CN102279611A - Variable-curvature compensated bandgap voltage reference source - Google Patents

Abstract

The invention discloses a variable-curvature compensated bandgap voltage reference source, comprising a startup circuit, a PTAT current generating circuit and a high-order temperature compensation circuit, wherein the startup circuit is used to start the PTAT current generating circuit, the PTAT current generating circuit is used to generate a PTAT current which is inputted to the high-order temperature compensation circuit, and the high-order temperature compensation circuit is used to generate a current with high-order temperature characteristics. The current is superimposed with the PTAT current, so as to obtain the reference voltage. In the invention, high-order temperature compensation of the reference voltage is realized by the GSC technology, and the compensation order degree is changed along with the temperature change. The conventional first-order compensation mode is adopted under the low temperature condition, second-order compensation is realized under the medium temperature condition, and third-order compensation is achieved under the high temperature condition. The voltage reference source of the invention is capable of working normally when the power supply voltage is as low as 1.9V, satisfying the requirement of supplying power to a low power supply by an integrated circuit.

Description

A kind of bandgap reference voltage source of variable curvature compensation

Technical field

The invention belongs to power technique fields, the design of particularly a kind of voltage-reference (Voltage Reference).

Background technology

Voltage-reference is as the requisite part of integrated circuit, for entire chip provides bias current and a reference voltage is provided.The size of bias current has determined the power consumption situation of entire chip, simultaneously in chip, a lot of error amplifiers and comparer all be with reference voltage as reference voltage, the degree of stability of voltage-reference has determined the realization of function of chip and the quality of performance to a great extent.

The most frequently used voltage-reference is the bandgap reference voltage source based on triode.As shown in Figure 1, because the clamping action of error amplifier, make V _XWith V _Y2 voltage is equal substantially, i.e. V _X=V _Y=V _BE2, simultaneously, the electric current that is same as in the two-way also equates then have

Because

Then electric current is for being proportional to absolute temperature (PTAT, Proporational To Absolute Temperature) electric current, and this electric current becomes the bias current of entire chip through after the mirror image of current mirror.

According to the expression formula of electric current, can draw band gap voltage and be:

Because V _TBe positive temperature coefficient (PTC), simultaneously V _BE2Be negative temperature coefficient, reasonably adjustment factor

Size, can realize at a certain temperature that just benchmark is zero with variation of temperature, thereby vary with temperature very little reference voltage for entire chip provides one.

Yet the first compensation phase technology has just been adopted in traditional bandgap reference voltage source, however V _BEIn but comprise parameter to the temperature variation high-order, therefore can only accomplish 20 to 100ppm/ ℃ to the temperature coefficient of output voltage, generally be difficult to be lower than 20ppm/ ℃.Simultaneously, now along with development of integrated circuits, supply voltage is more and more lower, requires voltage-reference under low pressure to finish and starts and operate as normal.

Summary of the invention

The objective of the invention is to have proposed a kind of bandgap reference voltage source of variable curvature compensation in order to solve the problem that existing bandgap reference voltage source exists.

Technical scheme of the present invention is: a kind of bandgap reference voltage source of variable curvature compensation, comprise start-up circuit, PTAT current generating circuit and high-order temperature compensated circuit, wherein, start-up circuit is used to start the PTAT current generating circuit, and the PTAT current generating circuit is used to produce the PTAT electric current, and the PTAT electric current is used to be input to high-order temperature compensated circuit, high-order temperature compensated circuit produces the electric current of high-order temperature characterisitic and superposes with the PTAT electric current, obtains the reference voltage of variable curvature compensation.

Described high-order temperature compensated circuit comprises PMOS pipe, the 2nd PMOS pipe, the one NMOS pipe, first resistance, second resistance, the 3rd resistance, the 4th resistance, the 5th resistance, first triode, second triode, first electric capacity and amplifier, wherein, the source electrode of the one PMOS pipe and substrate all connect outside power supply, its grid connects the output terminal of PTAT current generating circuit, its drain electrode is connected with substrate with the source electrode of a NMOS pipe, be connected with substrate with the grid of the 2nd PMOS pipe simultaneously, the grid of the one NMOS pipe connects the output terminal of amplifier, drain electrode is connected with the source electrode of the 2nd PMOS pipe, the drain electrode of the 2nd PMOS pipe is connected and is connected to outside power supply behind first resistance, source electrode links to each other with second resistance, one end jointly with the drain electrode of a NMOS pipe, the other end of second resistance respectively with the 3rd resistance, one end of the 4th resistance, first triode, the base stage of second triode connects, the 3rd resistance, the other end of the 4th resistance connects the negative sense and the positive input of amplifier respectively, and first triode, the collector of second triode, first triode, second transistor emitter interconnects, and ground connection behind the 5th resistance of connecting, first electric capacity are connected between the negative input and output terminal of amplifier.

Described PTAT current generating circuit comprises the 3rd PMOS pipe, the 4th PMOS pipe, the 2nd NMOS pipe, the 3rd triode, the 4th triode, the 5th triode, the 6th triode, and the 6th resistance;

Described start-up circuit comprises the 3rd NMOS pipe, the 4th NMOS pipe and the 5th PMOS pipe;

Wherein, the grid leak short circuit of the 4th PMOS pipe, and simultaneously with the grid of the 3rd PMOS pipe, the drain electrode of the 4th triode, and the drain electrode of the 3rd NMOS pipe of start-up circuit, the grid of the one PMOS pipe of high-order temperature compensated circuit connects, the 3rd PMOS pipe, the source electrode of the 4th PMOS pipe and substrate all connect outside power supply, the collector of the drain electrode of the 3rd PMOS pipe and the 3rd triode and base stage, the base stage of the 4th triode, the grid of the 6th triode, the NMOS pipe of start-up circuit is connected with the grid of the 5th PMOS pipe, the collector of the emitter of the 3rd triode and the 5th triode, the base stage of the 6th triode connects, the collector of the emitter of the 4th triode and the 6th triode, the base stage of the 5th triode connects, the grounded emitter of the 5th triode, the emitter of the 6th triode ground connection behind the 6th resistance of connecting, the drain electrode of the 2nd NMOS pipe, the equal ground connection of source electrode and substrate;

Wherein, the source electrode of the 5th PMOS pipe and substrate all connect outside power supply, grid is connected with the grid of the 4th NMOS pipe and is connected to the PTAT current generating circuit, the drain electrode of the 5th PMOS pipe is connected with the drain electrode of the 4th NMOS pipe, the grid that connects the 3rd NMOS pipe simultaneously, the drain electrode of the 3rd NMOS pipe is connected to the drain electrode of PTAT current source circuit the 4th PMOS pipe, the source ground of the source electrode of the 3rd NMOS pipe and the 4th NMOS pipe.

The invention has the beneficial effects as follows: the GSC technology has been adopted in the bandgap reference voltage source of variable curvature compensation of the present invention, can provide high-order compensation for benchmark output, the substrate current of a PMOS pipe is the electric current that and temperature are the high order relation in the high-order temperature compensated circuit, and with a NMOS pipe on the PTAT electric current stack flow through, affact on second resistance and the 5th resistance, realization is high-order temperature compensated to reference voltage, and the order number of compensation changes along with variation of temperature, when low temperature, adopt traditional first compensation phase form, during middle temperature, realize the second order compensation, during high temperature, realize the compensation of three rank.In addition, voltage-reference of the present invention can satisfy the requirement of integrated circuit to low power supply power supply being low to moderate the normal work of realization under the supply voltage of 1.9V.

Description of drawings

Fig. 1 is existing common band gap voltage-reference synoptic diagram.

Fig. 2 is the bandgap voltage reference structured flowchart of variable curvature compensation of the present invention.

Fig. 3 is the bandgap voltage reference circuit theory diagrams of variable curvature compensation of the present invention.

Fig. 4 is that the bandgap voltage reference output of variable curvature compensation of the present invention realizes circuit theory diagrams.

Fig. 5 concerns synoptic diagram for the output voltage size of the bandgap voltage reference of the embodiment of the invention with variation of temperature.

Fig. 6 is the minimum input power supply test figure of the bandgap voltage reference of the embodiment of the invention.

Fig. 7 is that the output voltage of bandgap voltage reference of the embodiment of the invention is with the situation of change synoptic diagram of input voltage.

Fig. 8 is the Power Supply Rejection Ratio synoptic diagram of the bandgap voltage reference of the embodiment of the invention.

Embodiment

The present invention is described further below in conjunction with accompanying drawing and specific embodiment.

As shown in Figure 2, the bandgap reference voltage source of variable curvature compensation of the present invention, comprise start-up circuit, PTAT current generating circuit, high-order temperature compensated circuit, wherein, start-up circuit is used to start the PTAT current generating circuit, and the PTAT current generating circuit is used to produce the PTAT electric current, and the PTAT electric current is used to be input to high-order temperature compensated circuit, high-order temperature compensated circuit produces the electric current of high-order temperature characterisitic and superposes with the PTAT electric current, and then obtains the reference voltage of variable curvature compensation.

As shown in Figure 3, high-order temperature compensated circuit comprises PMOS pipe M5, M2, NMOS manages M1, resistance R 1, R2, R3, R4, R5, triode Q1, Q2, capacitor C 1 and amplifier OPAMP, wherein, the source electrode of M5 and substrate all meet outside power vd D, its grid connects the output point of PTAT current source circuit, its drain electrode is connected with substrate with the source electrode of M1, also be connected with substrate simultaneously with the grid of M2, the grid of M1 connects the output terminal of amplifier OPAMP, and drain electrode is connected with the source electrode of M2, is connected on the power supply behind the drain series resistance R1 of M2, its source electrode links to each other with resistance R 2 one ends jointly with the drain electrode of M1, the other end of resistance R 2 respectively with resistance R 3, the end of R4, triode Q1, the base stage of Q2 connects, resistance R 3, the other end of R4 connects the negative sense and the positive input of amplifier respectively, and triode Q1, the collector of Q2, triode Q1, the Q2 emitter interconnects, and ground connection behind the resistance in series R5, and capacitor C 1 is connected between the negative input and output terminal of amplifier OPAMP;

The PTAT current generating circuit comprises PMOS pipe M3, M4, and NMOS manages M6, triode Q3, Q4, Q5, Q6, and resistance R 6.Start-up circuit comprises NMOS pipe MS, MS1, and PMOS manages MS2.

Wherein, the grid leak short circuit of M4, and simultaneously with the grid of M3, the drain electrode of Q4, and the drain electrode of the MS of start-up circuit, the grid of the M5 of high-order temperature compensated circuit connects, M3, the source electrode of M4 and substrate all meet outside power vd D, the drain electrode of M3 and the collector of Q3 and base stage, the base stage of Q4, the grid of M6, the MS1 of start-up circuit is connected with the grid of MS2, the emitter of Q3 and the collector of Q5, the base stage of Q6 connects, the emitter of Q4 and the collector of Q6, the base stage of Q5 connects, the grounded emitter of Q5, ground connection behind the emitter resistance in series R6 of Q6, the drain electrode of M6, the equal ground connection of source electrode and substrate;

The source electrode of MS2 and substrate all meet outside power vd D, grid is connected with the grid of MS1 and is connected to the PTAT current generating circuit, the drain electrode of MS2 is connected with the drain electrode of MS1, the grid that also connects simultaneously MS, the drain electrode of MS is connected to the drain electrode of PTAT current generating circuit M4, and the source electrode of MS and the source electrode of MS1 be ground connection all.

Be operated in the NPN type triode of forward active area, its collector current and base-emitter voltage V _BESatisfy relational expression:

V _BE(T)=V _G0-mV _T-(the V of η-α) _TLn T formula (1)

Wherein m is a temperature independent amount, and α is the coefficient that collector current depends on temperature, V _G0The band gap voltage of silicon during for 0K, η=4-n, n are the dependent coefficient of mobility to temperature, and always between 3 to 4, representative value is 3.45 to the value of η.From formula (1) as can be seen, V _TComprised V among the ln T _BEHigh order amount of nonlinearity to temperature.Therefore, by the high-order term of traditional linear compensation in can not compensation band gap reference voltage.Formula (1) can obtain the temperature differentiate:

$\frac{{\mathrm{dV}}_{\mathrm{BE}}\left(T\right)}{\mathrm{dT}}=-(m+\mathrm{\η}-\mathrm{\α})\frac{k}{q}-(\mathrm{\η}-\mathrm{\α})\frac{k}{q}\ln T$ Formula (2)

From formula (2) as can be seen, V _BEChange rate (ATCR, Absolute Temperature Change Rate) with absolute temperature is not a fixed value, but a temperature variant value.Generally satisfy η＞α, so ATCR increases along with the increase of temperature.

Band-gap reference output of the present invention realizes circuit theory diagrams as shown in Figure 4.Here all resistance all is identical type, and R3 is identical with the R4 resistance.Because the clamping action of operational amplifier OPAMP, triode Q1 has identical current potential with the collector of Q2, therefore flows through R3 and equates with the electric current of R4.GSC triode M2 is operated in weak inversion regime, and its grid and substrate short circuit, therefore, and the source electric current I of M2 _{Source (M2)}Can be divided into two parts, i.e. the body electric current I _{B (M2)}With leakage current I _{D (M2)}The GSC triode here refers to the triode grid and is connected with substrate.

I _{Source (M2)}=I _{D (M2)}+ I _{B (M2)}Formula (3)

In the formula (3): $I_{B\left(M2\right)}=I_S\exp \frac{V_{\mathrm{GS}\left(M2\right)}}{V_T}={\mathrm{GT}}^{\mathrm{\η}}\exp (-\frac{V_{G0}}{V_T})\exp \frac{V_{\mathrm{GS}\left(M2\right)}}{V_T}$ Formula (4)

$I_{D\left(M2\right)}={\mathrm{HT}}^{\mathrm{\η}}\exp \frac{k_1}{V_T}\exp \frac{V_{\mathrm{GS}\left(M2\right)}}{n^{\′}{V}_T}$ Formula (5)

Wherein G and H are temperature independent amount, n '=1+C _Js/ C _Ox, C _JsBe depletion region capacitance, C _OxBe gate capacitance, k ₁=-V _G0-V _OFF/ n ' also is a temperature independent constant.Output reference voltage V as seen in Figure 4 _REFSize be:

V _REF=V _{BE (Q2)}+ (R ₂+ R ₅) * I _PTAT+ (R ₂+ R ₅) * I _{D (M2)}Formula (6)

In the formula (6), I _PTATBe the PTAT electric current, first in the expression formula is traditional first compensation phase of band-gap reference with second, last (R ₂+ R ₅) * I _{D (M2)}Be used for compensating V _BEIn the high order amount of nonlinearity.

Obtain by Kirchhoff's law:

I _PTAT=I _{B (M2)}+ I _{D (M1)}Formula (7)

Triode M1 is biased in the forward active area, its leakage current I _{D (M1)}For:

$I_{D\left(M1\right)}=\frac{{\mathrm{\&beta;}}_{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">M</figure-callout>}1}}{2}{(V_{\mathrm{SG}\left(M1\right)}-|V_{\mathrm{THP}}\left|\right)}^2$ Formula (8)

In the formula (8), β _M1=μ _pC _OX(W/L) _M1

In order to simplify derivation, suppose I _PTAT=γ V _T, wherein γ is a temperature independent constant, μ _nAnd μ _pTemperature there is identical order, is divided into following two kinds of situations according to different temperature.

A. when temperature is relatively low, the electric current I in the formula (7) _{B (M2)}Than electric current I _{D (M1)}Very little, thus when temperature is relatively low I _{B (M2)}Can ignore.

If make triode M1 be operated in the edge of saturation region, i.e. V by the working point rationally is set _{SG (M1)}-V _TH=V _{SD (M1)}, like this, can obtain V by formula (7) and formula (8) _{GS (M2)}Expression formula be

$V_{\mathrm{GS}\left(M2\right)}=V_{\mathrm{SD}\left(M1\right)}=\sqrt{\frac{2}{{\mathrm{\&beta;}}_{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">M</figure-callout>}1}}{\mathrm{\&gamma;V}}_T}$ Formula (9)

In conjunction with formula (5) and formula (9), the leakage current of M2 is

$I_{D\left(M2\right)}={\mathrm{HT}}^{\mathrm{\&eta;}}\exp (\frac{k_1}{V_T}+\sqrt{\frac{k_2}{T^{\mathrm{\&eta;}-3}}})$ Formula (10)

K wherein ₂Be a temperature independent constant, formula (10) can get the temperature differentiate

$\frac{{\mathrm{dI}}_{D\left(M2\right)}}{\mathrm{dT}}={\mathrm{HT}}^{\mathrm{\&eta;}-1}\exp (\frac{k_1}{V_T}+\sqrt{\frac{k_2}{T^{\mathrm{\&eta;}-3}}})\&times;\{\mathrm{\&eta;}-\frac{{\mathrm{<figure-callout\; id="1"\; label="qk"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">qk</figure-callout>}}_1}{\mathrm{dT}}-\frac{1}{2}\sqrt{k_2}(\mathrm{\&eta;}-3){\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">T</figure-callout>}}^{\frac{1}{2}(3-\mathrm{\&eta;})}\}$ Formula (11)

In the formula (11), I _{D (M2)}TC be on the occasion of, and ATCR increases along with the increase of temperature.In conjunction with formula (2) and formula (6), can obtain the second order compensation of band-gap reference.Under lower temperature, first compensation phase can pass through V _{BE (Q2)}(R ₂+ R ₅) * I _PTATRealize, under medium temperature, V _REFMiddle (the R that increases ₂+ R ₅) * I _{D (M2)}Offset V _{BE (Q2)}In the recruitment of ACTR.

If V _{SG (M1)}-V _TH＜V _{SD (M1)}, formula (7) can be expressed as under relatively low temperature:

$\mathrm{\&gamma;}{V}_T=\frac{{\mathrm{\&beta;}}_{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">M</figure-callout>}1}}{2}{[V_{\mathrm{SG}\left(M1\right)}-|V_{\mathrm{THP}}\left|\right]}^2$ Formula (12)

Because β _M1Be negative temperature coefficient, V _{SG (M1)}-| V _THP| can rise along with the increase of temperature, therefore, voltage V _{SD (M1)}Have two kinds of situations, a kind of is steady state value, and another kind is ever-increasing value.

(A1) if voltage V _{SD (M1)}Be steady state value, voltage V _{GS (M2)}It is steady state value.Because k ₃=k ₁+ V _{SD (M1)}/ n ' is provided with k simultaneously ₂=0, then have

$\frac{{\mathrm{dI}}_{D\left(M2\right)}}{\mathrm{dT}}={\mathrm{HT}}^{\mathrm{\&eta;}-1}(\mathrm{\&eta;}-\frac{{\mathrm{<figure-callout\; id="1"\; label="qk"\; filenames="HDA0000060374980000011.png,HDA0000060374980000021.png"\; state="\{\{state\}\}">qk</figure-callout>}}_1}{\mathrm{kT}})\exp \left(\frac{k_3}{V_T}\right)$ Formula (13)

Similarly, I _{D (M2)}TC be positive, and ATCR increases along with the increase of temperature.

(A2) if V _{SD (M1)}Rise, then V _{GS (M2)}Also rise, therefore, I _{D (M2}) TC trend similar to top situation.As long as M1 is operated in the saturation region, band-gap reference just can correctly be worked.Condition V _{SG (M1)}-V _TH≤ V _{SD (M1)}Only can have influence on and make C is zero temperature.

B. when a high relatively temperature, the I in the formula (7) _{B (M2)}Can compare I _{D (M1)}Big is many, so I _{B (M2)}When high temperature, play a major role.In conjunction with formula (4), V _{GS (M2)}Expression formula be

$V_{\mathrm{GS}\left(M2\right)}=V_T\ln \frac{{\mathrm{\&gamma;V}}_T}{{\mathrm{GT}}^{\mathrm{\&eta;}}\exp (-\frac{V_{G0}}{V_T})}$ Formula (14)

Based on formula (5) and formula (14), the leakage current of M2 can be expressed as

$I_{D\left(M2\right)}\&ap;{\mathrm{JT}}^{\frac{1}{n^{\&prime;}}}\exp \left(\frac{k_4}{V_T}\right)$ Formula (15)

Wherein J is the constant that is independent of temperature, k ₄=-V _OFF/ n '.Formula (15) can obtain the temperature differentiate

$\frac{{\mathrm{dI}}_{D\left(M2\right)}}{\mathrm{dT}}=(\frac{J}{n^{\&prime;}}{T}^{\frac{1}{n^{\&prime;}}-1}-\frac{{\mathrm{Jqk}}_4}{k}{T}^{\frac{1}{n^{\&prime;}}-2})\exp \frac{k_4}{V_T}$ Formula (16)

Because n ' is bigger slightly than 1, and k ₄Be negative value, so I in the formula (16) _{D (M2)}Rate of temperature change be on the occasion of.Yet the value of ATCR reduces along with the increase of temperature, in conjunction with formula (2) and formula (6), output reference voltage V _REFWhen high temperature, can descend.

As can be seen, when low temperature, pass through V _{BE (Q2)}(R ₂+ R ₅) * I _PTATCarry out first compensation phase.In when temperature, TC be just and the ATCR value along with the electric current I of temperature increase _{D (M2)}Be added into V _REFExpression formula in, offset V _{BE (Q2)}In the recruitment of ATCR with temperature, being band-gap reference has increased the second order compensation rate.When higher relatively temperature, TC is for just, but the electric current I that ATCR reduces with temperature _{D (M2)}Be increased to V _REFExpression formula in, therefore, output voltage V _REFCan descend when high temperature, this is the three rank compensation of band-gap reference.Do not increase extra circuit structure, only by a special structure, making the TC of output reference voltage can be 0 under three temperature, and makes the temperature of benchmark output voltage float to reach to minimize.The variable curvature circuit that proposes in the literary composition is by electric current item I _{D (M2)}Realized high-order temperature compensated, I _{D (M2)}The temperature characterisitic that a variation is arranged in whole temperature range.The temperature characterisitic of circuit as shown in Figure 5.

Owing to increased GSC triode M2, this circuit can be under a low-voltage operate as normal, from Fig. 4, can obtain, minimum output voltage expression formula is

V _{DD_minimum}=V _REF+ V _{GS (M2)}+ V _{OV (IPTAT)}Formula (17)

V wherein _{OV (IPTAT)}For the overdrive voltage of PTAT current source, at I _PTATCurrent source is under the situation of single tube, and its value is typically about 200mV, V _REFBe reference voltage output valve of the present invention, because M2 is biased in weak anti-type state, V _{GS (M2)}Value is less than V _THN, in addition, the bulk potential of M2 is bigger than source electric potential, because the threshold voltage that influences M2 of bulk effect can reduce relatively.Can obtain among Fig. 6, minimum power source voltage probably is 1.9V.As can be seen, this reference voltage source can be at operation at low power supply voltage.

Variation to supply voltage is insensitive more, and the performance of reference voltage is also just good more.As shown in Figure 3, output only has two paths, i.e. path1 among Fig. 4 and path2 from the power supply to the benchmark.Because from the decay of drain-to-source, path2 can weaken the influence of mains fluctuations to output significantly.The method of improving PSRR is that to make the PTAT current source be an ideal current source as much as possible.The M3 of PTAT current source of the present invention has identical breadth length ratio and bigger channel length is arranged with M4 and M5, can reduce the channel length modulation effect like this, simultaneously, because the negative feedback of Q3, Q4, Q5, Q6, C is identical with the current potential of 2 of D, can improve PSRR, the filter action of the M6 of electric capacity connection has also improved PSRR to a certain extent in addition.Can see among Fig. 7 that when supply voltage changed in 1.9 to 5V the scope, output voltage had probably only become 0.001V.Can obtain among Fig. 8, when being lower than 1KHz, PSRR when 10KHz, still has the PSRR up to 58.5dB up to 70.5dB.

In the PTAT current source circuit, in order to keep the electric current unanimity in the two-way, current-mirror structure has adopted relatively big size, to reduce the influence of Early effect as much as possible, can increase their matching simultaneously.Q3, Q4, Q5, Q6 adopt the connection as Fig. 3, form negative feedback loop, and the C point is equated with the current potential that D is ordered.M6 is the electric capacity connected mode, can serve as the dominant pole of loop on the one hand, can serve as filter capacitor on the other hand.Because the current potential that C, D are 2 is identical, the voltage swing above the resistance R 6 is

V _R6=V _BE5-V _BE6=V _TLn M formula (18)

In the formula (18), M is Q6 and the ratio of the number of Q5, and the PTAT size of current is thus

$I_{\mathrm{PTAT}}=I_{R6}=\frac{V_{\mathrm{BE}5}-V_{\mathrm{BE}6}}{R_6}=\frac{V_T\ln M}{R_6}$ Formula (19)

Here, when start-up circuit starts, because the current potential that A is ordered is relatively low, then MS2 conducting, the grid current potential that makes MS is for high, thereby make the MS conducting, the B point has just been received earth potential, and this has just formed a current path from M4 to MS, have after the electric current among the MS, to following injection current, make circuit break away from zero condition, enter duty.Then, the A current potential of ordering can rise to 2V _BE, make the MS1 conducting, the grid current potential of MS is pulled down to ground, thereby close MS, start-up circuit is no longer exerted an influence to the PTAT current source circuit of back, startup is finished.Finish after the startup, than under the condition with higher, though MS1 and MS2 conducting simultaneously, because the breadth length ratio of MS2 is very little, therefore the electric current that flows through is also very little at supply voltage.

The present invention can be applicable in the chip of BiCMOS and CDMOS technology, for entire chip is carried bias current and reference voltage.Owing to adopted the variable curvature compensation, make the benchmark output voltage have very high stability, because circuit satisfies the requirement of low voltage operating, make the present invention that accommodation very widely be arranged simultaneously.

Those of ordinary skill in the art will appreciate that embodiment described here is in order to help reader understanding's principle of the present invention, should to be understood that protection scope of the present invention is not limited to such special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combinations that do not break away from essence of the present invention according to these technology enlightenments disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.

Claims (4)

1. the bandgap reference voltage source of variable curvature compensation, it is characterized in that, comprise start-up circuit, PTAT current generating circuit and high-order temperature compensated circuit, wherein, start-up circuit is used to start the PTAT current generating circuit, the PTAT current generating circuit is used to produce the PTAT electric current, the PTAT electric current is used to be input to high-order temperature compensated circuit, and high-order temperature compensated circuit produces the electric current of high-order temperature characterisitic and superposes with the PTAT electric current, obtains the reference voltage of variable curvature compensation.

2. the bandgap reference voltage source of variable curvature compensation according to claim 1, it is characterized in that, described high-order temperature compensated circuit comprises PMOS pipe, the 2nd PMOS pipe, the one NMOS pipe, first resistance, second resistance, the 3rd resistance, the 4th resistance, the 5th resistance, first triode, second triode, first electric capacity and amplifier, wherein, the source electrode of the one PMOS pipe and substrate all connect outside power supply, its grid connects the output terminal of PTAT current generating circuit, its drain electrode is connected with substrate with the source electrode of a NMOS pipe, be connected with substrate with the grid of the 2nd PMOS pipe simultaneously, the grid of the one NMOS pipe connects the output terminal of amplifier, drain electrode is connected with the source electrode of the 2nd PMOS pipe, the drain electrode of the 2nd PMOS pipe is connected and is connected to outside power supply behind first resistance, source electrode links to each other with second resistance, one end jointly with the drain electrode of a NMOS pipe, the other end of second resistance respectively with the 3rd resistance, one end of the 4th resistance, first triode, the base stage of second triode connects, the 3rd resistance, the other end of the 4th resistance connects the negative sense and the positive input of amplifier respectively, and first triode, the collector of second triode, first triode, second transistor emitter interconnects, and ground connection behind the 5th resistance of connecting, first electric capacity are connected between the negative input and output terminal of amplifier.

3. the bandgap reference voltage source of variable curvature compensation according to claim 2, it is characterized in that, described PTAT current generating circuit, comprise the 3rd PMOS pipe, the 4th PMOS pipe, the 2nd NMOS pipe, the 3rd triode, the 4th triode, the 5th triode, the 6th triode, and the 6th resistance;

Described start-up circuit comprises the 3rd NMOS pipe, the 4th NMOS pipe and the 5th PMOS pipe;

Wherein, the grid leak short circuit of the 4th PMOS pipe, and simultaneously with the grid of the 3rd PMOS pipe, the drain electrode of the 4th triode, and the drain electrode of the 3rd NMOS pipe of start-up circuit, the grid of the one PMOS pipe of high-order temperature compensated circuit connects, the 3rd PMOS pipe, the source electrode of the 4th PMOS pipe and substrate all connect outside power supply, the collector of the drain electrode of the 3rd PMOS pipe and the 3rd triode and base stage, the base stage of the 4th triode, the grid of the 6th triode, the NMOS pipe of start-up circuit is connected with the grid of the 5th PMOS pipe, the collector of the emitter of the 3rd triode and the 5th triode, the base stage of the 6th triode connects, the collector of the emitter of the 4th triode and the 6th triode, the base stage of the 5th triode connects, the grounded emitter of the 5th triode, the emitter of the 6th triode ground connection behind the 6th resistance of connecting, the drain electrode of the 2nd NMOS pipe, the equal ground connection of source electrode and substrate;

Wherein, the source electrode of the 5th PMOS pipe and substrate all connect outside power supply, grid is connected with the grid of the 4th NMOS pipe and is connected to the PTAT current generating circuit, the drain electrode of the 5th PMOS pipe is connected with the drain electrode of the 4th NMOS pipe, the grid that connects the 3rd NMOS pipe simultaneously, the drain electrode of the 3rd NMOS pipe is connected to the drain electrode of PTAT current source circuit the 4th PMOS pipe, the source ground of the source electrode of the 3rd NMOS pipe and the 4th NMOS pipe.

4. the bandgap reference voltage source of variable curvature compensation according to claim 3 is characterized in that, described PMOS pipe, the 2nd PMOS pipe have identical breadth length ratio with the 3rd PMOS pipe.

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