CN203951464U - The electrical source exchange module of Digital Analog Hybrid Circuits a reference source - Google Patents

Abstract

The utility model discloses a kind of electrical source exchange module of Digital Analog Hybrid Circuits a reference source, this electrical source exchange module one input access external power source, output connects band gap reference input, band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input, another input of low pressure difference linearity source of stable pressure output 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.The utility model can disturb, realize high power supply voltage rejection ratio, improve job stability or optimize aspect some in load regulation and improve performance reducing power line and ground wire.

Description

The electrical source exchange module of Digital Analog Hybrid Circuits a reference source

Technical field

The utility model relates to integrated circuit (IC) design technology, relates 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 analog circuit 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 analog signal, and it can bring ground bounce noise and electric source disturbance to whole circuit.These Noise and Interferences are coupled in analog circuit, can affect the service behaviour of analog circuit.Because interference source major part produces by ground wire and power line, and the noise jamming that ground wire causes is maximum, so in Digital Analog Hybrid Circuits layout, extremely important to the design of ground wire and power line.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 analog circuit and digital circuit; cause thus on ground wire and power line and produce interference source, directly affect the service behaviour of analog circuit.

It two is that a reference source will have good accuracy and stability.A reference source be widely used in various analog integrated circuit, 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 converter (DAC), dynamic memory (DRAM), the design of a reference source of low-temperature coefficient, high PSRR (PSRR) is very crucial.Band gap reference is exactly a kind of comparatively stable a reference source, and it is the voltage weighting summation of the voltage of negative temperature coefficient and positive temperature coefficient, 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.

Utility model content

The defect existing for prior art; the purpose of this utility model 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 line and ground wire.

For solving above technical problem, the utility model provides a kind of electrical source exchange module of Digital Analog Hybrid Circuits a reference source, and 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 analog circuit physical isolation, and this analog circuit ground and this digital circuit be segmented in the stratum of zones of different; This Digital Analog Hybrid Circuits a reference source comprises electrical source exchange module, band gap reference and low pressure difference linearity source of stable pressure; Electrical source exchange module one input access external power source, output connects band gap reference input; Band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input; Another input of low pressure difference linearity source of stable pressure output feedback access electrical source exchange module; Band gap reference and low pressure difference linearity source of stable pressure 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 electrical source exchange module one input access external power source, output connects band gap reference input, band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input, another input of low pressure difference linearity source of stable pressure output 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.

Compared with prior art, the utility model can at least can be obtained the advantage of following some aspects:

1, rational deployment analog circuit, digital circuit and power circuit region, between each region, earth connection 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 restriction of the present utility model.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 utility model embodiment modulus hybrid circuit;

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

Fig. 3 is the circuit block diagram of a 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 utility model.But the utility model can be implemented to be much different from alternate manner described here, those skilled in the art can do similar popularization without prejudice to the utility model intension in the situation that, so the utility model is not subject to the restriction of following public specific embodiment.

Referring to Fig. 1, it is the composition frame chart of the utility model embodiment 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 a reference source), digital circuit (as linear digital power circuit, clock circuit, DSP device, CPLD device and FPGA device) and analog circuit (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 line, the inductance elimination that high-frequency conduction noise is wherein connected; The medium and low frequency part of digital circuit and analog circuit is mutually close, far away as far as possible separated of the HFS of digital circuit and analog circuit, and the holding 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 analog circuit and digital circuit in Fig. 1.In above-mentioned modulus hybrid circuit, digital circuit, analog circuit physical isolation, and analog circuit ground and digital circuit be segmented in the stratum of zones of different.Specifically by analog circuit between (layer) and digital circuit ground (layer) use ditch 002 separate, then use connecting line 003 by analog circuit with digital circuit ground bridge joint, separate in this way the ground of analog circuit and digital circuit, can effectively suppress noise.At the present embodiment, reduce analog circuit track lengths, the cabling of digital circuit is along analog circuit cabling as far as possible, and staggered with the VDD-to-VSS of analog circuit.

Referring to Fig. 3, represent the overall structure of a reference source of power circuit in the utility model modulus hybrid circuit.This band gap reference is applied to the Digital Analog Hybrid Circuits (also can be used for analog integrated circuit 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 access external power source of electrical source exchange module 100, its output connects band gap reference 200 inputs, band gap reference 200 output termination low pressure difference linearity source of stable pressure 300 inputs, another input of low pressure difference linearity source of stable pressure 300 output 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 utility model, 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 Digital Logical Circuits, 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 utility model, 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 the utility model a reference source.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 change over switch signal, so that follow-up switching stage circuit optionally accesses external power source or band gap reference, wherein: M4-M7 forms NAND gate, it makes logic judgement, out-put supply change over switch signal to band gap reference enable signal and linear voltage stabilization source output enable signal; M8, M9 form 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 clamp 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 of NAND gate by band gap reference output enable signal inversion; M4-M7 forms NAND gate, and it makes logic judgement to band gap reference enable signal and linear voltage stabilization source output enable signal; The final 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, Digital Logical Circuits partly adopts NAND gate, outputs to switching circuit afterwards through 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, 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 utility model embodiment.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 of amplifier IC jointly, the drain electrode of transistor M18 connects an input of amplifier IC by resistance R 2, the drain electrode of transistor M19 connects another input of amplifier IC by resistance R 3, this resistance R 2 is connected to the collector electrode of triode Q1, the collector electrode 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 electrode of triode Q2 by resistance R 4, the collector electrode 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

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

Referring to Fig. 6, represent the circuit structure of the another kind of band gap reference of the utility model embodiment.This band-gap reference source circuit, is on the basis of Banba structure a 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 part: 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-Reset Signal) 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 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 initial condition 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 electrode of triode VT connects the output of low pressure difference linearity source of stable pressure, the emitter of triode VT connects the input of low pressure difference linearity source of stable pressure, the base stage of triode VT connects the output 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 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.

Operation principle 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 set point, 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 speed.

Referring to Fig. 8, represent the another kind of circuit structure of the utility model low pressure difference linearity source of stable pressure.This low pressure difference linearity source of stable pressure, comprise error amplifying circuit, power stage output circuit and open up increasing bandwidth circuit, wherein: the output negative feedback of power stage 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 of the input connection error amplifying circuit that increases bandwidth circuit, open up the input of the output connection power stage 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 of power stage 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 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 stage 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 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 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 stage 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, compensating 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 preferred implementation of the present utility model, it should be pointed out that above-mentioned preferred implementation should not be considered as restriction of the present utility model, protection range of the present utility model should be as the criterion with claim limited range.For those skilled in the art, within not departing from spirit and scope of the present utility model, can also make some improvements and modifications, these improvements and modifications also should be considered as protection range of the present utility model.

Claims (10)

1. an electrical source exchange module for Digital Analog Hybrid Circuits a reference source, 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 analog circuit physical isolation, and this analog circuit ground and this digital circuit be segmented in the stratum of zones of different; This Digital Analog Hybrid Circuits a reference source comprises electrical source exchange module, band gap reference and low pressure difference linearity source of stable pressure; Electrical source exchange module one input access external power source, output connects band gap reference input; Band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input; Another input of low pressure difference linearity source of stable pressure output feedback access electrical source exchange module; Band gap reference and low pressure difference linearity source of stable pressure 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 electrical source exchange module one input access external power source, output connects band gap reference input, band-gap reference source output terminal connects low pressure difference linearity source of stable pressure input, another input of low pressure difference linearity source of stable pressure output 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.

2. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source 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 change over 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.

3. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 2, it is characterized in that, logic judgement level circuit comprises NAND gate and output inverter, wherein: NAND gate is made logic judgement, out-put supply change over switch signal to band gap reference output enable signal and low pressure difference linearity source of stable pressure output enable signal; Output inverter exports switching stage circuit to after to transfer switch signal inversion.

4. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 2; it is characterized in that; switching stage circuit is connected to protected level device; this protected level device forms a plurality of clamp 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.

5. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 1; it is characterized in that; this band gap reference has the start unit of band-gap reference source unit, band gap reference and the amplifying unit of band gap reference; the start unit of band gap reference can make the self-starting of band gap reference unit, and the amplifying unit of band gap reference can make two input node Level holds of band-gap reference source unit equate.

6. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 5, is characterized in that, the start unit of 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.

7. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 5, it is characterized in that, the amplifying unit of 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 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.

8. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 1, it is characterized in that, low pressure difference linearity source of stable pressure comprises error amplifying circuit, power stage output circuit and opens up increasing bandwidth circuit, the output negative feedback of power stage output circuit is connected to the normal phase input end of error amplifying circuit, the negative-phase input access reference voltage of error amplifying circuit; Open up the input of the output connection power stage output circuit that increases bandwidth circuit, in order to increase the bandwidth of whole feedback loop as second level non-inverting amplifier.

9. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 8, 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 of power stage 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 of error amplifying circuit, the source ground of metal-oxide-semiconductor M28.

10. the electrical source exchange module of Digital Analog Hybrid Circuits a reference source as claimed in claim 8, it is characterized in that, power stage 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 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.