CN110350767A - A kind of current sample comparator circuit - Google Patents
A kind of current sample comparator circuit Download PDFInfo
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- CN110350767A CN110350767A CN201910596562.XA CN201910596562A CN110350767A CN 110350767 A CN110350767 A CN 110350767A CN 201910596562 A CN201910596562 A CN 201910596562A CN 110350767 A CN110350767 A CN 110350767A
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of DC power input into DC power output
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The present invention provides a kind of current sample comparator circuit, comprising: current ratio inductor and current comparator.Compared with realizing that the high current of the several hundred milliamperes of power switch tube to several amperes carries out directly with the other threshold current of microampere order, and then it is finally reached the purpose for judging the size of power switch tube current and controlling it.Sampling efficiency, the quality of sampled signal and precision, cost are taken into account, while obtaining efficient sampling efficiency, high sampling quality and inexpensive beneficial effect.
Description
Technical field
The invention belongs to switch power supply current sampling technique field more particularly to a kind of current sample comparator circuits.
Background technique
Since the double -loop control of voltage loop and current loop is to the loop stability of Switching Power Supply and to input ripple
Inhibit that there is special advantage, so the control of Switching Power Supply has been transitioned into present stream from the control of the monocycle of original voltage loop
Capable double -loop control.Due to each period need detect, judgement, control switch electric current size, so how efficient and accurate
Ground detection becomes the project that people constantly study by the size of current of power switch.
Be as shown in Figure 1 commonly by below power tube series resistance pass through function come faradic sample mode
The electric current of rate switching tube generates pressure drop on sampling resistor, which is compared with threshold voltage by comparator and can be determined
The size of constant current, adjusting threshold voltage can control open alive size.The maximum advantage of the mode of this sampling is just
Be it is simple, direct, in the application for being relatively suitble to electric current little, so the field class reference in the ACDC of middle low power is the widest
General, because ACDC input voltage itself is high, corresponding exciting current is with regard to less than normal.But in the biggish ACDC of power and medium function
In the application of the lower DCDC of the input voltage of rate, since exciting current is larger, sampling resistor fever does not only result in Switching Power Supply
Inefficiency, and be easily damaged.The area of sampling resistor is larger, and needing together could be by big by multiple resistor coupled in parallel
Electric current.In the biggish application of electric current, current sample is usually carried out using following three kinds of modes:
The first, by the way of current transformer.As shown in Fig. 2, concatenated below power switch tube is not sampling
Resistance instead a current transformer.Electric current is flowed into from main transformer, is flowed out from secondary side, and the electric current of this outflow is declined
N times is subtracted, the multiple decayed is the ratio between the turn ratio number of mutual inductor main transformer and secondary side.Electric current after proportional decaying recycles electricity
Resistance is just easy to sample.The advantages of this mode is exactly sampling efficiency height, because the internal resistance of mutual inductor coil is small.Disadvantage
It is that such mutual inductor needs magnetic core, volume is not small, it is not easy to it manufactures, it is at high cost.And based on practical experience, in the application
The phenomenon that failing because of open circuit can often occur.
Second, the mode of differential amplification sampling resistor voltage.Such as there is the chip of model INA180 in TI company, can incite somebody to action
It tens times of sampling resistor voltage amplification, is then compared again with the threshold voltage of control size of current, in this case samples electricity
Resistance can exponentially reduce.Why need first then to compare sampled voltage differential amplification with threshold voltage again, rather than handle
Compare threshold value reduces at double, is because the latter greatly drops still with the voltage on sampling resistor directly compared with threshold voltage
The signal-to-noise ratio of low sampling.For example, the original minimum value of threshold voltage in Fig. 3 is 200mV, maximum value is 1V, if threshold value electricity
Pressure is reduced to 1/50, although sampling resistor can also correspondingly reduce 1/50, comparative threshold voltage minimum value becomes 4mV,
Maximum value becomes 20mV, this is very small comparison voltage, the switching noise or resistance generated on sampling resistor to chip
Interference signal on internal path is all likely to be more than this voltage, the shutdown of false triggering power switch tube.First use differential amplification
Device amplifies sampled voltage, since two input ports are connected directly between the both ends of resistance, and in close proximity, interference signal
It is considered as common-mode signal and is suppressed, generates the resistance of amplification factor and portion and matched in the chip, also error is prevented to put
Big device itself generates additional noise, so noise can greatly be inhibited by first carrying out pre-amplification in this way, improves signal-to-noise ratio.
The advantages of this kind of sample mode is exactly to reduce sampling resistor to a certain extent, reduces loss and resistance accounts for plate suqare, the disadvantage is that
The multiple of pre-amplification is limited, and otherwise still has the problem of noise acoustic ratio difference, while the offset voltage pair of difference amplifier
The precision of current sample has direct influence, and the voltage before offset voltage and amplification is in the same order of magnitude.
The third, using dead resistance existing for power MOS pipe source electrode itself or the internal resistance of its own as sampling electricity
It hinders and carrys out faradic size, do not cause unnecessary loss in this way for the additional series resistance of sample rate current, therefore often
Referred to as no loss current samples.As shown in figure 4, being the original that common chip interior integrates LDNMOS one kind chip current sampling section
Block diagram is managed, the sampling resistor RSENSE below power tube is the dead resistance of power tube source metal routing, is inherently present.
The internal resistance of metal routing is very little, so needing pre-amplification sampling to be compared, so that there are second of sample mode is the same
Signal-to-noise ratio the problems such as, simultaneously because the resistance low precision and positive temperature coefficient of metal routing are big, so this electric current is adopted
The low precision of sample, generally except ± 20%.
Be compared to the above various current sample modes and be easy to obtain: each mode has respective advantage and disadvantage, simultaneously
With a same feature, being exactly all is electric current to be converted into voltage, then passes through comparator and current limit size again
Threshold voltage is compared, and such comparator will accomplish high speed and high-precision, requires biggish area and power consumption.
Summary of the invention
In order to solve the above technical problems, the present invention provides a kind of current sample comparator circuit.
In order to which some aspects of the embodiment to disclosure have a basic understanding, simple summary is shown below.It should
Summarized section is not extensive overview, nor to determine key/critical component or describe the protection scope of these embodiments.
Its sole purpose is that some concepts are presented with simple form, in this, as the preamble of following detailed description.
The present invention adopts the following technical scheme:
In some alternative embodiments, a kind of current sample comparator circuit is provided, comprising: for sampling to induced electricity
The current ratio inductor of stream；The current ratio inductor include: power MOS pipe, detection metal-oxide-semiconductor, operational amplifier and with
With current mirror pipe；
Conducting voltage is generated in power MOS pipe conducting internal resistance to induced current, which passes through the fortune
It calculates amplifier to copy in the conducting resistance of the detection metal-oxide-semiconductor, generates follow current, follow current mirror image pipe mirror image institute
It states follow current and generates one and the follow current mirror current source proportional to induced current.
In some alternative embodiments, the current ratio inductor includes: power current input port, control terminal
Mouth, the positive port of voltage input, voltage input negative terminal mouth and sampling mirror current source output port；The positive port of voltage input and
Voltage input negative terminal mouth is connect with positive pole and power cathode respectively, power current input port and control port respectively with electricity
The electric current to be detected provided outside stream ratio inductor is connected with control signal.
In some alternative embodiments, a kind of current sample comparator circuit, further includes: be used for the electricity
The follow current mirror current source of stream ratio inductor output is compared with current threshold and exports the electric current ratio of judging result
Compared with device；The current input terminal mouth of sampling the mirror current source output port and the current comparator of the current ratio inductor
Connection.
In some alternative embodiments, the current comparator includes: current input terminal mouth, threshold current input terminal
Mouth, the positive port of input voltage, input voltage negative terminal mouth and the comparison result output port for exporting judging result；Threshold current
Threshold current signal outside input port and current comparator is connected, the positive port of input voltage and input voltage negative terminal mouth difference
It is connect with positive pole and power cathode.
In some alternative embodiments, the follow current mirror image pipe includes: triode PM1 and triode PM2；It is described
The drain electrode of power MOS pipe is connect with the reverse input end mouth of the operational amplifier；The grid of the power MOS pipe and the inspection
Survey the enable port connection of the grid and the operational amplifier of metal-oxide-semiconductor；The positive input mouth of the operational amplifier and three
The drain electrode of pole pipe PM1 and the drain electrode connection for detecting metal-oxide-semiconductor；The output port of the operational amplifier and the grid of triode PM1
And the grid connection of triode PM2；The positive voltage terminal mouth of the operational amplifier and the source electrode of triode PM1 and triode PM2
Source electrode connection；The source of the voltage negative port of the operational amplifier and the source electrode of the power MOS pipe and the detection metal-oxide-semiconductor
Pole connection；Sampling mirror current source output port of the drain electrode of triode PM2 as the current ratio inductor.
In some alternative embodiments, the current comparator includes: electric current leakage and Schmidt；The electric current leaks defeated
Inbound port is connect with the input port of the Schmidt, and the current input terminal mouth as the current comparator；The electric current
The output port of leakage is connect with Schmidt's voltage input negative terminal mouth；The output port of the Schmidt is as the current comparator
Comparison result output port.
In some alternative embodiments, the current comparator includes: electric current leakage, metal-oxide-semiconductor NM8 and load resistance R1；
The input port of the electric current leakage is connect with the grid of metal-oxide-semiconductor NM8, and the current input terminal mouth as the current comparator；
The output port of the electric current leakage is connect with the source electrode of metal-oxide-semiconductor NM8；The drain electrode of metal-oxide-semiconductor NM8 is connect with load resistance R1 and conduct
The comparison result output port of the current comparator.
In some alternative embodiments, the follow current mirror image pipe includes: triode NM6 and triode NM7；It is described
The grid of power MOS pipe is connect with the enable port of the grid of the detection metal-oxide-semiconductor and the amplifier amplifier；The power
The drain electrode of metal-oxide-semiconductor is connect with the reverse input end of the operational amplifier；The voltage negative port and three poles of the operational amplifier
The source electrode connection of the source electrode and triode NM7 of pipe NM6；Drain electrode and institute of the drain electrode of the power MOS pipe with the detection metal-oxide-semiconductor
State the positive voltage terminal mouth connection of operational amplifier；The grid of triode NM7 and the grid of triode NM6 and the operational amplifier
Output port connection；The positive input of the drain electrode of triode NM6 and the source electrode of triode NM7 and the operational amplifier connects
It connects；Sampling mirror current source output port of the drain electrode of triode NM7 as the current ratio inductor.
In some alternative embodiments, the current comparator include: metal-oxide-semiconductor PM3, metal-oxide-semiconductor PM4, metal-oxide-semiconductor NM9 and
Load resistance R2；The drain electrode of metal-oxide-semiconductor PM4 is connect with the grid of metal-oxide-semiconductor NM9, and is inputted as the electric current of the current comparator
Port；The drain electrode of metal-oxide-semiconductor NM9 is connect with the second port of load resistance R2, and the comparison result as the current comparator
Output port；The grid of metal-oxide-semiconductor PM3 is connect with the drain electrode of metal-oxide-semiconductor PM3；The source electrode of metal-oxide-semiconductor PM3 and the source electrode of metal-oxide-semiconductor PM4 and
The first port of load resistance R2 connects.
The utility model has the advantages that realizing that size is to pacify the sampling of the power current of times rank, and exist with size brought by of the invention
The electric current of the other bias current leakage of microampere order is compared, and takes into account sampling efficiency, the quality of sampled signal and precision, cost, together
When obtain efficient sampling efficiency, high sampling quality and inexpensive beneficial effect.
Detailed description of the invention
Fig. 1 is circuit diagram of the prior art by the direct induced current incoming current sampling of series resistance；
Fig. 2 is the circuit diagram that the prior art carries out current sample by serial mutual inductor；
Fig. 3 is the circuit diagram that the prior art carries out electric current by differential amplification sampling resistor voltage；
Fig. 4 is the circuit diagram that the prior art realizes current sample using the parasitic metal resistance of metal-oxide-semiconductor structure；
Fig. 5 is invention's principle block diagram；
Fig. 6 is the implementing circuit figure of low-voltage end current sample comparator circuit of the present invention；
Fig. 7 is the implementing circuit figure of low-voltage end current sample comparator circuit transistor level of the present invention；
Fig. 8 is the implementing circuit figure of the two-stage zoom comparison of low-voltage end current sample comparator circuit of the present invention；
Fig. 9 is the implementing circuit figure that high voltage end NMOS tube power current of the present invention samples comparator circuit；
Figure 10 is the implementing circuit figure of high voltage end pmos power current sample comparator circuit of the present invention.
Specific embodiment
The following description and drawings fully show specific embodiments of the present invention, so that those skilled in the art's energy
Enough practice them.Other embodiments may include structure, logic, it is electrical, process and other change.Implement
Example only represents possible variation.Unless explicitly requested, otherwise individual components and functionality is optional, and the sequence operated can
With variation.The part of some embodiments and feature can be included in or replace part and the feature of other embodiments.
Embodiment 1:
As shown in Fig. 5 to 8, a kind of current sample comparator circuit is provided, comprising: current ratio inductor 201 and electric current
Comparator 202.It is direct to realize that the high current of the several hundred milliamperes of power switch tube to several amperes and the other threshold current of microampere order carry out
Comparison, and then be finally reached the purpose for judging the size of power switch tube current and controlling it.
Current ratio inductor 201 is for sampling to induced current；Current comparator 202 is used for current ratio inductor
The follow current mirror current source of 201 outputs is compared with current threshold and exports judging result.
Current ratio inductor 201 includes: power MOS pipe NM0, detection metal-oxide-semiconductor NM1, operational amplifier OPA and follows electricity
Traffic mirroring pipe, follow current mirror image pipe include: triode PM1 and triode PM2.It is connected to induced current in power MOS pipe NM0
Conducting voltage is generated in internal resistance, which is copied to by operational amplifier OPA in the conducting resistance of detection metal-oxide-semiconductor NM1,
Follow current is generated, follow current mirror image pipe mirror image follow current generates one and the follow current mirror proportional to induced current
Image current source.
Current ratio inductor 201 includes: power current input port 101, control port 102, the positive port of voltage input
105, voltage input negative terminal mouth 103 and sampling mirror current source output port 104.The positive port 105 of voltage input and voltage input
Negative terminal mouth 103 is connect with positive pole and power cathode respectively, power current input port 101 and control port 102 respectively with
The electric current to be detected provided outside current ratio inductor is connected with control signal.
Current comparator 202 includes: current input terminal mouth 106, threshold current input port 107, the positive port of input voltage
110, input voltage negative terminal mouth 108 and the comparison result output port 109 for exporting judging result.Threshold current input port
107 connect with the threshold current signal outside current comparator, and the positive port 110 of input voltage and input voltage negative terminal mouth 108 divide
It is not connect with positive pole and power cathode.Sampling mirror current source output port 104 is connect with current input terminal mouth 106.
When the Drive_H of the control port 102 of current ratio inductor 201 inputs significant level, current ratio induction
Device 201 receives input current, and electric current is flowed into from power current input port 101, flows out from voltage input negative terminal mouth 103, simultaneously
Current ratio inductor 201 is started to work under the action of 102 signal of control port, exports decline proportional to input power electric current
The induced current subtracted；Current comparator 202 carries out the induced current exported from current ratio inductor 201 and threshold current
Directly relatively, and judging result is exported.
Follow current mirror image pipe includes: triode PM1 and triode PM2.Triode PM1 is injected for follow current, can
For P-type channel metal-oxide-semiconductor, PNP triode can be used in triode or BCD semiconductor technology；Triode PM2 is adopted for mirror image
Sample electric current can be P-type channel metal-oxide-semiconductor, PNP triode can be used in triode or BCD semiconductor technology.
The drain electrode of power MOS pipe NM0 is connect with the reverse input end mouth VN of operational amplifier OPA, and as power current
Input port 101.
The grid of power MOS pipe NMO connects with the grid of detection metal-oxide-semiconductor NM1 and the enable port EN of operational amplifier OPA
It connects, and as control port 102.
The drain electrode of the positive input mouth VP and triode PM1 of operational amplifier OPA and the drain electrode for detecting metal-oxide-semiconductor NM1 connect
It connects.
The output port VO of operational amplifier OPA is connect with the grid of the grid of triode PM1 and triode PM2.
The positive voltage terminal mouth of operational amplifier OPA is connect with the source electrode of the source electrode of triode PM1 and triode PM2, and is made
For the positive port 105 of voltage input.
The voltage negative port of operational amplifier OPA and the source electrode of power MOS pipe NM0 and the source electrode for detecting metal-oxide-semiconductor NM1 connect
It connects, and as voltage input negative terminal mouth 103.
Sampling mirror current source output port 104 of the drain electrode of triode PM2 as current ratio inductor.
Current comparator 202 includes: electric current leakage and Schmidt.The bias current port of electric current leakage is inputted as threshold current
Port 107；The input port of electric current leakage is connect with the input port of Schmidt SMT, and is inputted as the electric current of current comparator
Port 106；The output port of electric current leakage is connect with Schmidt's SMT voltage input negative terminal mouth, and forms input voltage negative terminal mouth
108；The positive port of the voltage input of Schmidt SMT is connect with the positive port 110 of input voltage；The output port conduct of Schmidt SMT
The comparison result output port 109 of current comparator.
Working principle is that, when the control port 102 of current ratio inductor 201 is high level, power MOS pipe NM0 is led
It is logical, power current IinConduction voltage drop is formed by power MOS pipe NM0, while operational amplifier OPA also starts to detect, it is with three
Pole pipe PM1 forms voltage follower, according to the principle of operation amplifier it is found that operational amplifier OPA can control the grid of triode PM1
Pole tension generates certain follow current, which can also flow into detection metal-oxide-semiconductor NM1, finally makes the drain electrode electricity of NM0 and NM1
It presses equal.NM0 and NM1 is same type of various sizes of N-channel transistor, and driving voltage having the same, it is assumed that
The size of NM0 is n times of NM1, and the conducting resistance of NM0 is r0, is readily apparent that the conducting resistance of NM1 is n*r0, by NM0 and NM1
Drain voltage it is equal available:
Iin*r0=IPM1*n*r0；
It is so n/mono- of power current Iin by the follow current of triode PM1.
In order to guarantee the matching precision of NM0 and NM1, i.e., when the size of NM0 is n times of NM1, the conducting resistance of NM1
It is approximately n times of NM0, the size of NM1 cannot be designed too small, otherwise due to device parameters boundary effect caused by undersized
Matching precision is caused to be deteriorated, so multiple n cannot be too big.It is also so no small by the electric current of PM1, for example, passing through power
Electric current 2A, the n=5000 of metal-oxide-semiconductor NM0, the electric current by triode PM1 are 400uA.On the one hand the current value is directly as electricity
The input for flowing comparator is still too big, on the other hand can only flow into detection metal-oxide-semiconductor NM1 by the electric current of triode PM1 so as to it
Drain voltage is equal with power MOS pipe NM0's, and cannot function as the output electric current of current ratio inductor.So needing to utilize
The follow current for passing through triode PM1 with the triode PM2 mirror image of triode PM1 same type again decays current ratio m
Times, and the output electric current as current ratio inductor.It is assumed that m=8, then the multiple decayed in total is mn=400000 times, as
The precision that proportionally decaying twice is greatly improved electric current induction in this way can be made simultaneously because output electric current is reduced to 50uA
For the input current of current comparator.
First illustrate that current source and electric current leak the two technical terms in integrated circuit before illustrating current comparator, as three
The electric current that pole pipe PM2 is generated is flowed into from the positive port of power input, is flowed out from the drain electrode of triode PM2, which can be used as other
The input source signal of circuit, so frequently referred to current source.The metal-oxide-semiconductor NM3 in specific implementation circuit such as Fig. 7 that electric current leaks in Fig. 6,
Electric current is flowed into from the drain electrode of metal-oxide-semiconductor NM3, from source electrode outflow and directly to input voltage negative terminal mouth 108, so it is only to absorb electricity
Stream, seems that the funnel of an electric current is the same, and frequently referred to electric current leaks.
For triode PM2 as input current source, the electric current that metal-oxide-semiconductor NM3 is formed leaks the load end compared as electric current, due to
The small signal impedance of triode PM2 and metal-oxide-semiconductor NM3 are larger, and the one-stage amplifier that they are formed may be implemented tens of or even hundreds of
Gain again, then when the electric current of triode PM2 output is greater than electric current and leaks the electric current that can be absorbed, with the increasing of current differential
Add drain voltage to gradually increase, is finally reached the maximum voltage of power supply.As one-stage amplifier has certain amplification factor, but
Be due to not big enough and to make drain voltage increase not fast enough, so in the application not high for required precision, with Schmidt's handle
Drain voltage waveform is shaped to logic level, can be as the judging result of size of current.As commonly used in integrated circuit in Fig. 7
Schmidt's structure, the electric current of triode PM2 be more than electric current leakage allow by the certain amplitude of current value, Schmidt's output is low
Level indicates that power current is bigger than normal.
Two-stage amplification can also be used in current comparator 202, as shown in Figure 8.Current comparator 202 includes: electric current leakage, MOS
Pipe NM8 and load resistance R1；The input port of electric current leakage is connect with the grid of metal-oxide-semiconductor NM8, and the electric current as current comparator
Input port 106；The output port of electric current leakage is connect with the source electrode of metal-oxide-semiconductor NM8；The drain electrode of metal-oxide-semiconductor NM8 and load resistance R1 mono-
End connection and the comparison result output port 109 as current comparator；The load resistance R1 other end is as input voltage anode
Mouth 110.
Input current and metal-oxide-semiconductor NM3 form first order trans-impedance amplifier, the drain electrode electricity that its amplification output voltage is NM3
Pressure.Second level voltage amplification is made of metal-oxide-semiconductor NM8 and load resistance R1, it is a common-source amplifier, if with tri- pole npn
Pipe replacing metal-oxide-semiconductor NM8 is exactly grounded emitter amplifier, also through replacing load resistance as load frequently with current source in integrated road
R1。
This current sample comparator is used in Switching Power Supply, as long as the output voltage of pressure stabilizing error amplifier controls
The size of threshold current Ith can control its size of current by power MOS pipe switch, and constantly regulate duty ratio makes to switch
The output voltage stabilization of power supply is in setting value.
Embodiment 2:
As shown in Fig. 9 to 10, a kind of current sample comparator circuit is provided, comprising: current ratio inductor 301 and electric current
Comparator 302.Current ratio inductor 301 is for sampling to induced current；Current comparator 302 is for incuding current ratio
The follow current mirror current source that device 301 exports is compared with current threshold and exports judging result.
Current ratio inductor 301 includes: power MOS pipe NM4, detection metal-oxide-semiconductor NM5, operational amplifier OPA and follows electricity
Traffic mirroring pipe, follow current mirror image pipe include: triode NM6 and triode NM7.It is connected to induced current in power MOS pipe NM4
Conducting voltage is generated in internal resistance, which is copied to by operational amplifier OPA in the conducting resistance of detection metal-oxide-semiconductor NM5,
Follow current is generated, follow current mirror image pipe mirror image follow current generates one and the follow current mirror proportional to induced current
Image current source.
Embodiment 1 is embodiment of the present invention in the sampling of voltage low-side current, and voltage low side here refers to power tube
The negative input port of power supply is in sample circuit, such as the source electrode of power MOS pipe NM0 connects power ground, power in Fig. 6
Drain voltage also very little when metal-oxide-semiconductor NM0 is connected, thus positive input of the input common mode voltage of sample rate current relative to power supply
Port voltage is low-voltage.In practice, the present invention can be applied in high-side current sampling, such as common buck topology
Unisolated switch power supply, asymmetrical half-bridge, flyback it is active it is clamped be all the metal-oxide-semiconductor that all there is the driving of high grid, so needing voltage
High-end carry out current sample.
It is the schematic diagram of the present embodiment 2 as shown in Figure 9, it is electric current high-side current sample circuit of the invention.Its end
Mouthful number acted on port effect with port numbering and the port in embodiment 1 be it is identical, which is not described herein again, port 101
For power current input port 101, electric current is flowed out unlike the first embodiment, is equivalent to outflow negative current.Because of function
Rate metal-oxide-semiconductor NM4 is in high voltage end, and drain electrode connects the positive port of power input, and source electrode is also close to the positive port of power input when opening
Voltage；Control port 102 is the driving signal of power MOS pipe NM4 and detection metal-oxide-semiconductor NM5 and the enable signal of amplifier.
When the Drive_H of the control port 102 of current ratio inductor 301 inputs significant level, current ratio induction
Device 301 receives input current, and electric current is flowed into from power current input port 101, flows out from voltage input negative terminal mouth 103, simultaneously
Current ratio inductor 301 is started to work under the action of 102 signal of control port, exports decline proportional to input power electric current
The induced current subtracted；Current comparator 302 carries out the induced current exported from current ratio inductor 301 and threshold current
Directly relatively, and judging result is exported.
The grid of power MOS pipe NM4 connects with the grid of detection metal-oxide-semiconductor NM5 and the enable port EN of amplifier amplifier OPA
It connects, and as control port 102.
The drain electrode of power MOS pipe NM4 is connect with the reverse input end VN of operational amplifier OPA, and defeated as power current
Inbound port 101.
The voltage negative port of operational amplifier OPA is connect with the source electrode of the source electrode of triode NM6 and triode NM7, and is made
For voltage input negative terminal mouth 103.
The drain electrode of power MOS pipe NM4 connects with the drain electrode of detection metal-oxide-semiconductor NM5 and the positive voltage terminal mouth of operational amplifier OPA
It connects, and as the positive port 105 of voltage input.
The grid of triode NM7 is connect with the output port of the grid of triode NM6 and operational amplifier OPA.
The drain electrode of triode NM6 is connect with the positive input VP of the source electrode of triode NM7 and operational amplifier OPA.
Sampling mirror current source output port 104 of the drain electrode of triode NM7 as current ratio inductor.
Current comparator 302 includes: metal-oxide-semiconductor PM3, metal-oxide-semiconductor PM4, metal-oxide-semiconductor NM9 and load resistance R2.The leakage of metal-oxide-semiconductor PM4
Pole is connect with the grid of metal-oxide-semiconductor NM9, and the current input terminal mouth 106 as current comparator；The drain electrode and load of metal-oxide-semiconductor NM9
The second port of resistance R2 connects, and the comparison result output port 109 as current comparator；The grid of metal-oxide-semiconductor PM3 with
The drain electrode of metal-oxide-semiconductor PM3 connects, and as threshold current input port 107；The source electrode of metal-oxide-semiconductor PM3 and the source electrode of metal-oxide-semiconductor PM4 and
The first port of load resistance R2 connects, and as the positive port 110 of input voltage；The source electrode of metal-oxide-semiconductor NM9 is negative as input voltage
Port 108.
The voltage high-side current sampling comparator of embodiment 2 samples ratio with the voltage low-side current of embodiment 1 in principle
It is the same, and port having the same compared with device, only because the difference of current direction, according to common technical term, device
The title of part is different.For example, operational amplifier controls three in order to enable power MOS pipe is equal with the detection conduction voltage drop of metal-oxide-semiconductor
Pole pipe NM6 extracts follow current, the negative injection before being equivalent to.So electric current of triode NM7 scaled mirror triode NM6,
What is formed is that an electric current from triode NM7 drain electrode to power ground leaks, and the electric current of electric current leakage is as the defeated of current comparator
Enter signal, the corresponding load end of operational amplifier is current source, it is flowed through the control of metal-oxide-semiconductor PM3 by metal-oxide-semiconductor PM4 mirror image
Electric current is formed.When the electric current for flowing through power MOS pipe NM4 to be sampled is bigger than normal, triode NM7 allow by electric current be greater than
The electric current that metal-oxide-semiconductor PM4 is provided, then the grid voltage of common-source amplifier metal-oxide-semiconductor NM9 reduces, comparison result output port 109 becomes
For low level, so that low level indicates that power MOS pipe NM4 electric current is bigger than normal.
The application implementation circuit that the present invention is sampled in voltage high-side current, just can be used for the electric current of the power MOS pipe of P-channel
In sampling, as shown in Figure 9.Shown in Figure 10, power MOS pipe becomes P-channel MOS by N-channel MOS pipe NM4 on circuit structure
Pipe PM5 detects metal-oxide-semiconductor by N-channel MOS pipe NM5 and becomes P-channel metal-oxide-semiconductor PM6, the negative input mouth VN of operational amplifier
There is a circle to indicate that operational amplifier carries out current sample when low level effectively inputs.Because P-channel metal-oxide-semiconductor opens threshold
Threshold voltage is negative value, so the significant level of control driving signal Drive_L is low level, i.e., power MOS when it is low-voltage
Pipe and detection metal-oxide-semiconductor conducting, and operational amplifier carries out current sample.The circuit and function of other parts are identical, tools
Body running principle repeats no more.
In conjunction with the embodiments 1 and embodiment 2, it is same type on same chip with power MOS pipe that the present invention, which detects metal-oxide-semiconductor to be,
Various sizes of insulated gate transistor, in power MOS pipe conducting, detection metal-oxide-semiconductor is also conducting, and they are in identical electricity
It presses and is connected under the grid source driving voltage of size.When power MOS pipe is connected, produced in power MOS pipe conducting internal resistance to induced current
Raw conducting voltage, the conducting voltage are copied to by operational amplifier in the conducting resistance of detection metal-oxide-semiconductor, and follow current is generated.
Follow current refers to, operational amplifier is in order to make to detect the conducting voltage of metal-oxide-semiconductor and the conducting voltage of power MOS pipe
It is equal, it is necessary to the conducting resistance that certain electric current flows through detection metal-oxide-semiconductor to be injected or extract, when could make two metal-oxide-semiconductor conductings
Pressure drop it is equal, inject or the electric current that extracts be follow current.Since two metal-oxide-semiconductors are same type of N on same chip
Channel transistor, and be connected under identical driving voltage, thus resistivity having the same, then flowing through detection metal-oxide-semiconductor
Follow current be to flow through power MOS pipe be to induced current it is proportional, proportionality coefficient is their dimension scale system
Number.
Current comparator is using the follow current mirror current source of current ratio inductor output as input stage, and with one
Controllable current leakage or current source form first order trans-impedance amplifier as load.The output voltage of trans-impedance amplifier is using altogether
Source or the amplification of the second level of common emitter amplifier or Schmidt's shaping, can accurately compare the electric current of mirror current source and electric current leakage
Size.
Controllable current leakage refers to that the size of current of electric current leakage can control, and changes with the variation of control signal,
But the size of current of electric current leakage is constant when controlling signal stabilization.
Compared with traditional sampling technique, the advantages of present invention has both other current samples:
Firstly, signal source of the voltage that is generated in the internal resistance of power MOS pipe of electric current to be sampled as sampling, because being not required to
It wants series resistance or mutual inductor and causes the increase of extra resistance, therefore have the advantages that the high-efficient of lossless sampling；Secondly, with
The mode of differential amplification resistance sampling voltage is compared, the internal resistance of power MOS pipe much larger than concatenated sampling resistor resistance value, from
And in comparison the conduction voltage drop of power MOS pipe is biggish, then noise is relatively high, in addition sampling of the invention is in inner core
It is realized inside piece, common-mode noise is eliminated by difference sampling；Again, acted on by the voltage follow of operational amplifier, with
The low current proportional to power MOS pipe electric current is generated on the identical device of power MOS pipe, i.e., it is real in the way of voltage operational
The similar function of magnetic coupling mode of existing current transformer, thus the size and temperature of the size of electric current and power MOS pipe internal resistance
Coefficient is unrelated, effectively improves the precision of current sample；Finally, the electric current sampled directly passes through current comparator and current threshold
Compare, small power consumption, speed are fast, circuit is simple and area is small.
So the present invention may be implemented size be pacify times rank power current sampling, and and size in microampere rank
Bias current leakage electric current be compared.When the electric current of follow current mirror current source is greater than the electric current of controllable current leakage,
First trans-impedance amplifier exports higher voltage, which amplifies using second level amplifier, and output indicates sampling mirror image electricity
Stream is greater than the logic level of controllable current leakage current, switch-off power metal-oxide-semiconductor under the action of this logic level, and control passes through power
The size of current of metal-oxide-semiconductor.As long as being put in this way, the signal voltage of reflection switch power source output voltage is carried out error with reference voltage
The big size of current for changing controllable current leakage later, so that it may the size of current of metal-oxide-semiconductor is adjusted, in other words the accounting of Switching Power Supply,
Finally make the output voltage stabilization of Switching Power Supply in setting value.
Therefore, in view of the technology of existing current sample, self shortcoming is also apparent while keeping respective advantage,
The invention proposes a kind of new sample modes, learn from other's strong points to offset one's weaknesses, take into account sampling efficiency, the quality of sampled signal and precision, cost,
Efficient sampling efficiency, high sampling quality and inexpensive beneficial effect are obtained simultaneously.
It should also be appreciated by one skilled in the art that various illustrative logical boxs, mould in conjunction with the embodiments herein description
Electronic hardware, computer software or combinations thereof may be implemented into block, circuit and algorithm steps.In order to clearly demonstrate hardware and
Interchangeability between software surrounds its function to various illustrative components, frame, module, circuit and step above and carries out
It is generally described.Hardware is implemented as this function and is also implemented as software, depends on specific application and to entire
The design constraint that system is applied.Those skilled in the art can be directed to each specific application, be realized in a manner of flexible
Described function, still, this realization decision should not be construed as a departure from the scope of protection of this disclosure.
Claims (9)
1. a kind of current sample comparator circuit characterized by comprising incude for sampling to faradic current ratio
Device；The current ratio inductor includes: power MOS pipe, detection metal-oxide-semiconductor, operational amplifier and follow current mirror image pipe；
Conducting voltage is generated in power MOS pipe conducting internal resistance to induced current, which is put by the operation
Big device copies in the conducting resistance of the detection metal-oxide-semiconductor, generates follow current, described in the follow current mirror image pipe mirror image with
One and the follow current mirror current source proportional to induced current are generated with electric current.
2. a kind of current sample comparator circuit according to claim 1, which is characterized in that the current ratio inductor
It include: power current input port, control port, the positive port of voltage input, voltage input negative terminal mouth and sampling mirror current source
Output port；The positive port of the voltage input and voltage input negative terminal mouth are connect with positive pole and power cathode respectively, power
Current input terminal mouth and control port connect with the electric current to be detected and control signal provided outside current ratio inductor respectively
It connects.
3. a kind of current sample comparator circuit according to claim 2, which is characterized in that further include: being used for will be described
The follow current mirror current source of current ratio inductor output is compared with current threshold and exports the electric current of judging result
Comparator；The current input terminal of sampling the mirror current source output port and the current comparator of the current ratio inductor
Mouth connection.
4. a kind of current sample comparator circuit according to claim 3, which is characterized in that the current comparator packet
Include: current input terminal mouth, threshold current input port, the positive port of input voltage, input voltage negative terminal mouth and for export judgement
As a result comparison result output port；Threshold current signal outside threshold current input port and current comparator is connected, defeated
Enter positive voltage terminal mouth and input voltage negative terminal mouth is connect with positive pole and power cathode respectively.
5. a kind of current sample comparator circuit according to claim 4, which is characterized in that the follow current mirror image pipe
It include: triode PM1 and triode PM2；The drain electrode of the power MOS pipe connects with the reverse input end mouth of the operational amplifier
It connects；The grid of the power MOS pipe is connect with the enable port of the grid of the detection metal-oxide-semiconductor and the operational amplifier；Institute
The positive input mouth for stating operational amplifier is connect with the drain electrode of triode PM1 and the drain electrode of detection metal-oxide-semiconductor；The operation amplifier
The output port of device is connect with the grid of the grid of triode PM1 and triode PM2；The positive voltage terminal mouth of the operational amplifier
It is connect with the source electrode of the source electrode of triode PM1 and triode PM2；The voltage negative port of the operational amplifier and the power
The source electrode connection of the source electrode of metal-oxide-semiconductor and the detection metal-oxide-semiconductor；The drain electrode of triode PM2 is as the current ratio inductor
Sample mirror current source output port.
6. a kind of current sample comparator circuit according to claim 5, which is characterized in that the current comparator packet
It includes: electric current leakage and Schmidt；The input port of the electric current leakage is connect with the input port of the Schmidt, and as the electricity
Flow the current input terminal mouth of comparator；The output port of the electric current leakage is connect with Schmidt's voltage input negative terminal mouth；It is described to apply
Comparison result output port of the output port of Mi Te as the current comparator.
7. a kind of current sample comparator circuit according to claim 5, which is characterized in that the current comparator packet
It includes: electric current leakage, metal-oxide-semiconductor NM8 and load resistance R1；The input port of the electric current leakage is connect with the grid of metal-oxide-semiconductor NM8, and is made
For the current input terminal mouth of the current comparator；The output port of the electric current leakage is connect with the source electrode of metal-oxide-semiconductor NM8；Metal-oxide-semiconductor
The drain electrode of NM8 is connect with load resistance R1 and the comparison result output port as the current comparator.
8. a kind of current sample comparator circuit according to claim 4, which is characterized in that the follow current mirror image pipe
It include: triode NM6 and triode NM7；The grid and the amplifier of the grid of the power MOS pipe and the detection metal-oxide-semiconductor
The enable port of amplifier connects；The drain electrode of the power MOS pipe is connect with the reverse input end of the operational amplifier；It is described
The voltage negative port of operational amplifier is connect with the source electrode of the source electrode of triode NM6 and triode NM7；The power MOS pipe
It drains and is connect with the positive voltage terminal mouth of the drain electrode of the detection metal-oxide-semiconductor and the operational amplifier；The grid of triode NM7 and three
The connection of the output port of the grid of pole pipe NM6 and the operational amplifier；The drain electrode of triode NM6 and the source electrode of triode NM7
And the positive input connection of the operational amplifier；Sampling of the drain electrode of triode NM7 as the current ratio inductor
Mirror current source output port.
9. a kind of current sample comparator circuit according to claim 8, which is characterized in that the current comparator packet
It includes: metal-oxide-semiconductor PM3, metal-oxide-semiconductor PM4, metal-oxide-semiconductor NM9 and load resistance R2；The drain electrode of metal-oxide-semiconductor PM4 is connect with the grid of metal-oxide-semiconductor NM9,
And the current input terminal mouth as the current comparator；The drain electrode of metal-oxide-semiconductor NM9 is connect with the second port of load resistance R2,
And the comparison result output port as the current comparator；The grid of metal-oxide-semiconductor PM3 is connect with the drain electrode of metal-oxide-semiconductor PM3；MOS
The source electrode of pipe PM3 is connect with the first port of the source electrode of metal-oxide-semiconductor PM4 and load resistance R2.
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| CN201910596562.XA CN110350767A (en) | 2019-07-03 | 2019-07-03 | A kind of current sample comparator circuit |
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| CN201910596562.XA CN110350767A (en) | 2019-07-03 | 2019-07-03 | A kind of current sample comparator circuit |
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| CN111654305A (en) * | 2020-06-08 | 2020-09-11 | 郑州工业应用技术学院 | A computer network communication transmission system |
| CN112073052A (en) * | 2020-09-11 | 2020-12-11 | 浙江源创建筑智能科技有限公司 | Self-adaptive sampling interface circuit |
| CN112213553A (en) * | 2020-10-29 | 2021-01-12 | 国网河北省电力有限公司 | A device for measuring current |
| CN113258771A (en) * | 2021-07-15 | 2021-08-13 | 上海芯龙半导体技术股份有限公司南京分公司 | Control circuit and power supply chip |
| CN113866484A (en) * | 2021-10-20 | 2021-12-31 | 南京微盟电子有限公司 | Power tube circuit integrated with sampling resistor |
| CN118112307A (en) * | 2024-04-17 | 2024-05-31 | 杭州元芯半导体科技有限公司 | Current sampling circuit and current sampling method of switching power supply |
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