Yet, this two coefficient variation with temperature and change this reference voltage V on the base stage of sample transistor 102 and 106 oVariation with temperature and changing.For example, be that voltage will change with the variation of temperature on the temperature curve 306 shown in Figure 3 in-55 ℃ to+150 ℃ the situation in temperature range.Can find out as shown in Figure 3 reference voltage V oHaving a temperature coefficient (being shown by the slope of curve 306) raises with temperature and reduces and this is that the temperature range major part is to bear.
For the negative temperature coefficient of compensated curve 306, when the base voltage of transistor 404 increased along with the temperature rising, wherein resistance 402 and 406 was used for increasing temperature coefficient, reaches a level and responds the predetermined breakpoint temperature T P, be preferably 25 ℃.Because temperature is lower than breakpoint temperature, by the electric current I of resistance 402 3Close to zero, and output voltage V OUTBe substantially equal to the reference voltage V of transistor 102 and 106 base stages oWhen temperature rose to breakpoint temperature, the enough height of the base voltage of transistor 404 were opened transistor, and had a voltage drop to occur by resistance 402, like this output voltage V OUTBecome greater than the reference voltage V of transistor 102 and 106 base stages oElectric current I 3Variation with temperature shows in Fig. 5.Output voltage V OUTBase voltage than transistor 102 and 106 is determined by the temperature coefficient of the emitter voltage of transistor 404 and the ratio of resistance 402 and 406 with the speed that temperature increases.
Because temperature is lower than breakpoint temperature, the base voltage of transistor 404 is not enough to open transistor, and the emitter voltage that does not have like this current flowing resistance 406 and transistor 404 is zero.Because temperature meets or exceeds breakpoint temperature, the about 4mV/ of the temperature coefficient of the emitter voltage of transistor 404 ℃.This coefficient is that the base-emitter magnitude of voltage of 2mV/ ℃ voltage temperature coefficient and transistor 404 causes for-2mV/ ℃ temperature coefficient by the base stage value that acts on transistor 404.But a value of resistance is about 0.025.Give an example, set up one 25 ℃ breakpoint, and the breakpoint compensation with the positive temperature coefficient (PTC) that is about 0.1mV/ ℃ will be provided, resistance 402 values are about 200 ohm and resistance 406 values and are about 7.9 kilo-ohms, and this is desirable.
We can be understood as selected resistance is representative, and can the placement different breakpoint and the penalty coefficients except 0.1/ ℃ beyond 25 ℃.Breakpoint temperature value and penalty coefficient have been selected to produce voltage/temperature curve has the temperature stability of optimization in ℃ to+150 ℃ in temperature range-55.The present invention also comprises, does not almost increase complicacy, and one is adopted the hot breaking circuit of the temperature coefficient of breakpoint compensating circuit to be used to provide an accurate thermal load response.With reference to figure 4, hot breaking circuit 450 comprises transistor 452, and its base stage is connected to the emitter of transistor 404, and its grounded emitter and its collector are connected to the voltage regulator of driving circuit 454.As mentioned above, the emitter voltage of transistor 404 is about zero when temperature is lower than breakpoint temperature, and a positive temperature coefficient (PTC) that is about 4mV/ ℃ is arranged when breakpoint temperature.The emitter voltage of transistor 404 makes the base-emitter knot biasing of transistor 452.Therefore, the voltage that acts on transistor 452 base stages is started from scratch under 25 ℃ temperature to be increased with 4mV/ ℃ speed.The base-emitter voltage of transistor 452 has a value to be-2mV/ ℃ temperature coefficient, and this base-emitter voltage need to make transistor 452 with-2mV/ ℃ rate reduction like this.Because these coefficients, one 6mV/ ℃ available heat drive signal function in the base stage of transistor 452.Heat drives signal and causes transistor 452 to be opened under a temperature, and it preferably is selected as the maximum temperature value that slightly surpasses voltage regulator.In the circuit of Fig. 4, transistor 452 is preferably in one and is about under 150 ℃ the temperature and opens, with electric current I 4From driving circuit 454, pull out.To this, the conventional current testing circuit in the driving circuit 454 is as electric current I 4The power stage of a limit of functions voltage regulator of size.As can be seen from Figure 5, the electric current I of curve 504 representatives 4, when temperature rises to more than 150 ℃, increase sharply.This increases fast and allows hot breaking circuit only to be used for responding temperature conditions a little more than the maximum operation temperature of expection, thereby closes rapidly driving circuit 454, with any may the infringement that prevents that ongoing operation causes when temperature surpasses the ratings of regulator.Transistor 452 opens fast when temperature is increased to more than 150 ℃, be that value by the voltage that acts on transistor 452 base stages is that the value of the base-emitter voltage of 4mV/ ℃ temperature coefficient and transistor 452 causes for-2mV/ ℃ temperature coefficient, they produce together one 6mV/ ℃ available heat and drive signal to transistor 452.
Therefore, a new reference voltage circuit comprises a bandgap voltage reference circuit, a breakpoint compensating circuit and a hot breaking circuit that provides.
Although the present invention is described by a concrete example, this example is just in order to illustrate the present invention, and should not limit the present invention.As long as no breaking away from essence of the present invention and meeting definition in the claim, make suitable modification at above-mentioned example and still belong to category of the present invention.

Claims (10)

1. a breakpoint compensates and the thermal limit circuit, it is characterized in that: under a working temperature that has in operating temperature range, provide in the reference voltage circuit of output terminal of output voltage, first and second liang of positive sources provide reference voltage according to different temperatures coefficient at first node with a bandgap reference voltage, at the voltage that Section Point provides the difference between the base-emitter voltage with two transistor to be directly proportional and to have positive temperature coefficient (PTC), a breakpoint compensating circuit comprises: be connected to the first resistance device between output terminal and the first node; The device that is connected to lead-out terminal and the first supply terminal is used to provide an electric current to output terminal; It is anodal to be connected in addition first node, Section Point and second source, and the compensation system of response Section Point voltage, when operating temperature arrives a breakpoint compensation threshold value, be used for producing a bucking voltage by described the first resistance device, be that output voltage is reference voltage and bucking voltage sum, and surpass the reference voltage that is equal to or higher than the breakpoint temperature threshold value under the operating temperature.Described the first resistance device comprises a resistance.The anodal temperature coefficient of Section Point voltage is equal to or greater than 2mV/ ℃.
2. breakpoint according to claim 1 compensates and the thermal limit circuit, it is characterized in that: described compensation system comprises a first transistor and second resistance device, the base stage of wherein said the first transistor is connected to Section Point, the collector of described the first transistor is connected to described the first resistance device, and described the second resistance device is connected between the emitter and second source positive pole of described the first transistor; Described the first and second resistance devices comprise a lot of resistance.
3. breakpoint according to claim 1 compensates and the thermal limit circuit, it is characterized in that: described compensation system produces the voltage with the anodal temperature coefficient that is higher than Section Point at the 3rd node, this circuit also comprises: be connected to the 3rd utmost point node and respond the thermally cutoff device of the 3rd utmost point node voltage, when operating voltage surpassed the heat shutoff temperature threshold, it was used to provide a heat shutoff signal.
4. breakpoint according to claim 3 compensates and the thermal limit circuit, it is characterized in that: described heat shutoff device comprises a transistor seconds, it has a voltage bias at the base-emitter knot of the 3rd node, and the heat shutoff signal appears at the collector of described transistor seconds.
5. breakpoint according to claim 4 compensates and the thermal limit circuit, it is characterized in that: the voltage that is biased in described transistor seconds base-emitter knot has a positive temperature coefficient (PTC) that effectively is equal to or greater than 6mV/ ℃.
6. breakpoint according to claim 1 compensates and the thermal limit circuit, it is characterized in that: in a reference voltage circuit with output terminal, this output terminal is used to provide an output voltage under the working temperature in operating temperature range, the first and second positive sources provide one according to temperature coefficient and different reference voltages with a bandgap reference voltage at first node, and Section Point provide one with two transistor base-emitter voltages between difference be directly proportional and a reference voltage with positive temperature coefficient (PTC) arranged, a breakpoint compensating circuit comprises: a first transistor that is connected between output terminal and the first node.
7. breakpoint compensation according to claim 1 and thermal limit circuit is characterized in that: be connected to the device of the first positive source and be used to provide an electric current to the output terminal of output terminal; A transistor; Also has second resistance that is connected to the anodal end of second source; Wherein: described transistorized base stage is connected to Section Point, collector be connected to that first node and emitter be connected to described transistor seconds another bring in the 3rd node of definition, when running temperature arrives a breakpoint temperature threshold value, described transistorized running provides the breakpoint temperature compensation by producing compensated voltage drop by described the first resistance, like this, output voltage is reference voltage and bucking voltage sum, and surpasses the reference voltage that is equal to or higher than the breakpoint temperature threshold value under the operating temperature.
8. breakpoint according to claim 6 compensates and the thermal limit circuit, it is characterized in that: a transistor seconds that is used to provide hot cut-off signals, described transistor seconds has a base-emitter circuit, it is setovered by the 3rd node voltage, this voltage has an effective positive temperature coefficient (PTC), is equal to or greater than 6mV/ ℃.
9. breakpoint according to claim 1 compensates and the thermal limit circuit, it is characterized in that: in a circuit, has the output terminal that is used to provide an output voltage temperature in operating temperature range, a bandgap reference voltage provides first voltage with temperature coefficient at first node, and providing the second voltage of the positive temperature coefficient (PTC) that is directly proportional with the base-emitter voltage difference of two transistor and has at Section Point, a breakpoint compensating circuit comprises: be used to provide an electric current to the device of output terminal; Connect in addition output terminal and first node, and the device at Section Point response second voltage, when operating voltage reaches a breakpoint compensation threshold value, it is used for producing a bucking voltage, be output voltage by at least the first and the bucking voltage sum, surpass at lower the first voltage composition of operating temperature (surpassing the breakpoint threshold temperature).Bucking voltage rises with operating voltage.
10. breakpoint according to claim 8 compensates and the thermal limit circuit, and it is characterized in that: described bucking voltage generation device comprises: a resistance device that is connected between output terminal and the first node; With is connected a transistor that connects first node and connect Section Point, namely when operating voltage surpassed the breakpoint threshold voltage, described transistor caused the bucking voltage of that generation to pass through described crystal unit.
CN2012104995734A 2012-11-29 2012-11-29 Breaking point compensation and thermal limitation circuit Pending CN102968153A (en)

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Citations (5)

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US4249122A (en) * 1978-07-27 1981-02-03 National Semiconductor Corporation Temperature compensated bandgap IC voltage references
US4447784A (en) * 1978-03-21 1984-05-08 National Semiconductor Corporation Temperature compensated bandgap voltage reference circuit
US4789819A (en) * 1986-11-18 1988-12-06 Linear Technology Corporation Breakpoint compensation and thermal limit circuit
CN1758176A (en) * 2005-02-11 2006-04-12 钰创科技股份有限公司 Temp stabilized reference voltage circuit
US20080180070A1 (en) * 2006-10-24 2008-07-31 Matsushita Electric Industrial Co., Ltd. Reference voltage generation circuit

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4447784A (en) * 1978-03-21 1984-05-08 National Semiconductor Corporation Temperature compensated bandgap voltage reference circuit
US4447784B1 (en) * 1978-03-21 2000-10-17 Nat Semiconductor Corp Temperature compensated bandgap voltage reference circuit
US4249122A (en) * 1978-07-27 1981-02-03 National Semiconductor Corporation Temperature compensated bandgap IC voltage references
US4789819A (en) * 1986-11-18 1988-12-06 Linear Technology Corporation Breakpoint compensation and thermal limit circuit
CN1758176A (en) * 2005-02-11 2006-04-12 钰创科技股份有限公司 Temp stabilized reference voltage circuit
US20080180070A1 (en) * 2006-10-24 2008-07-31 Matsushita Electric Industrial Co., Ltd. Reference voltage generation circuit

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Application publication date: 20130313