CN105824349A

CN105824349A - Self-calibration band-gap reference circuit and band-gap reference voltage self-calibration system and method

Info

Publication number: CN105824349A
Application number: CN201610361658.4A
Authority: CN
Inventors: 陈建兴; 贾宏勇
Original assignee: Shanghai Macrogiga Electronics Co Ltd
Current assignee: Shanghai Macrogiga Electronics Co Ltd
Priority date: 2016-05-26
Filing date: 2016-05-26
Publication date: 2016-08-03

Abstract

The invention provides a self-calibration band-gap reference circuit and a band-gap reference voltage self-calibration system and method. The self-calibration band-gap reference circuit at least comprises a first voltage signal generation branch, a second voltage signal generation branch, a first interswitch and an offset-adjustable operational amplifier. According to the self-calibration band-gap reference circuit, on the basis of a traditional band-gap reference circuit, two interswitches are added, and the offset-adjustable function of the operational amplifier is added; through the two interswitches, two input ends of the offset-adjustable operational amplifier can input two voltage signals in an interchange mode, and the band-gap reference voltage is calibrated by adjusting the offset voltage of the offset-adjustable operational amplifier. By the adoption of the self-calibration band-gap reference circuit, the structure is simple, offset of most operational amplifiers can be eliminated, and the precision of the band-gap reference voltage is greatly improved.

Description

Self calibration band-gap reference circuit, bandgap voltage reference self-calibration system and method

Technical field

The present invention relates to technical field of integrated circuits, particularly relate to a kind of self calibration band-gap reference circuit, bandgap voltage reference self-calibration system and method.

Background technology

In Analogous Integrated Electronic Circuits, band gap (bandgap) reference circuit is applied widely because of varying with temperature the least.Traditional band-gap reference circuit is as it is shown in figure 1, include: operational amplifier OP, resistance R1, R2, R3, audion Q1, Q2；Assume R3=R2, then its desired output voltage is:

Vbg=Vbe+ (kTlnN/q) * R2/R1,

Wherein, Vbe is the voltage between base stage and the emitter stage of audion Q1, and k is Boltzmann constant, and T is temperature, and q is unit charge electricity, and N is the number ratio of audion Q2 Yu Q1.

Due to when producing, the limited precision of band-gap reference circuit and the generation of random error, cause operational amplifier OP can produce imbalance (offset), so that resistance ratio produces deviation, Q1 with Q2 produces and does not mates, so that the bandgap voltage reference Vbg of output can produce random error.The main source of error is the imbalance of operational amplifier, if only considering the impact that the imbalance of operational amplifier brings, then the bandgap voltage reference of actual output becomes:

Vbg=Vbe+ (kTlnN/q+Vos) * R2/R1,

Wherein, Vos is the offset voltage of operational amplifier, and due to the existence of Vos, the precision of bandgap voltage reference Vbg is relatively low.If Vos can be got rid of, then the precision of bandgap voltage reference Vbg can be greatly improved.

The most conventional method of amplifier imbalance in band-gap reference of removing is to use copped wave (chopper) circuit, as Chinese patent CN103869867A proposes, by high frequency is modulated in imbalance and low-frequency noise, removed it by low pass filter the most again.But the shortcoming of chopper circuit is it needs clock circuit to work always, which not only adds quiescent dissipation, and the bandgap voltage reference Vbg exported has ripple, and low pass filter is in order to suppress ripple, its bandwidth must ratio relatively low, cause needing the biggest resistance and electric capacity, thus add chip area.Additionally, United States Patent (USP) US5773967A proposes the circuit of a kind of temperature characterisitic being improved band-gap reference by automatic calibrating resistance feedback proportional, but it is not suitable for eliminating the imbalance of operational amplifier.

Therefore, how to eliminate the imbalance of operational amplifier, improve the precision of bandgap voltage reference, be problem demanding prompt solution.

Summary of the invention

The shortcoming of prior art in view of the above, it is an object of the invention to provide a kind of self calibration band-gap reference circuit, bandgap voltage reference self-calibration system and method, for solving in prior art due to the imbalance of operational amplifier, cause the problem that the precision of the bandgap voltage reference that band-gap reference circuit exports is relatively low.

For achieving the above object and other relevant purposes, the present invention provides a kind of self calibration band-gap reference circuit, and described self calibration band-gap reference circuit at least includes:

First voltage signal produces branch road, for providing the first voltage signal；

Second voltage signal produces branch road, for providing the second voltage signal；

First interswitch, its first input end is connected to described first voltage signal and produces branch road, and its second input is connected to described second voltage signal and produces branch road, is used for making described first voltage signal and the described second interchangeable input of voltage signal；

Lack of proper care adjustable operational amplifier, its positive input terminal is connected to the first outfan of described first interswitch, its negative input end is connected to the second outfan of described first interswitch, its outfan is connected to described first voltage signal and produces branch road and described second voltage signal generation branch road, for described first voltage signal and described second voltage signal are carried out operation amplifier, to export bandgap voltage reference, and when described first voltage signal and described second voltage letter exchange input, described bandgap voltage reference is calibrated by adjusting the offset voltage of the adjustable operational amplifier of described imbalance.

Preferably, the adjustable operational amplifier of described imbalance at least includes:

Second interswitch, its first input end is connected to the positive input terminal of the adjustable operational amplifier of described imbalance, its the second input is connected to the negative input end of the adjustable operational amplifier of described imbalance, for when described first voltage signal and described second voltage signal exchange input, the voltage signal that positive input terminal and the negative input end of adjustable for described imbalance operational amplifier access is exchanged, so that the output of the adjustable operational amplifier of described imbalance is stable.

Preferably, described imbalance is adjustable, and operational amplifier also includes: the first current source, the first input PMOS, the second input PMOS, the first NMOS tube size adjustable array, the second NMOS tube size adjustable array, the second current source and the 3rd NMOS tube；

nullDescribed first current source is respectively connected to source electrode and the source electrode of described second input PMOS of described first input PMOS，The negative input end that grid is the adjustable operational amplifier of described imbalance of described first input PMOS，The positive input terminal that grid is the adjustable operational amplifier of described imbalance of described second input PMOS，The drain electrode of described first input PMOS connects the second input and the drain terminal of described first NMOS tube size adjustable array of described second interswitch respectively，The drain electrode of described second input PMOS connects first input end and the drain terminal of described second NMOS tube size adjustable array of described second interswitch respectively，The source of described first NMOS tube size adjustable array and the source ground connection of described second NMOS tube size adjustable array，Second outfan of described second interswitch connects grid end and the grid end of described second NMOS tube size adjustable array of described first NMOS tube size adjustable array respectively，First outfan of described second interswitch connects the grid of described 3rd NMOS tube，The source ground of described 3rd NMOS tube，Described second current source accesses the drain electrode of described 3rd NMOS tube，Using the voltage at the drain electrode of described 3rd NMOS tube as the output voltage of the adjustable operational amplifier of described imbalance.

nullPreferably，Described first NMOS tube size adjustable array at least includes: the first load pipe，N the optional load pipe being connected in parallel with described first load pipe，And the n road gating switch in order to gate described optional load pipe connected one to one with n described optional load pipe，Wherein，N is the natural number more than or equal to 1，N described optional load pipe is connected in parallel according to size order from big to small or from small to large，The described grid of the first load pipe and the grid of n described optional load pipe are connected together as the grid end of described first NMOS tube size adjustable array，The described source electrode of the first load pipe and the source electrode of n described optional load pipe are connected together as the source of described first NMOS tube size adjustable array，The drain electrode of n described optional load pipe connects one end of gating switch described in n road respectively，Described in the drain electrode of described first load pipe and n road, the other end of gating switch is connected together as the drain terminal of described first NMOS tube size adjustable array；

nullDescribed second NMOS tube size adjustable array at least includes: the second load pipe，M the optional load pipe being connected in parallel with described second load pipe，And the m road gating switch in order to gate described optional load pipe connected one to one with m described optional load pipe，Wherein，M is the natural number more than or equal to 1，M described optional load pipe is connected in parallel according to size order from big to small or from small to large，The described grid of the second load pipe and the grid of m described optional load pipe are connected together as the grid end of described second NMOS tube size adjustable array，The described source electrode of the second load pipe and the source electrode of m described optional load pipe are connected together as the source of described second NMOS tube size adjustable array，The drain electrode of m described optional load pipe connects one end of gating switch described in m road respectively，Described in the drain electrode of described second load pipe and m road, the other end of gating switch is connected together as the drain terminal of described second NMOS tube size adjustable array.

Preferably, described first voltage signal generation branch road at least includes: the first resistance, the second resistance, and the second audion；Described second voltage signal produces branch road and at least includes: the 3rd resistance, and the first audion；

One end of described second resistance and one end of described 3rd resistance connect the outfan of the adjustable operational amplifier of described imbalance respectively, the other end of described second resistance connects one end of described first resistance, the other end of described first resistance connects the emitter stage of described second audion, the base stage of described second audion and grounded collector, the other end of described 3rd resistance connects the emitter stage of described first audion, the base stage of described first audion and grounded collector；Described first voltage signal produces branch road and connects voltage node at as second voltage signal as the first voltage signal, described second voltage signal generation branch road using described 3rd resistance and described first audion using the voltage at described first resistance and described second resistance connection node.

Preferably, described self calibration band-gap reference circuit also includes:

Drive output branch road, be connected to the outfan of the adjustable operational amplifier of described imbalance, for exporting described bandgap voltage reference, to realize the fast and stable of described external circuit to outside drives.

For achieving the above object and other relevant purposes, the present invention also provides for a kind of bandgap voltage reference self-calibration system, and described bandgap voltage reference self-calibration system at least includes:

Self calibration band-gap reference circuit as above, for producing the first bandgap voltage reference when accessing first phase signal, produces the second bandgap voltage reference when accessing second phase signal；

Sampling hold circuit, is connected to described self calibration band-gap reference circuit, for respectively described first bandgap voltage reference and described second bandgap voltage reference being sampled and kept, to export the first sampled voltage and the second sampled voltage respectively；

Comparator, is connected to described sampling hold circuit, for comparing described first sampled voltage and described second sampled voltage, and exports comparative result；

Logic control circuit, it is connected to described comparator and described self calibration band-gap reference circuit, for providing described first phase signal or described second phase signal, and trim signal for sending to described self calibration band-gap reference circuit according to described comparative result, to adjust the offset voltage of adjustable operational amplifier of lacking of proper care in described self calibration band-gap reference circuit to calibrate described bandgap voltage reference, trim signal described in until no longer to change, and described first bandgap voltage reference and described second bandgap voltage reference after calibration is same or like.

For achieving the above object and other relevant purposes, the present invention also provides for a kind of bandgap voltage reference method for self-calibrating, uses bandgap voltage reference self-calibration system as above, described bandgap voltage reference method for self-calibrating at least to include:

First phase signal or second phase signal is provided by logic control circuit；

Produced the first bandgap voltage reference by self calibration band-gap reference circuit when accessing described first phase signal, produce the second bandgap voltage reference when accessing described second phase signal；

Respectively by sampling hold circuit described first bandgap voltage reference and described second bandgap voltage reference are sampled and kept, to export the first sampled voltage and the second sampled voltage respectively；

By comparator, described first sampled voltage and described second sampled voltage are compared, and export comparative result；

Sent to described self calibration band-gap reference circuit according to described comparative result by logic control circuit and trim signal, to adjust the offset voltage of adjustable operational amplifier of lacking of proper care in described self calibration band-gap reference circuit；Repeat said method and calibrate described bandgap voltage reference, until described in trim signal and no longer change, and described first bandgap voltage reference and described second bandgap voltage reference after calibration is same or like.

Preferably, self calibration band-gap reference circuit produce the first bandgap voltage reference when accessing described first phase signal, produce the second bandgap voltage reference when accessing described second phase signal, method particularly includes:

Produced branch road by the first voltage signal and the first voltage signal is provided, and provided the second voltage signal by the second voltage signal generation branch road；

When accessing first phase signal, by lacking of proper care, adjustable operational amplifier carries out operation amplifier to described first voltage signal and described second voltage signal, to export the first bandgap voltage reference；

When accessing second phase signal, positive input terminal and the negative input end of the adjustable operational amplifier of described imbalance it is separately input to by the first interswitch after described first voltage signal and described second voltage signal being exchanged, then by the second interswitch in the adjustable operational amplifier of described imbalance, the voltage signal that positive input terminal and the negative input end of adjustable for described imbalance operational amplifier access is exchanged, by the adjustable operational amplifier of described imbalance, described first voltage signal and described second voltage signal through twice exchange is carried out operation amplifier again, to export the second bandgap voltage reference.

Preferably, logic control circuit send to described self calibration band-gap reference circuit according to described comparative result and trim signal, to adjust the offset voltage of adjustable operational amplifier of lacking of proper care in described self calibration band-gap reference circuit；Repeat said method and calibrate described bandgap voltage reference, until described in trim signal and no longer change, and described first bandgap voltage reference and described second bandgap voltage reference after calibration is same or like, method particularly includes:

Determined the positive and negative attribute of the output imbalance of described bandgap voltage reference by logic control circuit according to the first time comparative result of described comparator, and determine to change the first NMOS tube size adjustable array or the size of the second NMOS tube size adjustable array in the adjustable operational amplifier of imbalance；

Sent to described self calibration band-gap reference circuit according to the second time of described comparator and later comparative result by logic control circuit and trim signal, by described self calibration band-gap reference circuit according to described in trim the first NMOS tube size adjustable array or the size of the second NMOS tube size adjustable array in adjustable operational amplifier of lacking of proper care described in signal change, to adjust the offset voltage of the adjustable operational amplifier of described imbalance, thus calibrate described bandgap voltage reference；

Wherein, when calibrating described bandgap voltage reference, successive approximation method is used to make the value of described first bandgap voltage reference and described second bandgap voltage reference move closer to, trim signal described in until no longer to change, and described first bandgap voltage reference and described second bandgap voltage reference after calibration is same or like.

As it has been described above, the self calibration band-gap reference circuit of the present invention, bandgap voltage reference self-calibration system and method, have the advantages that

The self calibration band-gap reference circuit of the present invention, two interswitch are added on the basis of traditional bandgap reference circuit, and add the imbalance adjustable function of operational amplifier, two voltage signals of two interchangeable inputs of input of the adjustable operational amplifier of imbalance are made by two interswitch, and by adjusting the offset voltage of adjustable operational amplifier of lacking of proper care, make bandgap voltage reference be calibrated.Use the self calibration band-gap reference circuit of the present invention, simple in construction, the imbalance of major part operational amplifier can be eliminated, substantially increase the precision of bandgap voltage reference.

The bandgap voltage reference self-calibration system of the present invention, use the self calibration band-gap reference circuit that the present invention is above-mentioned, two bandgap voltage references are produced when accessing two phase signals by this self calibration band-gap reference circuit, by sampling hold circuit the two bandgap voltage reference sampled again and keep, then by comparator, the two bandgap voltage reference is compared, changed the load pipe size lacked of proper care in adjustable operational amplifier again according to the comparative result of comparator by logic control circuit, thus adjust the offset voltage of adjustable operational amplifier of lacking of proper care, the automatic calibration of bandgap voltage reference is realized after repeatedly comparing adjustment.Use the bandgap voltage reference self-calibration system of the present invention, simple in construction, the precision of bandgap voltage reference can be increased substantially, and the automatic calibration of bandgap voltage reference can be completed in chip power up, or the switch automatically calibrated by register controlled by user, does not affect the normal work of chip.It addition, without extra external calibration, save testing cost, and without increasing quiescent dissipation.

The bandgap voltage reference method for self-calibrating of the present invention, use the bandgap voltage reference self-calibration system that the present invention is above-mentioned, two bandgap voltage references are produced when accessing two phase signals by self calibration band-gap reference circuit, by sampling hold circuit the two bandgap voltage reference sampled again and keep, then by comparator, the two bandgap voltage reference is compared, change the load pipe size lacked of proper care in adjustable operational amplifier again according to the comparative result of comparator by logic control circuit, thus adjust the offset voltage of adjustable operational amplifier of lacking of proper care, the automatic calibration of bandgap voltage reference is realized after repeatedly comparing adjustment.Use the bandgap voltage reference method for self-calibrating of the present invention, method is simple, the precision of bandgap voltage reference can be increased substantially, and the automatic calibration of bandgap voltage reference or can be completed in chip power up by register controlled, do not affect the normal work of chip, save testing time and testing cost.

Accompanying drawing explanation

Fig. 1 is shown as the schematic diagram of present invention band-gap reference circuit of the prior art.

Fig. 2 is shown as the schematic diagram of the self calibration band-gap reference circuit of first embodiment of the invention.

Fig. 3 is shown as the first interswitch and the circuit diagram of the second interswitch in the self calibration band-gap reference circuit of first embodiment of the invention.

Fig. 4 is shown as in the self calibration band-gap reference circuit of first embodiment of the invention lacking of proper care the circuit diagram of adjustable operational amplifier.

Fig. 5 is shown as in the self calibration band-gap reference circuit of first embodiment of the invention lacking of proper care the circuit diagram of the first NMOS tube size adjustable array of adjustable operational amplifier.

Fig. 6 is shown as an exemplary circuit diagram of the self calibration band-gap reference circuit of first embodiment of the invention.

Fig. 7 is shown as another exemplary circuit diagram of the self calibration band-gap reference circuit of first embodiment of the invention.

Fig. 8 is shown as the principle schematic of the bandgap voltage reference self-calibration system of second embodiment of the invention.

Fig. 9 is shown as the self calibration schematic flow sheet of the bandgap voltage reference self-calibration system of second embodiment of the invention.

Figure 10 is shown as the schematic flow sheet of the bandgap voltage reference method for self-calibrating of third embodiment of the invention.

Element numbers explanation

1 self calibration band-gap reference circuit

11 first voltage signals produce branch road

12 second voltage signals produce branch road

The 13 adjustable operational amplifiers of imbalance

14 drive output branch road

2 sampling hold circuits

3 comparators

4 logic control circuits

S1～S6, S201～S203, step

S501～S502

Detailed description of the invention

Below by way of specific instantiation, embodiments of the present invention being described, those skilled in the art can be understood other advantages and effect of the present invention easily by the content disclosed by this specification.The present invention can also be carried out by the most different detailed description of the invention or apply, and the every details in this specification can also carry out various modification or change based on different viewpoints and application under the spirit without departing from the present invention.

Referring to Fig. 2～Fig. 5, first embodiment of the invention provides a kind of self calibration band-gap reference circuit.It should be noted that, diagram provided in present embodiment illustrates the basic conception of the present invention the most in a schematic way, component count, shape and size when only showing the assembly relevant with the present invention rather than implement according to reality in the most graphic are drawn, during its actual enforcement, the kenel of each assembly, quantity and ratio can be a kind of random change, and its assembly layout kenel is likely to increasingly complex.

Referring to Fig. 2, the self calibration band-gap reference circuit 1 of present embodiment at least includes: the first voltage signal produces branch road 11, and the second voltage signal produces branch road 12, the first interswitch sw1, and adjustable operational amplifier 13 of lacking of proper care.

Producing branch road 11 for the first voltage signal, it is for providing the first voltage signal.

Producing branch road 12 for the second voltage signal, it is for providing the second voltage signal.

For the first interswitch sw1, its first input end connects the first voltage signal and produces branch road 11, and its second input connects the second voltage signal and produces branch road 12, is used for making the first voltage signal and the interchangeable input of the second voltage signal.

For adjustable operational amplifier 13 of lacking of proper care, it has positive input terminal, negative input end and outfan, its positive input terminal is connected to first outfan of the first interswitch sw1, its negative output terminal is connected to second outfan of the first interswitch sw1, its outfan is connected to the first voltage signal and produces branch road 11 and the second voltage signal generation branch road 12, for the first voltage signal and the second voltage signal are carried out operation amplifier, to export bandgap voltage reference, and when the first voltage signal and the second voltage are believed and exchanged input, bandgap voltage reference is calibrated by adjusting the offset voltage of adjustable operational amplifier 13 of lacking of proper care.

In the present embodiment, adjustable operational amplifier 13 of lacking of proper care at least includes: the second interswitch sw2, its first input end is connected to lack of proper care the positive input terminal of adjustable operational amplifier 13, its second input is connected to lack of proper care the negative input end of adjustable operational amplifier 13, for when the first voltage signal and the second voltage signal exchange input, the voltage signal that positive input terminal and the negative input end of adjustable operational amplifier 13 of lacking of proper care access is exchanged, so that the output of adjustable operational amplifier 13 of lacking of proper care is stable.

Referring to Fig. 3, the structure of the first interswitch sw1 and the second interswitch sw2 is identical, all includes two inputs in1, in2 and two outfans out1, out2, and four branch switch s1～s4.During the first branch switch s1 Guan Bi, first input end in1 and the first outfan out1 connection；During the second branch switch s2 Guan Bi, first input end in1 and the second outfan out2 connection；During the 3rd branch switch s3 Guan Bi, the second input in2 and the first outfan out1 connection；During the 4th branch switch s4 Guan Bi, the second input in2 and the second outfan out2 connection.The self calibration band-gap reference circuit 1 of present embodiment is when accessing first phase signal phase1, and the first branch switch s1 and the 4th branch switch s4 of the first interswitch sw1 and the second interswitch sw2 all close, and remaining branch switch is all opened；When accessing second phase signal phase2, the second branch switch s2 and the 3rd branch switch s3 Guan Bi of the first interswitch sw1 and the second interswitch sw2, remaining branch switch is all opened.

Refer to Fig. 4, in the present embodiment, adjustable operational amplifier 13 of lacking of proper care also includes: the first current source I1, first input PMOS PM1, second input PMOS PM2, first NMOS tube size adjustable array NMX1, the second NMOS tube size adjustable array NMX2, the second current source I2 and the 3rd NMOS tube NM3；nullFirst current source I1 is respectively connected to source electrode and the source electrode of the second input PMOS PM2 of the first input PMOS PM1，The grid of the first input PMOS PM1 is the negative input end of adjustable operational amplifier 13 of lacking of proper care，The grid of the second input PMOS PM2 is the positive input terminal of adjustable operational amplifier 13 of lacking of proper care，The drain electrode of the first input PMOS PM1 connects the second input and the drain terminal of the first NMOS tube size adjustable array NMX1 of the second interswitch sw2 respectively，The drain electrode of the second input PMOS PM2 connects first input end and the drain terminal of the second NMOS tube size adjustable array NMX2 of the second interswitch sw2 respectively，The source of the first NMOS tube size adjustable array NMX1 and the source ground connection of the second NMOS tube size adjustable array NMX2，Second outfan of the second interswitch sw2 connects grid end and the grid end of the second NMOS tube size adjustable array NMX2 of the first NMOS tube size adjustable array NMX1 respectively，First outfan of the second interswitch sw2 connects the grid of the 3rd NMOS tube NM3，The source ground of the 3rd NMOS tube NM3，Second current source I2 accesses the drain electrode of the 3rd NMOS tube NM3，Using the voltage at the drain electrode of the 3rd NMOS tube NM3 as the output voltage of adjustable operational amplifier 13 of lacking of proper care.

nullRefer to Fig. 5，First NMOS tube size adjustable array NMX1 at least includes: the first load pipe NM1，N optional load pipe NM11～NM1n being connected in parallel with the first load pipe NM1，And n road gating switch s11～s1n in order to gate optional load pipe NM11～NM1n connected one to one with n optional load pipe NM11～NM1n，Wherein，N is the natural number more than or equal to 1，N optional load pipe NM11～NM1n is connected in parallel according to size order from big to small or from small to large，The grid of the first load pipe NM1 and the grid of n optional load pipe NM11～NM1n are connected together as the grid end of the first NMOS tube size adjustable array NMX1，The source electrode of the first load pipe NM1 and the source electrode of n optional load pipe NM11～NM1n are connected together as the source of the first NMOS tube size adjustable array NMX1，The drain electrode of n optional load pipe NM11～NM1n connects one end of n road gating switch s11～s1n respectively，The drain electrode of the first load pipe NM1 and the other end of n road gating switch s11～s1n are connected together as the drain terminal of the first NMOS tube size adjustable array NMX1.Wherein, the size of each load pipe is determined by their breadth length ratio, and breadth length ratio is the biggest, and size is the biggest.It should be noted that the first load pipe NM1 is as load pipe essential in the first NMOS tube size adjustable array NMX1, having bigger size, n optional load pipe NM11～NM1n is for being finely adjusted, so size is smaller the size of the first load pipe NM1.In practice, the switch of gating switch s11～s1n can be controlled by external control signal (control signal that such as depositor sends), the scope of the first load pipe NM1 size adjusted as required gates the optional load in n road pipe NM11～NM1n Zhong mono-road or a few road with precision, it is achieved the fine setting of the first load pipe NM1 size.

nullAccordingly，Second NMOS tube size adjustable array NMX2 (not shown) at least includes: the second load pipe NM2，M optional load pipe NM21～NM2m being connected in parallel with the second load pipe NM2，And m road gating switch s21～s2m in order to gate optional load pipe connected one to one with m optional load pipe NM21～NM2m，Wherein，M is the natural number more than or equal to 1，M optional load pipe NM21～NM2m is connected in parallel according to size order from big to small or from small to large，The grid of the second load pipe NM2 and the grid of m optional load pipe NM21～NM2m are connected together as the grid end of the second NMOS tube size adjustable array NMX2，The source electrode of the second load pipe NM2 and the source electrode of m optional load pipe NM21～NM2m are connected together as the source of the second NMOS tube size adjustable array NMX2，The drain electrode of m optional load pipe NM21～NM2m connects one end of m road gating switch s21～s2m respectively，The drain electrode of the second load pipe NM2 and the other end of m road gating switch s21～s2m are connected together as the drain terminal of the second NMOS tube size adjustable array NMX2.Wherein, the size of each load pipe is determined by their breadth length ratio, and breadth length ratio is the biggest, and size is the biggest.It should be noted that the second load pipe NM2 is as load pipe essential in the second NMOS tube size adjustable array NMX2, having bigger size, m optional load pipe NM21～NM2m is for being finely adjusted, so size is smaller the size of the second load pipe NM2.In practice, the switch of gating switch s21～s2m can be controlled by external control signal (control signal that such as depositor sends), the scope of the second load pipe NM2 size adjusted as required gates the optional load in m road pipe NM21～NM2m Zhong mono-road or a few road with precision, it is achieved the fine setting of the second load pipe NM2 size.

It addition, please continue to refer to Fig. 2, in the present embodiment, the first voltage signal produces branch road 11 and at least includes: the first resistance R1, the second resistance R2, and the second audion Q2；Second voltage signal produces branch road 12 and at least includes: the 3rd resistance R3, and the first audion Q1；One end of second resistance R2 and one end of the 3rd resistance R3 connect the outfan of adjustable operational amplifier 13 of lacking of proper care respectively, the other end of the second resistance R2 connects one end of the first resistance R1, the other end of the first resistance R1 connects the emitter stage of the second audion Q2, the base stage of the second audion Q2 and grounded collector, the other end of the 3rd resistance R3 connects the emitter stage of the first audion Q1, the base stage of the first audion Q1 and grounded collector；First voltage signal produces branch road 11 and connects voltage node at as second voltage signal as the first voltage signal, the second voltage signal generation branch road 12 using the 3rd resistance R3 and the first audion Q1 using the voltage at the first resistance R1 and the second resistance R2 connection node.

As an exemplary circuit of the self calibration band-gap reference circuit 1 of present embodiment, as shown in Figure 6, the first voltage signal generation branch road 11 at least includes: the second PMOS PM12, the first resistance R1, the second resistance R2, and the second audion Q2；Second voltage signal produces branch road 12 and at least includes: the first PMOS PM11, the 3rd resistance R3, and the first audion Q1；The grid of the first PMOS PM11 and the second PMOS PM12 connects the outfan of adjustable operational amplifier 13 of lacking of proper care respectively, the source electrode of the first PMOS PM11 and the second PMOS PM12 all accesses supply voltage AVDD, the drain electrode of the second PMOS PM12 connects one end of the second resistance R2, the drain electrode of the first PMOS PM11 connects one end of the 3rd resistance R3, the other end of the second resistance R2 connects one end of the first resistance R1, the other end of the first resistance R1 connects the emitter stage of the second audion Q2, the base stage of the second audion Q2 and grounded collector, the other end of the 3rd resistance R3 connects the emitter stage of the first audion Q1, the base stage of the first audion Q1 and grounded collector；First voltage signal produces branch road 11 and connects voltage node at as second voltage signal as the first voltage signal, the second voltage signal generation branch road 12 using the 3rd resistance R3 and the first audion Q1 using the voltage at the first resistance R1 and the second resistance R2 connection node；This exemplary self calibration band-gap reference circuit 1 is connected the voltage at node as output voltage, output bandgap voltage reference using the drain electrode of the second PMOS PM12 with the second resistance R2.This exemplary circuit adds two dividing potential drop PMOS as current source on the basis of circuit shown in Fig. 2, and compared to the circuit of Fig. 2, its PSRR is more preferable.

Another exemplary circuit as the self calibration band-gap reference circuit 1 of present embodiment, as shown in Figure 7, self calibration band-gap reference circuit 1 also includes: drive output branch road 14, be connected to lack of proper care the outfan of adjustable operational amplifier 13, for to outside drives output bandgap voltage reference, to realize the fast and stable of external circuit.Wherein, the first voltage signal generation branch road 11 at least includes: the second PMOS PM12, the first resistance R1, and the second audion Q2；Second voltage signal produces branch road 12 and at least includes: the first PMOS PM11, and the first audion Q1；Output branch road 14 is driven at least to include: the 3rd PMOS PM13, the 4th resistance R4, and the 3rd audion Q3.nullFirst PMOS PM11、The grid of the second PMOS PM12 and the 3rd PMOS PM13 connects the outfan of adjustable operational amplifier 13 of lacking of proper care respectively，First PMOS PM11、The source electrode of the second PMOS PM12 and the 3rd PMOS PM13 all accesses supply voltage AVDD，The drain electrode of the second PMOS PM12 connects one end of the first resistance R1，The other end of the first resistance R1 connects the emitter stage of the second audion Q2，The base stage of the second audion Q2 and grounded collector，The drain electrode of the first PMOS PM11 connects the emitter stage of the first audion Q1，The base stage of the first audion Q1 and grounded collector，The drain electrode of the 3rd PMOS PM13 connects one end of the 4th resistance R4，The other end of the 4th resistance R4 connects the emitter stage of the 3rd audion Q3，The base stage of the 3rd audion Q3 and grounded collector；First voltage signal produces branch road 11 and connects voltage node at as second voltage signal as the first voltage signal, the second voltage signal generation branch road 12 using the first PMOS PM11 and the first audion Q1 using the voltage at the drain electrode connection node of the first resistance R1 and the second PMOS PM12；This exemplary self calibration band-gap reference circuit 1 is connected the voltage at node as output voltage, output bandgap voltage reference using the drain electrode of the 3rd PMOS PM13 with the 4th resistance R4.Owing under normal circumstances, band-gap reference circuit, when external circuit provides bandgap voltage reference, has bigger parasitic capacitance in external circuit, usual bandgap voltage reference needs the longer time to adjust after being input to external circuit, can be only achieved steady statue；And the circuit that the bandgap voltage reference of this exemplary circuit output is compared to Fig. 2 has certain driving force, external circuit can comparatively fast reach steady statue.

As can be seen here, the self calibration band-gap reference circuit of present embodiment, two interswitch are added on the basis of traditional bandgap reference circuit, and add the imbalance adjustable function of operational amplifier, two voltage signals of two interchangeable inputs of input of the adjustable operational amplifier of imbalance are made by two interswitch, and by adjusting the offset voltage of adjustable operational amplifier of lacking of proper care, make bandgap voltage reference be calibrated.Use the self calibration band-gap reference circuit of present embodiment, simple in construction, the imbalance of major part operational amplifier can be eliminated, substantially increase the precision of bandgap voltage reference.

Refer to Fig. 8, second embodiment of the invention provides a kind of bandgap voltage reference self-calibration system, and bandgap voltage reference self-calibration system at least includes: the self calibration band-gap reference circuit 1 involved by first embodiment of the invention, sampling hold circuit 2, comparator 3, and logic control circuit 4.

For self calibration band-gap reference circuit 1, it, for producing the first bandgap voltage reference Vbg1 when accessing first phase signal, produces the second bandgap voltage reference Vbg2 when accessing second phase signal.Self calibration band-gap reference circuit 1 involved by present embodiment is essentially identical with structure with the function of the self calibration band-gap reference circuit 1 involved by first embodiment of the invention, therefore does not repeats them here.

For sampling hold circuit 2, it is connected to self calibration band-gap reference circuit 1, for respectively the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 being sampled and kept, to export the first sampled voltage Vp and the second sampled voltage Vn respectively.

For comparator 3, it is connected to sampling hold circuit 2, for comparing the first sampled voltage Vp and the second sampled voltage Vn, and exports comparative result Vout.

For logic control circuit 4, it is connected to comparator 3 and self calibration band-gap reference circuit 1, for providing first phase signal or second phase signal, and trim signal for sending to self calibration band-gap reference circuit 1 according to comparative result Vout, to adjust the offset voltage of adjustable operational amplifier 13 of lacking of proper care in self calibration band-gap reference circuit 1 to calibrate bandgap voltage reference, no longer change until trimming signal, and the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 after calibration is same or like.

In the present embodiment, what logic control circuit 4 sent trims value employing a series of binary-coded forms expression of signal trim, at the first NMOS tube size adjustable array NMX1, there is n optional load pipe and n gating switch, and second NMOS tube size adjustable array NMX2 time there is m optional load pipe and m gating switch, each gating switch is required to gate by trimming signal, therefore trims signal and can be expressed as trim<n+m-1:0>.

Self calibration band-gap reference circuit 1 in present embodiment, it produces the first bandgap voltage reference Vbg1 when accessing first phase signal:

Vbg1=Vbe+ (kTlnN/q+Vos) * R2/R1.

Existence due to the offset voltage Vos of operational amplifier, when self calibration band-gap reference circuit 1 accesses second phase signal, two input voltage signals of adjustable operational amplifier 13 of lacking of proper care exchange, produce the second bandgap voltage reference Vbg2, and due to the offset voltage Vos invariant position of operational amplifier, therefore the second bandgap voltage reference Vbg2 can produce change compared to the first bandgap voltage reference Vbg1, and amplitude of variation is Δ Vbg:

Vbg2=Vbe+ (kTlnN/q-Vos) * R2/R1,

Δ Vbg=Vbg2-Vbg1=2Vos*R2/R1.

Therefore, self calibration band-gap reference circuit 1 in present embodiment, can be by the load pipe size in two NMOS tube size adjustable arrays of the adjustment adjustable operational amplifier 13 of imbalance, artificial addition is not mated, for offsetting the imbalance of operational amplifier, final realization is when two input voltage signals of adjustable operational amplifier 13 of lacking of proper care exchange, and bandgap voltage reference Vbg is basically unchanged, Δ Vbg ≈ 0.

Please continue to refer to Fig. 8, the bandgap voltage reference self-calibration system of present embodiment is when calibrating, and its operation principle is as follows:

Assume that self calibration band-gap reference circuit 1 produces the first bandgap voltage reference Vbg1 when accessing first phase signal phase1 (ph1), when accessing second phase signal phase2 (ph2), two input voltage signals are exchanged by the first interswitch sw1, the voltage signal that the positive and negative input of adjustable operational amplifier 13 of lacking of proper care accesses is exchanged by the second interswitch sw2 simultaneously, thus ensure stablizing of system, at this moment produce the second bandgap voltage reference Vbg2.Then, the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 is sampled and keeps by sampling hold circuit 2 respectively, exports the first sampled voltage Vp and the second sampled voltage Vn respectively.Then, the first sampled voltage Vp and the second sampled voltage Vn is compared by comparator 3.

Then, logic control circuit 4 determines to change the first NMOS tube size adjustable array NMX1 or the size of the second NMOS tube size adjustable array NMX2 of adjustable operational amplifier 13 of lacking of proper care in self calibration band-gap reference circuit 1 according to comparator 3 primary comparative result Vout, and comparative result Vout is for determining the positive and negative attribute of the offset voltage of adjustable operational amplifier 13 of lacking of proper care for the first time.Start from second time and comparison below is for offsetting the imbalance of adjustable operational amplifier 13 of lacking of proper care, use Approach by inchmeal (SAR, SuccessiveApproximation) method, the value making the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 is increasingly closer to, no longer change until trimming signal, all bits of i.e. trim value are all determined, the the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 that produce after calibration are essentially identical, thus realize calibrating the purpose of operational amplifier offset.

When offsetting the imbalance of adjustable operational amplifier 13 of lacking of proper care, the switch of gating switch in the first NMOS tube size adjustable array NMX1 and the second NMOS tube size adjustable array NMX2 can be controlled by depositor, it is achieved the change of equivalent dimension.The bit value of adjustable array employing and the size of minimum bit optional load pipe depend on scope and the precision wanting to adjust, and this is correlated with different technique.As a example by 4bit, it is assumed that trim<7:4>for adjusting the size of the second NMOS tube size adjustable array NMX2, trim<3:0>for adjusting the size of the first NMOS tube size adjustable array NMX1.First chip is powered on, as it is shown in figure 9, calibration flow process is as follows automatically:

When calibration starts, the trim<7:0>value of the first NMOS tube size adjustable array NMX1 and the second NMOS tube size adjustable array NMX2 is set to 0, and all of gating switch is all opened.

Then, producing the first bandgap voltage reference Vbg1 when first phase signal phase1 is for high (" 1 "), Vbg1 is sampled and remains behind by sampling hold circuit 2.When second phase signal phase2 is high (" 1 "), two input voltage signals are exchanged by the first interswitch sw1, the voltage signal of the positive and negative input input of adjustable operational amplifier 13 of lacking of proper care is exchanged by the second interswitch sw2 simultaneously, thus ensure stablizing of system, at this moment producing the second bandgap voltage reference Vbg2, Vbg2 is sampled and remains behind by sampling hold circuit 2.

Then, two bandgap voltage references are carried out comparing for the first time by comparator 3, first time compares the positive and negative of the imbalance for determining adjustable operational amplifier 13 of lacking of proper care, and logic control circuit 4 determines to change the first NMOS tube size adjustable array NMX1 or the value of the second NMOS tube size adjustable array NMX2 according to comparator 3 result of the comparison Vout for the first time.If Vout is high, Vbg2>Vbg1 then the most only changes the size of NMX1, trim<7:4>=0000, trim<3:0>=1000；If Vout is low, Vbg2 < Vbg1, then the most only change the size of NMX2.Trim<7:4>=1000, trim<3:0>=0000.

Assume that result of the comparison Vout is height for the first time, carries out second time the most again and compares, determines next trim value according to secondary comparative result Vout.If Vout is high, then trim<7:4>=0000, trim<3:0>=1100；If Vout is low, then trim<7:4>=0000, trim<3:0>=0100.

Assume that result of the comparison Vout is low for the first time, carry out second time the most again and compare, determine next trim value according to secondary comparative result Vout.If Vout is high, then trim<7:4>=1100, trim<3:0>=0000；If Vout is low, then trim<7:4>=0100, trim<3:0>=0000.

Ensuing compare that the rest may be inferred.Making Vbg1 with Vbg2 be increasingly closer to, until all bits of trim value are all determined, Vbg1 with Vbg2 produced after calibration is essentially identical or difference is minimum.

That is, start from second time and comparison below is for offsetting the imbalance of adjustable operational amplifier 13 of lacking of proper care, the method using Approach by inchmeal, the value making the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 becomes closer to, until all bits trimming signal trim value are all determined, the the first bandgap voltage reference Vbg1 produced after calibration and the value of the second bandgap voltage reference Vbg2 are same or like, thus realize the purpose of calibration imbalance adjustable operational amplifier 13 imbalance.

As can be seen here, the bandgap voltage reference self-calibration system of present embodiment, use the self calibration band-gap reference circuit involved by first embodiment of the invention, two bandgap voltage references are produced when accessing two phase signals by this self calibration band-gap reference circuit, by sampling hold circuit the two bandgap voltage reference sampled again and keep, then by comparator, the two bandgap voltage reference is compared, changed the load pipe size lacked of proper care in adjustable operational amplifier again according to the comparative result Vout of comparator by logic control circuit, thus adjust the offset voltage of adjustable operational amplifier of lacking of proper care, the automatic calibration of bandgap voltage reference is realized after repeatedly comparing adjustment.Use the bandgap voltage reference self-calibration system of present embodiment, simple in construction, the precision of bandgap voltage reference can be increased substantially, and the automatic calibration of bandgap voltage reference can be completed in chip power up, or the switch automatically calibrated by register controlled by user, does not affect the normal work of chip.It addition, without extra external calibration, save testing cost, and without increasing quiescent dissipation.

Referring to Figure 10, third embodiment of the invention provides a kind of bandgap voltage reference method for self-calibrating, and this bandgap voltage reference method for self-calibrating at least includes:

Step S1, is provided first phase signal or second phase signal by logic control circuit 4.

Step S2, is produced the first bandgap voltage reference Vbg1 by self calibration band-gap reference circuit 1 when accessing first phase signal, produces the second bandgap voltage reference Vbg2 when accessing second phase signal.

In step s 2, method particularly includes:

Step S201, is produced branch road 11 by the first voltage signal and provides the first voltage signal, and provided the second voltage signal by the second voltage signal generation branch road 12.

Step S202, when accessing first phase signal, by lacking of proper care, adjustable operational amplifier 13 carries out operation amplifier to the first voltage signal and the second voltage signal, to export the first bandgap voltage reference Vbg1.

Step S203, when accessing second phase signal, be separately input to after first voltage signal and the second voltage signal being exchanged by the first interswitch sw1 to lack of proper care the positive input terminal of adjustable operational amplifier 13 and negative input end, then by the second interswitch sw2 lacked of proper care in adjustable operational amplifier 13, the voltage signal that positive input terminal and the negative input end of adjustable operational amplifier 13 of lacking of proper care access is exchanged, the first voltage signal and the second voltage signal through twice exchange is carried out operation amplifier, to export the second bandgap voltage reference Vbg2 by adjustable operational amplifier 13 of lacking of proper care again.S3, is sampled and keeps the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 by sampling hold circuit 2 respectively, to export the first sampled voltage Vp and the second sampled voltage Vn respectively.

Step S4, is compared the first sampled voltage Vp and the second sampled voltage Vn by comparator 3, and exports comparative result Vout.

Step S5, is sent to self calibration band-gap reference circuit 1 according to comparative result Vout by logic control circuit 4 and trims signal, to adjust the offset voltage of adjustable operational amplifier 13 of lacking of proper care in self calibration band-gap reference circuit 1.

In step s 5, method particularly includes:

Step S501, determined the positive and negative attribute of the output imbalance of bandgap voltage reference by logic control circuit 4 according to the first time comparative result Vout of comparator 3, and determine to change the first NMOS tube size adjustable array NMX1 or the size of the second NMOS tube size adjustable array NMX2 in the adjustable operational amplifier 13 of imbalance.

Step S502, sent to self calibration band-gap reference circuit 1 according to the second time of comparator 3 and later comparative result Vout by logic control circuit 4 and trim signal, by self calibration band-gap reference circuit 1 according to trimming the first NMOS tube size adjustable array NMX1 or the size of the second NMOS tube size adjustable array NMX2 in the signal change adjustable operational amplifier 13 of imbalance, to adjust the offset voltage of adjustable operational amplifier 13 of lacking of proper care, thus calibrate bandgap voltage reference.

Step S6, repeat the above steps S1～S5 calibrate bandgap voltage reference, no longer change until trimming signal, and the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 after calibration is same or like.

In step s 6, successive approximation method is used to make the value of the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 move closer to, no longer change until trimming signal, and the first bandgap voltage reference Vbg1 and the second bandgap voltage reference Vbg2 after calibration is same or like.

The step of the most various methods divides, and is intended merely to describe clear, it is achieved time can merge into a step or some step is split, be decomposed into multiple step, as long as comprising identical logical relation, all in the protection domain of this patent；To adding inessential amendment in algorithm or in flow process or introducing inessential design, but do not change the core design of its algorithm and flow process all in the protection domain of this patent.

It is seen that, present embodiment is the embodiment of the method corresponding with the second embodiment, and present embodiment can be worked in coordination enforcement with the second embodiment.The relevant technical details mentioned in second embodiment is the most effective, in order to reduce repetition, repeats no more here.Correspondingly, the relevant technical details mentioned in present embodiment is also applicable in the second embodiment.

As can be seen here, the bandgap voltage reference method for self-calibrating of present embodiment, use the bandgap voltage reference self-calibration system involved by second embodiment of the invention, two bandgap voltage references are produced when accessing two phase signals by self calibration band-gap reference circuit, by sampling hold circuit the two bandgap voltage reference sampled again and keep, then by comparator, the two bandgap voltage reference is compared, change the load pipe size lacked of proper care in adjustable operational amplifier again according to the comparative result of comparator by logic control circuit, thus adjust the offset voltage of adjustable operational amplifier of lacking of proper care, the automatic calibration of bandgap voltage reference is realized after repeatedly comparing adjustment.Use the bandgap voltage reference method for self-calibrating of present embodiment, method is simple, the precision of bandgap voltage reference can be increased substantially, and the automatic calibration of bandgap voltage reference or can be completed in chip power up by register controlled, do not affect the normal work of chip, save testing time and testing cost.

In sum, the self calibration band-gap reference circuit of the present invention, bandgap voltage reference self-calibration system and method, have the advantages that

So, the present invention effectively overcomes various shortcoming of the prior art and has high industrial utilization.

The principle of above-described embodiment only illustrative present invention and effect thereof, not for limiting the present invention.Above-described embodiment all can be modified under the spirit and the scope of the present invention or change by any person skilled in the art.Therefore, art has all equivalence modification or changes that usually intellectual is completed under without departing from disclosed spirit and technological thought such as, must be contained by the claim of the present invention.

Claims

1. a self calibration band-gap reference circuit, it is characterised in that described self calibration band-gap reference circuit at least includes:

Self calibration band-gap reference circuit the most according to claim 1, it is characterised in that described imbalance is adjustable, and operational amplifier at least includes:

Self calibration band-gap reference circuit the most according to claim 2, it is characterized in that, described imbalance is adjustable, and operational amplifier also includes: the first current source, first input PMOS, second input PMOS, first NMOS tube size adjustable array, the second NMOS tube size adjustable array, the second current source and the 3rd NMOS tube；

nullSelf calibration band-gap reference circuit the most according to claim 3，It is characterized in that，Described first NMOS tube size adjustable array at least includes: the first load pipe，N the optional load pipe being connected in parallel with described first load pipe，And the n road gating switch in order to gate described optional load pipe connected one to one with n described optional load pipe，Wherein，N is the natural number more than or equal to 1，N described optional load pipe is connected in parallel according to size order from big to small or from small to large，The described grid of the first load pipe and the grid of n described optional load pipe are connected together as the grid end of described first NMOS tube size adjustable array，The described source electrode of the first load pipe and the source electrode of n described optional load pipe are connected together as the source of described first NMOS tube size adjustable array，The drain electrode of n described optional load pipe connects one end of gating switch described in n road respectively，Described in the drain electrode of described first load pipe and n road, the other end of gating switch is connected together as the drain terminal of described first NMOS tube size adjustable array；

Self calibration band-gap reference circuit the most according to claim 1, it is characterised in that described first voltage signal produces branch road and at least includes: the first resistance, the second resistance, and the second audion；Described second voltage signal produces branch road and at least includes: the 3rd resistance, and the first audion；

Self calibration band-gap reference circuit the most according to claim 1, it is characterised in that described self calibration band-gap reference circuit also includes:

7. a bandgap voltage reference self-calibration system, it is characterised in that described bandgap voltage reference self-calibration system at least includes:

Self calibration band-gap reference circuit as described in any one of claim 1～6, for producing the first bandgap voltage reference when accessing first phase signal, produces the second bandgap voltage reference when accessing second phase signal；

8. a bandgap voltage reference method for self-calibrating, uses bandgap voltage reference self-calibration system as claimed in claim 7, it is characterised in that described bandgap voltage reference method for self-calibrating at least includes:

Bandgap voltage reference method for self-calibrating the most according to claim 8, it is characterized in that, produced the first bandgap voltage reference by self calibration band-gap reference circuit when accessing described first phase signal, produce the second bandgap voltage reference when accessing described second phase signal, method particularly includes:

Bandgap voltage reference method for self-calibrating the most according to claim 8, it is characterized in that, sent to described self calibration band-gap reference circuit according to described comparative result by logic control circuit and trim signal, to adjust the offset voltage of adjustable operational amplifier of lacking of proper care in described self calibration band-gap reference circuit；Repeat said method and calibrate described bandgap voltage reference, until described in trim signal and no longer change, and described first bandgap voltage reference and described second bandgap voltage reference after calibration is same or like, method particularly includes: