CN104076860A - Band-gap reference source for digital-analog hybrid circuit - Google Patents

Abstract

The invention discloses a band-gap reference source for a digital-analog hybrid circuit. The configuration of the band-gap reference source is that a source electrode of an MOS pipe M18 and a source electrode of an MOS pipe M19 are both connected with a power supply; a gate electrode of the MOS pipe M18 and a gate electrode of the MOS pipe M19 are both connected with the output terminal of an amplifier IC; a drain electrode of the MOS pipe M18 is connected with one input terminal of the amplifier IC through a resistor R2; a drain electrode of the MOS pipe M19 is connected with the other input terminal of the amplifier IC through a resistor R3; the resistor R2 is connected to a collecting electrode of a triode Q1; the collecting electrode of the triode Q1 is connected with a base electrode of the triode Q1; an emitting electrode of the triode Q1 is earthed; the resistor R3 is connected to a collecting electrode of a triode Q2 through a resistor R4; the collecting electrode of the triode Q2 is connected with a base electrode of the triode Q2; an emitting electrode of the triode Q2 is earthed. The band-gap reference source can improve the performances in a certain aspect of reducing interference of power wires and earth wires, realizing the high rejection ratio of the power supply voltage, improving working stability, or optimizing the load regulation.

Description

The band gap reference of Digital Analog Hybrid Circuits

Technical field

The present invention relates to integrated circuit (IC) design technology, relate in particular to Digital Analog Hybrid Circuits (chip) and accessory circuit thereof.

Background technology

At present, Digital Analog Hybrid Circuits obtains applying more and more widely.Owing to there is digital circuit and mimic channel simultaneously, during design, must consider many-sided factor, be hereby exemplified below:

First ground connection is wanted rationally.In Digital Analog Hybrid Circuits, digital signal is a kind of noise source of simulating signal, and it can bring ground bounce noise and electric source disturbance to whole circuit.These Noise and Interferences are coupled in mimic channel, can affect the serviceability of mimic channel.Because interference source major part produces by ground wire and power lead, and the noise that ground wire causes is maximum, so in Digital Analog Hybrid Circuits layout, extremely important to the design of ground wire and power lead.But in the design of traditional Digital Analog Hybrid Circuits; between functional module, physical isolation is inadequate; in analog with digitally fail effectively separated; its Power Management Design does not fully take into account the feature of mimic channel and digital circuit; cause thus on ground wire and power lead and produce interference source, directly affect the serviceability of mimic channel.

It two is that reference source will have good degree of accuracy and stability.Reference source be widely used in various Analogous Integrated Electronic Circuits, digifax mix signal integrate circuit and system integrated chip, its precision and stability directly determines the precision of whole system.In the integrated circuit (IC) design such as A/D converter (ADC), D/A (DAC), dynamic storage (DRAM), the design of the reference source of low-temperature coefficient, high PSRR (PSRR) is very crucial.Band gap reference is exactly a kind of comparatively stable reference source, and it is the voltage weighting summation of the voltage of negative temperature coefficient and positive temperature coefficient (PTC), the impact of compensation temperature on output voltage thus.The feedback control loop that traditional band gap reference need to adopt operational amplifier to form is realized the stable output of voltage-reference, restriction due to operational amplifier self bandwidth, gain, the fluctuation that makes supply voltage (especially time Mid Frequency) in certain bandwidth range cannot well be suppressed, and affects thus the quality of output signals of reference voltage source.In addition, in traditional band-gap reference circuit, output voltage V BE is about 1.25V, and this has just limited the application of supply voltage below 1V.Improved enhancement mode band-gap reference source circuit structure, adopts forward voltage source separately to band gap reference power supply subsequently, make supply-voltage rejection ratio obtain certain raising, but the circuit structure after improving has increased quiescent dissipation and chip area.

In addition, also there is the deficiency of other side in existing Digital Analog Hybrid Circuits, and it awaits optimal design to improve performance.In view of this, be necessary to design a kind of new Digital Analog Hybrid Circuits (chip) and accessory circuit thereof.

Summary of the invention

The defect existing for prior art; the object of the present invention is to provide Digital Analog Hybrid Circuits (chip) and accessory circuit thereof, at least can disturb, realize high power supply voltage rejection ratio, improve job stability or optimize aspect some in load regulation and improve performance reducing power lead and ground wire.

For solving above technical matters, the invention provides a kind of band gap reference of Digital Analog Hybrid Circuits, this Digital Analog Hybrid Circuits comprises power circuit part, artificial circuit part and the digital circuit part being integrated on PCB; This digital circuit and this mimic channel physical isolation, and this mimic channel ground and this digital circuit be segmented in the stratum of zones of different; This Digital Analog Hybrid Circuits reference source comprises electrical source exchange module, band gap reference and low pressure difference linearity source of stable pressure; This band gap reference disposes electrical source exchange module and low pressure difference linearity source of stable pressure, this electrical source exchange module one input end access external power source, output terminal connects band gap reference input end, band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input end, another input end of low pressure difference linearity source of stable pressure output terminal feedback access electrical source exchange module; Band gap reference and low pressure difference linearity source of stable pressure can provide enable signal to electrical source exchange module respectively, in order to electrical source exchange module, after logic judgement, switch powering mode, to band gap reference, provide outer power voltage or low pressure difference linearity source of stable pressure voltage, this band gap reference comprises metal-oxide-semiconductor M18, metal-oxide-semiconductor M19, triode Q1, triode Q2, amplifier IC and resistance R 2, resistance R 3, resistance R 4; The source electrode of the source electrode of metal-oxide-semiconductor M18 and metal-oxide-semiconductor M19 is connected to power supply jointly, the grid of the grid of metal-oxide-semiconductor M18 and metal-oxide-semiconductor M19 connects the output terminal of amplifier IC jointly, the drain electrode of metal-oxide-semiconductor M18 connects an input end of amplifier IC by resistance R 2, the drain electrode of metal-oxide-semiconductor M19 connects another input end of amplifier IC by resistance R 3; This resistance R 2 is connected to the collector of triode Q1, and the collector of this triode Q1 is connected with the base stage of this triode Q1, the grounded emitter of this triode Q1; This resistance R 3 is connected to the collector of triode Q2 by resistance R 4, the collector of this triode Q2 is connected with the base stage of this triode Q2, the grounded emitter of this triode Q2.

Compared with prior art, the present invention can at least can obtain the advantage of following some aspects:

1, rational deployment mimic channel, digital circuit and power circuit region, between each region, ground wire separately, reduces ground wire and Interference from the power supply wire, the larger circuit characteristic that improves circuit board;

2, by comparatively simple electric source modes commutation circuit, can realize the design of high power supply voltage rejection ratio band-gap reference, meet thus the design requirement of low-power consumption, high power supply voltage rejection ratio;

3, on band gap reference basis, increase self-start circuit unit and amplifier circuit unit, make band gap reference can automatically enter normal operating conditions and increase its stability;

4, for low dropout linear regulator structure, increase the circuit unit of bandwidth, optimized load regulation, can meet compared with the requirement of output voltage stabilization under heavy load electric capacity.

Accompanying drawing explanation

By reading below detailed description of the preferred embodiment, various other advantage and benefits will become cheer and bright for those of ordinary skills.Accompanying drawing is only for the object of preferred implementation is shown, and do not think limitation of the present invention.And in whole accompanying drawing, by identical reference symbol, represent identical parts.In the accompanying drawings:

Fig. 1 is the composition frame chart that originally makes inventive embodiments modulus hybrid circuit;

Fig. 2 is the ground connection schematic diagram of mimic channel and digital circuit in Fig. 1;

Fig. 3 is the circuit block diagram of the reference source in power circuit in Fig. 1;

Fig. 4 is a kind of circuit structure of electrical source exchange module in Fig. 3;

Fig. 5 is a kind of circuit structure of band gap reference in Fig. 3;

Fig. 6 is the another kind of circuit structure of band gap reference in Fig. 3;

Fig. 7 is a kind of circuit structure in the poor linear voltage stabilization of Fig. 3 mesolow source;

Fig. 8 is the another kind of circuit structure in the poor linear voltage stabilization of Fig. 3 mesolow source.

Embodiment

A lot of details have been set forth in the following description so that fully understand the present invention.But the present invention can implement to be much different from alternate manner described here, and those skilled in the art can do similar popularization without prejudice to intension of the present invention in the situation that, so the present invention is not subject to the restriction of following public specific embodiment.

Referring to Fig. 1, it is the composition frame chart of embodiment of the present invention Digital Analog Hybrid Circuits.This embodiment has shown a kind of layout of more rational Digital Analog Hybrid Circuits.This Digital Analog Hybrid Circuits comprises the parts such as power circuit (comprising reference source), digital circuit (as linear digital power circuit, clock circuit, DSP device, CPLD device and FPGA device) and mimic channel (as digital to analog converter, analog to digital converter), and all these circuit modules are all integrated on PCB (printed circuit board (PCB)).On this PCB, there are three dividing layers, comprising GND/POWER layer independently: power circuit, digital circuit part and artificial circuit part physical segmentation are at different isolated areas: the ground wire of three parts is very closely connected in the place near power supply with power lead, the inductance elimination that high-frequency conduction noise is wherein connected; The medium and low frequency part of digital circuit and mimic channel is mutually close, far away as far as possible separated of the HFS of digital circuit and mimic channel, and the signal wire of HFS is positioned as close to connector 001, can improve like this performance of whole circuit.

Referring to Fig. 2, it is the ground connection schematic diagram of mimic channel and digital circuit in Fig. 1.In above-mentioned modulus hybrid circuit, digital circuit, mimic channel physical isolation, and mimic channel ground and digital circuit be segmented in the stratum of zones of different.Specifically by mimic channel between (layer) and digital circuit ground (layer) use ditch 002 separate, then use connecting line 003 by mimic channel with digital circuit ground bridge joint, separate in this way the ground of mimic channel and digital circuit, can effectively suppress noise.At the present embodiment, reduce mimic channel track lengths, the cabling of digital circuit is along mimic channel cabling as far as possible, and staggered with the VDD-to-VSS of mimic channel.

Referring to Fig. 3, represent the one-piece construction of the reference source of power circuit in modulus hybrid circuit of the present invention.This band gap reference is applied to the Digital Analog Hybrid Circuits (also can be used for Analogous Integrated Electronic Circuits or system integrated chip) described in Fig. 1, it mainly comprises three formants, it is electrical source exchange module (Power Supply) 100, band gap reference (Bandgap) 200, low pressure difference linearity source of stable pressure (LDO & COMP) 300, connected mode is: an input end access external power source of electrical source exchange module 100, its output terminal connects band gap reference 200 input ends, band gap reference 200 output termination low pressure difference linearity source of stable pressure 300 input ends, another input end of low pressure difference linearity source of stable pressure 300 output terminal feedback access electrical source exchange modules 100, and band gap reference 200 and low pressure difference linearity source of stable pressure 300 provide enable signal to electrical source exchange module 100 respectively.Below the major function of three unit is described respectively.

As shown in Figure 3, electrical source exchange module 100 is through the judgement of digital logic signal, and automatic switchover powering mode, to band-gap reference source circuit 200, is realized the function in forward voltage source; Band-gap reference source circuit 200 is stablized the reference voltage Switch Output of output Low Drift Temperature coefficient to low pressure difference linearity source of stable pressure 300, for chip internal provides a stable voltage source, and output enable signal Bandgap_OK; Low pressure difference linearity source of stable pressure 300 provides stable supply voltage Vout to electrical source exchange module 100, and output enable signal LDO_OK, realizes the switching of outer power voltage VDD and low pressure difference linearity source of stable pressure 300 output voltages.

As shown in Figure 3, in the present invention, electrical source exchange module 100 mainly realizes the switching between outer power voltage and low pressure difference linearity source of stable pressure 300 output voltages: after external power source powers on, after band gap reference 200 is worked with low pressure difference linearity source of stable pressure 300 is normal, difference output enable signal, pass through afterwards the control of electrical source exchange module 100 DLC (digital logic circuit), electrical source exchange module 100 is switched to low pressure difference linearity source of stable pressure output voltage to band gap reference by outer power voltage.By contrast, the fluctuation ratio outer power voltage of inner low pressure difference linearity source of stable pressure reference voltage is much smaller, has indirectly improved thus the supply-voltage rejection ratio of band gap reference 200.

Electrical source exchange module 100 in the present invention, band gap reference 200, low pressure difference linearity source of stable pressure 300 all can adopt multiple circuit form, below describe respectively.

1, electrical source exchange module

Referring to Fig. 4, represent the circuit structure of electrical source exchange module 100 1 preferred embodiments in reference source of the present invention.The circuit of this electrical source exchange module 100 comprises the elements such as current source IB, enhancement mode metal-oxide-semiconductor M1-M17, resistance R 1, capacitor C 1, diode D1; form respectively thus band gap reference output enable signal input stage circuit, a logic judgement level circuit, switching stage circuit and protected level circuit, below be further described.

Band gap reference output enable signal input stage circuit, by current source IB, enhancement mode metal-oxide-semiconductor M1, M2, M3, resistance R 1, capacitor C 1 form, wherein: current source IB and enhancement mode metal-oxide-semiconductor M1 form band gap reference output enable signal judging circuit; M2 and M3 form negative circuit, so that by band gap reference output enable signal inversion; Resistance R 1 forms delay circuit with capacitor C 1, to will be input to follow-up logic judgement level circuit after the band gap reference output enable signal lag Preset Time after anti-phase.

Logic judgement level circuit, access respectively band gap reference output enable signal Bandgap_OK and low pressure difference linearity source of stable pressure output enable signal LDO_OK, its out-put supply switch signal, so that follow-up switching stage circuit optionally accesses external power source or band gap reference, wherein: M4-M7 forms Sheffer stroke gate, it makes logic judgement, out-put supply switch signal to band gap reference enable signal and linear voltage stabilization source output enable signal; M8, M9 form phase inverter, to transfer switch signal inversion, export afterwards switching stage circuit to.

Switching stage circuit, by switching tube M11, M12, M13, M14, M15, M16, formed, according to the transfer switch signal of logic judgement level circuit output, the corresponding conducting of each M1～M17 or cut-off, to optionally access external power source or low pressure difference linearity source of stable pressure voltage.

Protected level circuit, is provided with three clamping circuits especially, wherein: M10, M17 are enhancement mode PMOS pipe, realizes clamper protection; D1, for protection diode, also plays clamping action.

As shown in Figure 4, the course of work of this electrical source exchange module 100 is: current source IB and enhancement mode metal-oxide-semiconductor M1, formation band gap reference output enable signal judging circuit, and wherein M1 meets pulldown function; M2 and M3 later through resistance R 1 and the delay unit that C1 forms, finally output to the input end of Sheffer stroke gate by band gap reference output enable signal inversion; M4-M7 forms Sheffer stroke gate, and it makes logic judgement to band gap reference enable signal and linear voltage stabilization source output enable signal; The final phase inverter through consisting of M8, M9 of enable signal, is respectively switching tube M11, M12, M13, M14, M15, M16 provide switching signal, realize thus the switching of power supply.

It should be noted that, the circuit structures at different levels in above-described embodiment all can adopt other circuit form to realize.For example, in Fig. 4, DLC (digital logic circuit) partly adopts Sheffer stroke gate, outputs to on-off circuit afterwards through phase inverter, obviously also can adopt other logic circuit structure, for example, directly to replace with door, repeat no more.

As shown in Figure 4, the main logic of this electrical source exchange module 100 is:

(1) band gap reference enable signal Bandgap_OK=" 0 ", during low pressure difference linearity source of stable pressure output enable signal LDO_OK=" 0 ",

Vout＝VIN-VDS _-15-VDS _-17

(2) band gap reference enables letter Bandgap_OK=" 1 ", during low pressure difference linearity source of stable pressure output enable signal LDO_OK=" 1 ",

Vout＝VBIAS-VDS _-12

The present embodiment is by the effect of power switch, and the supply-voltage rejection ratio of reference voltage is greatly improved, and under low frequency 100Hz, can reach 106dB; Under intermediate frequency 100KHz, can reach 55dB.

2, band gap reference

Band gap reference is to obtain temperature independent voltage source, its basic ideas are that the base-emitter voltage VBE with the bipolar triode of negative temperature coefficient is added with different weights from the difference △ VBE with the bipolar triode VBE of positive temperature coefficient (PTC), make the temperature coefficient of △ VBE just offset the temperature coefficient of VBE, obtain a temperature independent reference voltage.

Referring to Fig. 5, it is a kind of circuit structure of band gap reference in the embodiment of the present invention.In this band gap reference, Vref is the reference voltage of output, and VBE is the base-emitter voltage of triode Q1 in Fig. 5; R2, R3, the R4 position in circuit as shown in Figure 5.Particular circuit configurations is: comprise transistor M18, transistor M19, triode Q1, triode Q2, amplifier IC and resistance R 2, resistance R 3, resistance R 4, the source electrode of the source electrode of transistor M18 and transistor M19 is connected to power supply jointly, the grid of the grid of transistor M18 and transistor M19 connects the output terminal of amplifier IC jointly, the drain electrode of transistor M18 connects an input end of amplifier IC by resistance R 2, the drain electrode of transistor M19 connects another input end of amplifier IC by resistance R 3, this resistance R 2 is connected to the collector of triode Q1, the collector of this triode Q1 is connected with the base stage of this triode Q1, the grounded emitter of this triode Q1, this resistance R 3 is connected to the collector of triode Q2 by resistance R 4, the collector of this triode Q2 is connected with the base stage of this triode Q2, the grounded emitter of this triode Q2.

In Fig. 5, circuit working principle is: operational amplifier IC, PMOS pipe M18 and M19 form a negative feedback, and amplifier positive-negative input end voltage is equated.The VBE difference △ VBE of two triode Q1, the Q2 that the ratio of emitter area is n is added in resistance R 2.The input current of amplifier is zero, so the voltage in resistance R 2, R3 is also directly proportional with absolute temperature, can be used for compensating the part reducing with absolute temperature linearity in triode Q1 pipe VBE.Therefore, the value of choose reasonable R3, R4 and n, can obtain temperature independent input voltage

$\mathrm{Verf}=V_{\mathrm{BE}}+(1+\frac{R3}{R4})\frac{\mathrm{kT}}{q}\ln n$

Referring to Fig. 6, represent the circuit structure of the another kind of band gap reference of the embodiment of the present invention.This band-gap reference source circuit, is on the basis of Banba structure reference source, to add self-start circuit and amplifying circuit, and concrete structure is as follows.

As shown in Figure 6, this band gap reference comprises following ingredient: the start unit that first is band gap reference (Start_up Part), and mainly by MSA, MSB, the performance of tri-pipes of MSC decides the self-starting of band-gap reference source unit; Second portion is the amplifying unit (Two-stage Amplifer) of band gap reference, adopts secondary Miller circuit, and obtains bias current from band-gap reference source unit; Third part is band-gap reference source unit, basically identical with the band-gap reference source circuit of Hironori Banba structure.

The advantage applies of the band-gap reference source structure of the present embodiment is in the following aspects:

In this band-gap reference source circuit, there is following characteristics:

(1) Hironori Banba band-gap reference source unit comprises the elements such as NMOS pipe M20, M21, M22 and triode Q3, Q4, resistance R 5, R6, R7 and R8, output reference voltage Vref realizes by pressure drops two electric currents and in resistance R 8: an electric current is directly proportional to the VBE of triode Q3, another is directly proportional to the VBE of triode Q4, the reference current producing is mirrored to output current by metal-oxide-semiconductor M22, by output load resistance R8, determine output reference voltage again, the convenient magnitude of voltage that changes required generation.

(2) in band gap reference amplifier unit, adopt Miller to compensate to increase stability, it comprises metal-oxide-semiconductor MA1, MA2, MA3, MA4, MA5, MA6, MA7 etc., and each node 1～7 position specifically as shown in the figure.The general employings such as Hironori Banba structure be to take the single-stage amplifier that NMOS is difference efferent duct, to reach compared with low supply voltage and need off-gauge depletion device like this, transformational to technique is poor, adopts PMOS pipe M20, M21 to input as difference in the present embodiment.Because amplifier role in circuit is to guarantee equating of node 1,2 voltages, reach core is not had to influential effect.

(3) band gap reference self-starting unit comprises metal-oxide-semiconductor MSA, MSB, MSC, M23, M24, and it makes circuit node also can automatically enter normal operating conditions when degeneracy state.In the present embodiment, by adding the circuit of actuating section, although increased parts number, can make manufacture and start-up course simple and practical.Different with it, in Hironori Banba structure, its self-start method is to adopt an extra pulse (Power On-ResetSignal) to realize, and this is less using in simulation and hybrid circuit.

Below self-starting unit and the amplifier circuit unit of the present embodiment are analyzed.

As shown in Figure 6, the start unit of this band gap reference comprises the open circuit consisting of PMOS pipe MSA, PMOS pipe MSB, PMOS pipe MSC; The source electrode of PMOS pipe MSA connects power supply, the drain electrode of PMOS pipe MSA connects the drain electrode of NMOS pipe MSC and the grid of NMOS pipe MSB, the source ground of the source electrode of the grid of metal-oxide-semiconductor MSA, NMOS pipe MSC and NMOS pipe MSB, the grid of the drain electrode of NMOS pipe MSB, NMOS pipe MSC is connected to respectively the amplifying unit of band gap reference.The start unit of this band gap reference is provided with negative circuit, and the grid of the drain electrode of NMOS pipe MSB, NMOS pipe MSC is connected to the amplifying unit of this band gap reference by this negative circuit

As shown in Figure 6, the amplifying unit of this band gap reference comprises PMOS pipe MA1, PMOS pipe MA2, PMOS pipe MA5, PMOS pipe MA7 and NMOS pipe MA3, NMOS pipe MA4, NMOS pipe MA6; The grid of the grid of PMOS pipe MA1 and PMOS pipe MA2 connects respectively the corresponding input end of band gap reference module, the source electrode of the source electrode of PMOS pipe MA1 and PMOS pipe MA2 connects the drain electrode of PMOS pipe MA5 jointly, the source electrode of PMOS pipe MA5 connects power supply, the grid of PMOS pipe MA5 is connected to the self-starting module of band gap reference, the drain electrode of PMOS pipe MA1 is connected with the grid of NMOS pipe MA4 with the grid of the drain electrode of NMOS pipe MA3, NMOS pipe MA3, the source ground of the source electrode of NMOS pipe MA3 and NMOS pipe MA4, forms first order amplifying circuit; The grid of NMOS pipe MA6 connects the drain electrode of NMOS pipe MA4, between the NMOS pipe grid of MA6 and the drain electrode of metal-oxide-semiconductor MA6, meet capacitor C c, the drain electrode of PMOS pipe MA7 connects the drain electrode of NMOS pipe MA6, PMOS pipe MA7 source electrode connects power supply, the grid of PMOS pipe MA7 connects the substrate of PMOS pipe MA5, forms second level amplifying circuit.The biasing circuit of the amplifying unit of this band gap reference, the bias voltage of this biasing circuit is subject to the output voltage control of the start unit of band gap reference.

In comprising the biasing circuit of M25 pipe and the amplifier of M26 pipe, if the voltage of original state node 2 is 0, there is degeneracy, in environmental stimuli situation, can not work not having.This is unacceptable in actual applications, so must remove degeneracy point.Specifically by 3 metal-oxide-semiconductors, form open circuit: due to the grounded-grid of PMOS pipe MSA, so MSA conducting all the time makes node S level point raise like this; Node S is also the grid of MSB pipe, so the conducting of MSB pipe, and its drain electrode level reduces; If start-up point is PMOS grid like this, this PMOS pipe conducting, circuit can be started working.Finally also must make MSB pipe depart from, when circuit starts normally to work, MSC manages unlatching, so just again makes node 5 level decline, and MSB pipe turn-offs thus, has departed from actuating section.

The amplifying unit Main Function of band gap reference is that the level of two input nodes 1,2 are equated, so as long as gain enough just can, in order to prevent vibration, phase margin is also wanted enough in addition, other indexs are not particular importances.Wherein the core of amplifier act as: MA1, MA2 are first order differential amplification, and MA6 is that amplify the second level, and MA5, MA7 distribute to amplifier section metal-oxide-semiconductor from band gap part bias current.Cc is Miller capacitance, and primary and secondary limit is separated, also can increase phase margin.

3, low pressure difference linearity source of stable pressure

Referring to Fig. 7, a kind of circuit structure of low pressure difference linearity source of stable pressure is shown, by series connection, adjust pipe (triode) VT, sample resistance R9 and R10, the elements such as comparison amplifier A form, the collector of triode VT connects the output terminal of low pressure difference linearity source of stable pressure, the emitter of triode VT connects the input end of low pressure difference linearity source of stable pressure, the base stage of triode VT connects the output terminal of comparison amplifier A, the positive input terminal of comparison amplifier A is connected to the tie point of resistance R 9 and R10, resistance R 9 and resistance R 1 are serially connected with between the output terminal and ground of low pressure difference linearity source of stable pressure, the negative electrode of the negative input termination diode of comparison amplifier A, the plus earth of this diode.

Principle of work is: sampling voltage is added in the normal phase input end of amplifier comparator A, compares with the reference voltage Uin that is added in negative-phase input, and both differences, after comparison amplifier A amplifies, are controlled the pressure drop that pipe VT is adjusted in series connection, thus regulated output voltage.When output voltage U out reduces, the difference of reference voltage and sampling voltage increases, and the drive current of comparison amplifier output increases, and series connection is adjusted tube voltage drop and reduced, thereby output voltage is raise.On the contrary, if output voltage U out surpasses needed setting value, the front wheel driving electric current of comparison amplifier A output reduces, thereby output voltage is reduced.In power supply process, output voltage is proofreaied and correct and is carried out continuously, and the adjustment time is only subject to the restriction of comparison amplifier A and output transistor loop reaction velocity.

Referring to Fig. 8, represent the another kind of circuit structure of low pressure difference linearity source of stable pressure of the present invention.This low pressure difference linearity source of stable pressure, comprise error amplifying circuit, power level output circuit and open up increasing bandwidth circuit, wherein: the output terminal negative feedback of power level output circuit is connected to the normal phase input end of error amplifying circuit, the negative-phase input of error amplifying circuit access reference voltage; Open up the output terminal of the input end connection error amplifying circuit that increases bandwidth circuit, open up the input end of the output terminal connection power level output circuit that increases bandwidth circuit, in order to increase the bandwidth of whole feedback loop as second level non-inverting amplifier.Below each several part circuit unit is described respectively:

Open up in increasing bandwidth circuit and be provided with mirror-image constant flow source, specifically comprise that constant current source IB_1, constant current source IB_2 form, available so that the electric current of opening up in increasing bandwidth circuit of flowing through keeps constant.In addition, also comprise transistor M27, transistor M28 and resistance R 11, wherein transistor M27 and transistor M28 are enhancement mode CMOS pipe, and resistance R 11 is Low Temperature Difference resistance.Concrete annexation is: a termination external power source anode of constant current source IB_1, and the drain electrode of another termination transistor M28, and the drain electrode of transistor M28 is connected with the grid of transistor M27; One end ground connection of constant current source IB_1, the drain electrode of another termination transistor M27, and the drain electrode of transistor M27 is connected with the input end of power level output circuit; The grid of transistor M27 is connected with transistor M27 drain electrode by resistance R 11, and the source electrode of transistor M27 connects power positive end; The grid of transistor M27 connects the output terminal of error amplifying circuit, the source ground of transistor M27.As shown in Figure 2, in low pressure difference linearity source of stable pressure, the electric current of mirror current source IB_1, IB_2, low pressure difference linearity source of stable pressure derives from the mirror image of band gap reference (scheming not shown) output current; Owing to being provided with this, open up increasing bandwidth circuit structure, can increase the bandwidth of whole feedback loop.

Error amplifying circuit adopts two-level operating amplifier VBG, can be as first order gain stage; And enhancement transistor M27, transistor M28, low-temperature coefficient resistance R 11, opening up that constant current stream source IB_1, IB_2 form increases bandwidth circuit as being second level non-inverting amplifier, can finally drive PMOS power transistor MP.

Power level output circuit comprises the capacitor C out that power transistor MP, potential-divider network and the external compensation of P type are used, wherein: the grid of P type power transistor MP connects opens up the output terminal that increases bandwidth circuit, source electrode connects external power source anode, drain electrode is connected to output end of pressure-stabilizing and passes through potential-divider network ground connection, this output end of pressure-stabilizing is provided with pressure welding point PAD, between the output terminal of itself and error amplifying circuit, is connected to capacitor C 3; Capacitor C out is connected between the drain electrode and ground of P type power transistor MP, in order to output voltage voltage regulation filtering; This potential-divider network is specifically by resistance R 12, resistance R 13 and capacitor C 2, wherein resistance R 12 and resistance R 13 are serially connected with between the drain electrode and ground of P type power transistor MP, capacitor C 2 also connects with resistance R 12, and the normal phase input end of error amplifying circuit is connected on the connected node of resistance R 12 and resistance R 13 and is connected to realize negative feedback.

As shown in Figure 8, the dead resistance ESR of the capacitor C out of this power level output circuit peripheral voltage stabilizing output use outside bandwidth at a distance, little on loop stability impact, therefore choose the scope of output capacitance and require not do high requirement, can save system cost thus.

This low pressure difference linearity source of stable pressure whole process that reference voltage is set up after supply voltage VDD powers on is: by comprising amplifier enable signal BG_OK, the switching process of low pressure difference linearity source of stable pressure signal LDO_EN, finally realize the switching of Power supply: when input supply voltage rising, while reaching the minimum operating voltage of band gap reference, band gap reference provides the negative phase end of 1.24V reference voltage to LDO first order operational amplifier, export subsequently BG_OK signal, LDO output voltage rising and surpass the voltage range of the normal work of reference voltage now, and export LDO_EN signal, by electrical source exchange module (shown in Fig. 3), started input supply voltage to be switched to LDO output powering mode again, thereby meet the need of work of reference voltage source, and the voltage of final stable output LDO.

This low pressure difference linearity source of stable pressure is guaranteeing that in enough phase margin situations, unity gain bandwidth can reach nearly 400KHz.During for system level chip; due to interior, be provided with above-mentioned high bandwidth low pressure difference linearity source of stable pressure; can effectively widen source of stable pressure loop bandwidth; when making its feedback loop stable; can meet preferably the requirement of low load regulation; this just contributes to guarantee the precision of reference voltage, promotes the performance of simulation/digital-to-analogue hybrid chip.

Different with it, the feedback loop that existing low pressure difference linearity source of stable pressure is formed by error amplifier, corrective network, power tube, resistor voltage divider network forms.Due to the limit bandwidth of error operational amplifier self and the stability requirement of feedback loop, conventionally loop bandwidth is reduced, generally only there is 100KHz left and right, the performance that reduces to have had a strong impact on load regulation of its loop bandwidth.As can be seen here, this low pressure difference linearity source of stable pressure can effectively be widened source of stable pressure loop bandwidth, when making its feedback loop stable, can meet preferably the requirement of low load regulation.

Below be only the preferred embodiment of the present invention, it should be pointed out that above-mentioned preferred implementation should not be considered as limitation of the present invention, protection scope of the present invention should be as the criterion with claim limited range.For those skilled in the art, without departing from the spirit and scope of the present invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (10)

1. a band gap reference for Digital Analog Hybrid Circuits, this Digital Analog Hybrid Circuits comprises power circuit part, artificial circuit part and the digital circuit part being integrated on PCB; This digital circuit and this mimic channel physical isolation, and this mimic channel ground and this digital circuit be segmented in the stratum of zones of different; This Digital Analog Hybrid Circuits reference source comprises electrical source exchange module, band gap reference and low pressure difference linearity source of stable pressure; This band gap reference disposes electrical source exchange module and low pressure difference linearity source of stable pressure, this electrical source exchange module one input end access external power source, output terminal connects band gap reference input end, band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input end, another input end of low pressure difference linearity source of stable pressure output terminal feedback access electrical source exchange module; Band gap reference and low pressure difference linearity source of stable pressure can provide enable signal to electrical source exchange module respectively, in order to electrical source exchange module, after logic judgement, switch powering mode, to band gap reference, provide outer power voltage or low pressure difference linearity source of stable pressure voltage, it is characterized in that, this band gap reference comprises metal-oxide-semiconductor M18, metal-oxide-semiconductor M19, triode Q1, triode Q2, amplifier IC and resistance R 2, resistance R 3, resistance R 4; The source electrode of the source electrode of metal-oxide-semiconductor M18 and metal-oxide-semiconductor M19 is connected to power supply jointly, the grid of the grid of metal-oxide-semiconductor M18 and metal-oxide-semiconductor M19 connects the output terminal of amplifier IC jointly, the drain electrode of metal-oxide-semiconductor M18 connects an input end of amplifier IC by resistance R 2, the drain electrode of metal-oxide-semiconductor M19 connects another input end of amplifier IC by resistance R 3; This resistance R 2 is connected to the collector of triode Q1, and the collector of this triode Q1 is connected with the base stage of this triode Q1, the grounded emitter of this triode Q1; This resistance R 3 is connected to the collector of triode Q2 by resistance R 4, the collector of this triode Q2 is connected with the base stage of this triode Q2, the grounded emitter of this triode Q2.

2. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 1, is characterized in that, between this mimic channel ground and this digital circuit ground, with ditch, separate, and with connecting line by this mimic channel with this digital circuit bridge joint.

3. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 1, is characterized in that, electrical source exchange module comprises logic judgement level circuit and switching stage circuit; Logic judgement level circuit accesses respectively band gap reference output enable signal and low pressure difference linearity source of stable pressure output enable signal, according to respective logic out-put supply switch signal; Switching stage circuit is according to the corresponding conducting of transfer switch signal or cut-off, in order to optionally to access external power source or low pressure difference linearity source of stable pressure.

4. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 3, it is characterized in that, logic judgement level circuit comprises Sheffer stroke gate and output phase inverter, wherein: Sheffer stroke gate is made logic judgement, out-put supply switch signal to band gap reference output enable signal and low pressure difference linearity source of stable pressure output enable signal; Output phase inverter exports switching stage circuit to after to transfer switch signal inversion.

5. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 3; it is characterized in that; switching stage circuit is connected to protected level device; this protected level device forms a plurality of clamping circuits, uses so that the waveform top/bottom of transfer switch signal voltage and low pressure difference linearity source of stable pressure output voltage remains within the scope of default DC level.

6. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 3; it is characterized in that; one input end of logic judgement level circuit connects band gap reference output enable signal input stage circuit; this band gap reference output enable signal input stage circuit comprises band gap reference output enable signal judging circuit and input inversion circuit; this band gap reference output enable signal judging circuit output band gap reference output enable signal, afterwards input end to logic judgement level circuit through input inversion circuit anti-phase input.

7. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 1, it is characterized in that, this low pressure difference linearity source of stable pressure comprises error amplifying circuit and power level output circuit, the output terminal negative feedback of described power level output circuit is connected to the normal phase input end of described error amplifying circuit, the negative-phase input access reference voltage of described error amplifying circuit; This low pressure difference linearity source of stable pressure also comprises opens up increasing bandwidth circuit, the described input end of opening up increasing bandwidth circuit connects the output terminal of described error amplifying circuit, the described output terminal of opening up increasing bandwidth circuit connects the input end of described power level output circuit, in order to increase the bandwidth of whole feedback loop as second level non-inverting amplifier.

8. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 7, it is characterized in that, open up increasing bandwidth circuit and comprise constant current source IB_1, constant current source IB_2, metal-oxide-semiconductor M27, metal-oxide-semiconductor M28 and resistance R 11, wherein: a termination external power source anode of constant current source IB_1, the drain electrode of another termination metal-oxide-semiconductor M28, and the drain electrode of metal-oxide-semiconductor M28 is connected with the grid of metal-oxide-semiconductor M27; One end ground connection of constant current source IB_2, the drain electrode of another termination metal-oxide-semiconductor M27, and the drain electrode of metal-oxide-semiconductor M27 is connected with the input end of power level output circuit; The grid of metal-oxide-semiconductor M27 is connected with the drain electrode of metal-oxide-semiconductor M27 by resistance R 11, and the source electrode of metal-oxide-semiconductor M27 connects power positive end; The grid of metal-oxide-semiconductor M28 connects the output terminal of error amplifying circuit, the source ground of metal-oxide-semiconductor M28.

9. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 7, it is characterized in that, power level output circuit comprises the capacitor C out that P type power MOS pipe MP, potential-divider network and external compensation are used, wherein: the grid of P type power MOS pipe MP connects opens up the output terminal that increases bandwidth circuit, source electrode connects external power source anode, and drain electrode is connected to output end of pressure-stabilizing and passes through potential-divider network ground connection; Capacitor C out is connected between the drain electrode and ground of P type power MOS pipe MP, in order to output voltage voltage regulation filtering.

10. the band gap reference of Digital Analog Hybrid Circuits as claimed in claim 7, is characterized in that, this error amplifying circuit is two-level operating amplifier.