CN208079026U - low noise linear Hall sensor reading circuit - Google Patents
low noise linear Hall sensor reading circuit Download PDFInfo
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- CN208079026U CN208079026U CN201820625328.6U CN201820625328U CN208079026U CN 208079026 U CN208079026 U CN 208079026U CN 201820625328 U CN201820625328 U CN 201820625328U CN 208079026 U CN208079026 U CN 208079026U
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Abstract
The utility model is related to a kind of low noise linear hall sensor reading circuits.Including Hall element, rotatory current circuit, the first amplifier, chopper, the second amplifier, PTAT current generation circuit, switched capacitor notch filter, buffer；Hall element is connected with rotatory current circuit, the output end of rotatory current circuit is connect with the input terminal of the first amplifier, the output end of first amplifier is connected to the input terminal of chopper, the output end of chopper is connect with the input terminal of the second amplifier, the output end of second amplifier is connected with the input terminal of switched capacitor notch filter, the output end of switched capacitor notch filter is connected with the input terminal of buffer, and PTAT current generation circuit is connect with the input terminal of the second amplifier；Output end of the output end of buffer as low noise linear hall sensor reading circuit.The utility model can also reduce circuit ripple amplitude while can effectively eliminating circuit offset voltage and 1/f noise, to improve integrated circuit precision.
Description
Technical field
The utility model is related to a kind of low noise linear hall sensor reading circuits.
Background technology
In recent years, the Hall sensor based on CMOS technology possess low cost, low-power consumption, high reliability, high integration with
And many merits such as strong anti-interference ability, and Hall sensor can measure pressure, speed, acceleration by a series of conversions
The non-electrical amount such as degree, angular speed, electric current so that Hall sensor automotive field, smart home, industrial production, power management,
Space flight and military equal fields are widely used.However, for linear hall sensor, if high-precision applied to requiring
Automobile and industrial circle, and can steadily work in large temperature range, then the performance of linear hall sensor is proposed
Higher requirement needs Hall sensor to have better temperature characterisitic and precision, while meeting low noise voice output.
The Hall voltage signal generated using the Hall sensor that CMOS technology makes is very faint, generally in hundreds of microvolts
To between several millivolts, and it is contaminated with offset voltage and noise.Due to encapsulation stress generate piezoresistive effect and different materials it
Between Seebeck effect all Hall element can be made to generate larger offset voltage；Additionally due to the defect of CMOS technology leads to Hall
The thickness of element N traps is simultaneously uneven, so Hall element arm resistance is not consistent, to generate offset voltage；It reads simultaneously
Circuit can also introduce series of noise, such as thermal noise, flicker noise.For faint hall signal, these unreasonablys
Think that the garbage signal that factor generates can mask hall signal, it is therefore desirable to which high-precision reading circuit carrys out Linear Amplifer, and this is micro-
Weak signal eliminates offset voltage and 1/f noise simultaneously.High-precision instrument amplifier is exactly a relatively good selection, is compared
In traditional amplifier, the features such as high-precision meter amplifier shows low noise, low imbalance and high cmrr, and can
System accuracy is improved to be improved by corresponding structure.Other than required precision, the good temperature characterisitic of Hall sensor
It is also very crucial in many application fields.Change due to the Hall voltage meeting variation with temperature that Hall element generates, to lead
Total system precision is caused to be deteriorated, it is therefore desirable to carry out temperature-compensating to reduce temperature drift, Hall sensor can be made in larger temperature
It can accurately and steadily work in degree range.
The utility model proposes a kind of low noise, high-precision, the linear hall sensor reading circuit of Low Drift Temperature uses
Rotatory current technology and wave chopping technology can effectively eliminate circuit offset voltage and 1/f noise.Insertion switch capacitance is fallen into simultaneously
Wave filter（SC Notch Filter）Circuit ripple is effectively reduced, and entirety is improved using PTAT current compensation technique
Circuit temperature characteristic, to improve circuit precision.
Invention content
The purpose of this utility model is to provide a kind of low noise linear hall sensor reading circuits, can effectively disappear
Circuit ripple amplitude can also be reduced while except circuit offset voltage and 1/f noise, to improve integrated circuit precision；This practicality
It is novel to have huge application in the reading circuit field of Hall sensor.
To achieve the above object, the technical solution of the utility model is：A kind of low noise linear hall sensor reading electricity
Road, including Hall element, rotatory current circuit, the first amplifier, chopper, the second amplifier, PTAT current generation circuit, open
Close capacitor notch filter, buffer；The Hall element is connected with the input terminal of rotatory current circuit, rotatory current circuit
Output end is connect with the input terminal of the first amplifier, and the output end of the first amplifier is connected to the input terminal of chopper, chopper
Output end connect with the input terminal of the second amplifier, the output end of the second amplifier and the input of switched capacitor notch filter
End be connected, the output end of switched capacitor notch filter is connected with the input terminal of buffer, the PTAT current generation circuit and
The input terminal of second amplifier connects；The output end of buffer is defeated as the low noise linear hall sensor reading circuit
Outlet.
In one embodiment of the utility model, input terminal that the output end of the chopper passes through resistance and the second amplifier
Connection.
In one embodiment of the utility model, the output end of the switched capacitor notch filter passes through resistance and buffer
Input terminal connection.
In one embodiment of the utility model, the Hall element is that there are four the Hall discs of port for tool；The electric rotating
Current circuit includes the first to the 8th metal-oxide-semiconductor, and connection relation is as follows：One end of first metal-oxide-semiconductor, one end of the second metal-oxide-semiconductor are connected
It is connected to the first port of Hall disc, the other end of the first metal-oxide-semiconductor is connected with one end of the second metal-oxide-semiconductor is connected to power end, the 2nd MOS
The first output end that the other end of pipe is connected with one end of the 4th metal-oxide-semiconductor as the rotatory current circuit, third metal-oxide-semiconductor
The other end is connected with the other end of the 4th metal-oxide-semiconductor is connected to the second port of Hall disc, one end and the 6th metal-oxide-semiconductor of the 5th metal-oxide-semiconductor
One end be connected and be connected to the third port of Hall disc, the other end of the 5th metal-oxide-semiconductor is connected with one end of the 7th metal-oxide-semiconductor is connected to GND,
The second output terminal that the other end of 6th metal-oxide-semiconductor is connected with one end of the 8th metal-oxide-semiconductor as the rotatory current circuit, the 7th
The other end of metal-oxide-semiconductor is connected with the other end of the 8th metal-oxide-semiconductor is connected to the 4th port of Hall disc.
In one embodiment of the utility model, first metal-oxide-semiconductor, the 4th metal-oxide-semiconductor, the 6th metal-oxide-semiconductor, the 7th metal-oxide-semiconductor
Control terminal is connected, and as the first control terminal of the rotatory current circuit, second metal-oxide-semiconductor, third metal-oxide-semiconductor, the 5th
Metal-oxide-semiconductor, the 8th metal-oxide-semiconductor control terminal be connected, and as the second control terminal of the rotatory current circuit, the first control terminal
Control signal, the control signal of the second control terminal is provided by the non-overlapping clock of two-phase.
In one embodiment of the utility model, the switched capacitor notch filter include the first to the 8th switching tube group,
First capacitance, the second capacitance, the described first to the 8th switching tube group include two metal-oxide-semiconductors, the source electrode of one metal-oxide-semiconductor with it is another
The drain electrode of metal-oxide-semiconductor is connected to the first end of the switching tube group, and the drain electrode of one metal-oxide-semiconductor is connect with the source electrode of another metal-oxide-semiconductor
As the second end of the switching tube group, the grid of one metal-oxide-semiconductor and the grid of another metal-oxide-semiconductor are provided by the clock being completely reversed
Control signal；The first end of first switch pipe group is connected with the second end of the 5th metal-oxide-semiconductor group as the switched capacitor notch
The second end of the first input end of filter, first switch pipe group is connected with the second end of second switch pipe group, and through first
Capacitance is connect with the second end of third switching tube group, the second end of the 6th switching tube group, the first end of second switch pipe group and the
The second end of four switching tube groups is connected the first output end as the switched capacitor notch filter, third switching tube group
The second input terminal that first end is connected with the second end of the 7th switching tube group as the switched capacitor notch filter, the 4th
The first end of switching tube group is connected with the first end of the 5th switching tube group, and through the first of the second capacitance and the 7th switching tube group
The first end connection at end, the 8th switching tube group, the first end of the 6th switching tube group are connected with the second end of the 8th switching tube group
Second output terminal as the switched capacitor notch filter.
In one embodiment of the utility model, the PTAT current generation circuit includes PTAT current generative circuit and temperature
Spend unrelated current generating circuit, wherein PTAT current generative circuit is connect with the positive input terminal of second amplifier, with temperature
Unrelated current generating circuit is spent to connect with the negative input end of second amplifier.
In one embodiment of the utility model, the PTAT current generative circuit includes metal-oxide-semiconductor M1, M2, M3, triode
Q1, Q2, resistance R5, the grid of amplifier A4, M1, the grid of M2, M3 grid be connected and be connected to the output end of A4, the source electrode of M1,
The source electrode of M2, the source electrode of M3, which are connected, is connected to power end, and the drain electrode of M1 is connect with the negative input end of the emitter of Q1, A4, the leakage of M2
The positive input terminal of pole and one end of R5, A4 connects, and the drain electrode of M3 is connected to the positive input terminal of second amplifier, and R5's is another
End is connect with the emitter of Q2, the base stage of Q1 and the collector of Q1, the base stage of Q2, Q2 collector be connected and be connected to GND.
In one embodiment of the utility model, the temperature independent current generating circuit includes metal-oxide-semiconductor M4, M5, M6,
Triode Q3, Q4, resistance R6, R7, R8, R9, amplifier A5, A6, the grid of M4 and the output end of A6 connect, the drain electrode of M4 and M5
Drain electrode, the grid of M5, M6 grid connection, the negative input end of the source electrode of M4 and one end of R9, A6 connects, source electrode, the M6 of M5
Source electrode be connected be connected to power end, the drain electrode of M6 is connected to the negative input end of second amplifier, the base stage of Q3 and the collection of Q3
Electrode, the base stage of Q4, the collector of Q4, R9 the other end be connected be connected to GND, the emitter of Q3 is connected with one end of R7 is connected to A5
Positive input terminal, the negative input end connection of the emitter of Q4 through one end of R6 and R8, A5, the other end of R7, the other end phase of R8
It is connected to the positive input terminal of A6, the output end of A5.
Compared to the prior art, the utility model has the advantages that：The hall sensing proposed in the utility model
The reading circuit of device can also reduce circuit ripple amplitude while can effectively eliminating circuit offset voltage and 1/f noise, from
And improve integrated circuit precision；The utility model has huge application in the reading circuit field of Hall sensor.
Description of the drawings
Fig. 1 is traditional band copped wave instrument amplifier structure chart.
Fig. 2 is linear hall sensor reading circuit system construction drawing.
Fig. 3 is rotatory current circuit diagram.
Fig. 4 is rotatory current circuit output voltage schematic diagram.
Fig. 5 is switched capacitor notch filter structure chart.
Fig. 6 is switched capacitor notch filter fundamental diagram.
Fig. 7 is PTAT current generative circuit schematic diagram.
Fig. 8 is temperature independent current generating circuit schematic diagram.
Specific implementation mode
Below in conjunction with the accompanying drawings, the technical solution of the utility model is specifically described.
A kind of low noise linear hall sensor reading circuit of the utility model, including Hall element, electric rotating galvanic electricity
Road, the first amplifier, chopper, the second amplifier, PTAT current generation circuit, switched capacitor notch filter, buffer；Institute
It states Hall element with the input terminal of rotatory current circuit to be connected, the input terminal of the output end of rotatory current circuit and the first amplifier
Connection, the output end of the first amplifier are connected to the input terminal of chopper, the input of the output end of chopper and the second amplifier
End connection, the output end of the second amplifier are connected with the input terminal of switched capacitor notch filter, switched capacitor notch filter
Output end be connected with the input terminal of buffer, the PTAT current generation circuit is connect with the input terminal of the second amplifier；It is slow
Rush output end of the output end of device as the low noise linear hall sensor reading circuit.The output end of the chopper is logical
Resistance is crossed to connect with the input terminal of the second amplifier.The output end of the switched capacitor notch filter passes through resistance and buffer
Input terminal connection.
The Hall element is that there are four the Hall discs of port for tool；The rotatory current circuit includes the first to the 8th MOS
Pipe, connection relation are as follows：One end of first metal-oxide-semiconductor, the second metal-oxide-semiconductor one end be connected and be connected to the first port of Hall disc, the
The other end of one metal-oxide-semiconductor is connected with one end of the second metal-oxide-semiconductor is connected to power end, the other end of the second metal-oxide-semiconductor and the 4th metal-oxide-semiconductor
One end is connected the first output end as the rotatory current circuit, and the other end of third metal-oxide-semiconductor is another with the 4th metal-oxide-semiconductor
End, which is connected, is connected to the second port of Hall disc, and one end of the 5th metal-oxide-semiconductor is connected with one end of the 6th metal-oxide-semiconductor is connected to the of Hall disc
Three ports, the other end of the 5th metal-oxide-semiconductor is connected with one end of the 7th metal-oxide-semiconductor is connected to GND, the other end and the 8th of the 6th metal-oxide-semiconductor
One end of metal-oxide-semiconductor is connected the second output terminal as the rotatory current circuit, the other end and the 8th MOS of the 7th metal-oxide-semiconductor
The other end of pipe, which is connected, is connected to the 4th port of Hall disc.First metal-oxide-semiconductor, the 4th metal-oxide-semiconductor, the 6th metal-oxide-semiconductor, the 7th MOS
The control terminal of pipe is connected, and as the first control terminal of the rotatory current circuit, second metal-oxide-semiconductor, third metal-oxide-semiconductor,
5th metal-oxide-semiconductor, the 8th metal-oxide-semiconductor control terminal be connected, and as the second control terminal of the rotatory current circuit, the first control
The control signal at end, the control signal of the second control terminal are provided by the non-overlapping clock of two-phase.
The switched capacitor notch filter includes the first to the 8th switching tube group, the first capacitance, the second capacitance, and described the
One to the 8th switching tube group includes two metal-oxide-semiconductors, and the drain electrode of the source electrode of one metal-oxide-semiconductor and another metal-oxide-semiconductor is connected to described
The first end of switching tube group, the drain electrode of one metal-oxide-semiconductor and the source electrode of another metal-oxide-semiconductor are connected to the second of the switching tube group
End, the grid of one metal-oxide-semiconductor and the grid of another metal-oxide-semiconductor provide control signal by the clock being completely reversed；First switch pipe group
The first input end that is connected as the switched capacitor notch filter with the second end of the 5th metal-oxide-semiconductor group of first end,
The second end of one switching tube group is connected with the second end of second switch pipe group, and the through the first capacitance and third switching tube group
The second end connection at two ends, the 6th switching tube group, the first end of second switch pipe group are connected with the second end of the 4th switching tube group
Connect the first output end as the switched capacitor notch filter, first end and the 7th switching tube group of third switching tube group
Second end is connected the second input terminal as the switched capacitor notch filter, the first end and the 5th of the 4th switching tube group
The first end of switching tube group is connected, and the first of the first end through the second capacitance and the 7th switching tube group, the 8th switching tube group
End connection, the first end of the 6th switching tube group is connected with the second end of the 8th switching tube group filters as the switched capacitor notch
The second output terminal of wave device.
The PTAT current generation circuit includes PTAT current generative circuit, temperature independent current generating circuit,
In, PTAT current generative circuit is connect with the positive input terminal of second amplifier, temperature independent current generating circuit with
The negative input end of second amplifier connects.The PTAT current generative circuit includes metal-oxide-semiconductor M1, M2, M3, triode Q1,
Q2, resistance R5, the grid of amplifier A4, M1, the grid of M2, M3 grid be connected and be connected to the output end of A4, the source electrode of M1, M2
Source electrode, M3 source electrode be connected be connected to power end, the drain electrode of M1 is connect with the negative input end of the emitter of Q1, A4, the drain electrode of M2 and
The positive input terminal connection of one end of R5, A4, the drain electrode of M3 are connected to the positive input terminal of second amplifier, the other end of R5 and
The emitter of Q2 connects, the base stage of Q1 and the collector of Q1, the base stage of Q2, Q2 collector be connected and be connected to GND.Described and temperature
Unrelated current generating circuit includes metal-oxide-semiconductor M4, M5, M6, triode Q3, Q4, resistance R6, R7, R8, R9, amplifier A5, A6,
The output end of the grid of M4 and A6 connect, and the drain electrode of M4 is connect with the grid of the drain electrode of M5, the grid of M5, M6, the source electrode of M4 and
The negative input end connection of one end of R9, A6, the source electrode of M5, the source electrode of M6, which are connected, is connected to power end, and the drain electrode of M6 is connected to described
The negative input end of second amplifier, the base stage of Q3 are connected with the other end of the collector of Q3, the base stage of Q4, the collector of Q4, R9
It is connected to GND, the emitter of Q3 is connected with one end of R7 is connected to the positive input terminal of A5, and the emitter of Q4 is through one end of R6 and R8, A5
Negative input end connection, the other end of R7, the other end of R8, which are connected, is connected to the output end of the positive input terminal of A6, A5.
It is the specific implementation process of the utility model below.
The utility model design is mainly by front end Hall element, rotatory current circuit, amplifier A1, chopper CH1, amplification
Device A2, SC Notch Filter, PTAT current generation circuit and buffer A3 compositions.The utility model is based on rotatory current
Technology and wave chopping technology are studied and are devised a kind of applied to linear hall sensor in combination with PTAT current compensation technique
High-precision, low noise, Low Drift Temperature reading circuit.Traditional band copped wave instrument applied to Hall sensor reading circuit is amplified
Device structure is as shown in Figure 1.The design uses two-phase rotatory current technology on the basis of traditional structure, realizes Hall voltage
With the separation of Hall offset voltage, offset voltage and 1/f are eliminated in combination with wave chopping technology and introducing SC Notch Filter
Noise, and output ripple amplitude can be effectively inhibited, to substantially increase the precision of integrated circuit.It is mended using PTAT current
Technology is repaid to improve circuit temperature characteristic, reduces temperature drift, keeps Hall sensor accurate in -40 DEG C to 150 DEG C temperature ranges
Steadily work.The utility model design is using 0.18 μm of CMOS technology realization of SMIC, supply voltage 3.6V, chopping frequency
fchopFor 250kHz, emulated by Spectre, integrated circuit-three dB bandwidth is 11kHz, Ripple Suppression ratio up to 39.6dB, etc.
Effect input reference noise power spectral density PSD is 15nV/ √ Hz, quiescent output voltage 1.8V, integrated circuit can be in temperature-
The simulation result of stable and accurate work within the scope of 40 DEG C to 150 DEG C, global design has reached low noise, high-precision and high stable
Property Hall sensor reading circuit requirement.
The structure chart of total system is as shown in Figure 2.Hall element is directly connected directly with rotatory current circuit, rotatory current
Circuit output end is connected with the first order amplifier A1 in the access, and the output end of amplifier A1 is directly connected to chopper CH1, copped wave
The output end of device CH1 is connected by resistance R1 with the second level amplifier A2 in the access, amplifier A2 output ends and SC Notch
Filter is connected, and the output end of SC Notch Filter is connected by resistance R3 with the buffer A3 in the access.Meanwhile
PTAT current compensation circuit is directly connected to the input terminal of A2.Hall element generates corresponding Hall by bias current outside piece
Voltage can make Hall element generate very serious offset voltage and low frequency 1/f noise due to defective workmanship etc., thus by
The signal that Hall element generates is by Hall voltage VHallWith offset voltage VoffsetAnd 1/f noise composition.It is generated by Hall element
Signal, after two-phase rotatory current circuit, Hall voltage VHallIt is f to be modulated into frequencyspinAC signal output, and
Offset voltage VoffsetIt is maintained at DC state with low frequency 1/f noise.It is amplified by first order amplifier A1, using copped wave
Frequency is fchopChopper CH1, the Hall voltage of exchange is demodulated to direct current signal, and Hall element and amplifier itself
Offset voltage VoffsetIt is f to be then modulated into frequency with low frequency 1/f noisechopAC signal, chopper CH1 output ends with
Ripple form exports.In order to ensure accurately to demodulate Hall voltage, fspinWith fchopIt is arranged to identical frequency.The ripple by by R1,
The first-order low-pass wave effect of R2, C1 and A2 composition is filtered out, and remnants ripple is further f by frequencyspinSC Notch
Filter is eliminated, so as to be effectively reduced output ripple amplitude.Finally utilize buffer A2 is bis- to turn single output one and magnetic
The directly proportional Hall voltage of field intensity.Since the Hall voltage that Hall element generates can decline as temperature increases, with temperature
It is negatively correlated, therefore in order to improve the linearity and temperature characterisitic of output Hall voltage, in the positive input terminal of second level amplifier A2
Inject a PTAT current I being positively correlated with absolute temperaturePTATA temperature independent electric current I is injected with negative input endnontemp
To carry out temperature-compensating.The pressure drop for being increased and being risen with temperature using one generated on resistance R2, to compensate with temperature liter
High and decline Hall voltage, to improve output Hall voltage temperature characterisitic and the linearity.
Front end Hall element generally use N-well process is made, including four ports, can be equivalent to a favour stone
Electric bridge.Due to the inhomogeneities of Hall element doping concentration and the difference of N well depths, Hall sensor can all generated very tight
Weight offset voltage and low frequency 1/f noise, and Hall sensor generate hall signal by instrument amplifier amplification when,
Also imbalance and the noise of some amplifiers can be superimposed.The magnitude of these non-ideal factors is very big, its magnitude arrives greatly in many cases
Mask the signal of Hall element output.Therefore, it is necessary to take the relevant technologies to eliminate imbalance and the noise of Hall sensor.Rotation
Turn current technique to be applied in Hall sensor as a kind of method of elimination dynamic imbalance, by changing Hall element control
The position with output end is held to change Hall voltage VHallWith offset voltage VoffsetPolarity, realize that Hall voltage and Hall lose
Adjust the separation of voltage.The circuit diagram of two-phase rotatory current technology is as shown in Figure 3.Wherein 1a, 1b, 1c, 1d are Hall element
Control port, 2a, 2b, 2c, 2d, 3a, 3b, 3c, 3d are MOS switch pipe.Its working principle is that：As CLK=1, CLK '=0（CLK
And the non-overlapping clock of two-phase of CLK ' MOS switch pipes in order to control）, switching tube 3a, 2b, 2d, 3d conducting, switching tube 3b, 2a, 2c,
3d is disconnected.1a connects supply voltage, 1c ground connection at this time, and electric current flows to 1c by 1a.1b meets VO+, 1d meets VO-, rotatory current circuit output
Voltage be VHall+Voffset.As CLK=0, CLK '=1, switching tube 3a, 2b, 2d, 3d are disconnected, and switching tube 3b, 2a, 2c, 3d are led
It is logical；1b connects supply voltage, 1d ground connection at this time, and electric current flows to 1d by 1b.1a meets VO+, 1c meets VO-, the electricity of rotatory current circuit output
Pressure is-VHall+Voffset.Hall element output signal realizes Hall voltage V after rotatory current processing of circuitHallWith imbalance
Voltage VoffsetSeparation, while Hall voltage VHallIt is f to be modulated onto frequencyspinAC signal, and offset voltage VoffsetIt protects
It holds in DC state, as shown in Figure 4.
In order to further eliminate circuit ripple, introduce SC Notch Filter circuits, as shown in figure 5, wherein CH and
CHB is one group and is completely reversed clock.In order to realize the sampling of continuous time signal, two sampling capacitance C2 and C3 have been used, two
Person alternately enters sampling, holding stage：When C2 samples input end signal, C3 keeps the signal sampled in a stage；
C3 enters the sampling period later, and C2 enters hold period.The operation principle of notch filter is as shown in fig. 6, notch filter
Switching frequency it is identical as chopping frequency, but 90 ° of phase delay, the sampling capacitance in such notch filter can be adopted
Sample to chopper CH1 output voltages median, that is, integrated circuit input voltage.The Ripple Suppression of notch filter
Multiple is directly related with the accuracy of clock, therefore, to assure that the clock of notch filter will have accurate 90 ° with chopper clock
Phase delay.
In order to improve the temperature characterisitic and the linearity of output Hall voltage, PTAT current compensation technique is introduced.PTAT electricity
Generative circuit is flowed as shown in fig. 7, temperature independent current generating circuit is as shown in Figure 8.PTAT current is one and absolutely temperature
Directly proportional electric current is spent, use is with VTOn the basis of bias source generate.Metal-oxide-semiconductor M1 is identical with M2, can make in this way
I1=I2=IPTAT.Triode Q1 and Q2 types are identical, and emitter area ratio is 1：N usually takes 1 in actual design：8.By transporting
The negative-feedback function of putting can obtain A points and B point voltages are equal, so taking the emitter area ratio of triode Q1 and Q2 herein
It is 1：8, then output current I1 is：
Due to VTIt is a relevant technological parameter of positive temperature coefficient, it is possible to obtain a PTAT current.Work as temperature
When variation, Hall disc will produce the voltage declined with temperature rise, so larger temperature drift is will produce, so needing temperature
Degree compensates to reduce temperature drift.Its working principle is that：As temperature rise △ T, Hall disc will produce the voltage △ V of a decline,
A PTAT current I with absolute temperature is proportional to is picked out using benchmarkPTAT, and access the positive input terminal of second level amplifier A2.
A simple band-gap reference is recycled to generate a temperature independent electric current Inontemp, and access the negative of second level amplifier A2
Input terminal, the pressure drop risen with temperature raising using one generated on resistance R2 are declined to compensate with temperature raising
Hall voltage, to improve the output Hall voltage temperature characterisitic and linearity.
It is the preferred embodiment of the utility model above, it is all to change according to made by technical solutions of the utility model, it is produced
Function without departing from technical solutions of the utility model range when, belong to the scope of protection of the utility model.
Claims (9)
1. a kind of low noise linear hall sensor reading circuit, which is characterized in that including Hall element, rotatory current circuit,
First amplifier, chopper, the second amplifier, PTAT current generation circuit, switched capacitor notch filter, buffer；It is described
Hall element is connected with the input terminal of rotatory current circuit, and the input terminal of the output end of rotatory current circuit and the first amplifier connects
It connects, the output end of the first amplifier is connected to the input terminal of chopper, the input terminal of the output end of chopper and the second amplifier
Connection, the output end of the second amplifier are connected with the input terminal of switched capacitor notch filter, switched capacitor notch filter
Output end is connected with the input terminal of buffer, and the PTAT current generation circuit is connect with the input terminal of the second amplifier；Buffering
Output end of the output end of device as the low noise linear hall sensor reading circuit.
2. low noise linear hall sensor reading circuit according to claim 1, which is characterized in that the chopper
Output end is connect by resistance with the input terminal of the second amplifier.
3. low noise linear hall sensor reading circuit according to claim 1, which is characterized in that the switching capacity
The output end of notch filter is connected by the input terminal of resistance and buffer.
4. low noise linear hall sensor reading circuit according to claim 1, which is characterized in that the Hall element
For the Hall disc for having there are four port；The rotatory current circuit includes the first to the 8th metal-oxide-semiconductor, and connection relation is as follows：The
One end of one metal-oxide-semiconductor, the second metal-oxide-semiconductor one end be connected and be connected to the first port of Hall disc, the other end of the first metal-oxide-semiconductor and second
One end of metal-oxide-semiconductor, which is connected, is connected to power end, and the other end of the second metal-oxide-semiconductor is connected with one end of the 4th metal-oxide-semiconductor as the rotation
Turn the first output end of current circuit, the other end of third metal-oxide-semiconductor is connected with the other end of the 4th metal-oxide-semiconductor is connected to the of Hall disc
Two-port netwerk, one end of the 5th metal-oxide-semiconductor is connected with one end of the 6th metal-oxide-semiconductor is connected to the third port of Hall disc, the 5th metal-oxide-semiconductor it is another
One end is connected with one end of the 7th metal-oxide-semiconductor is connected to GND, and the other end of the 6th metal-oxide-semiconductor is connected conduct with one end of the 8th metal-oxide-semiconductor
The second output terminal of the rotatory current circuit, the other end of the 7th metal-oxide-semiconductor is connected with the other end of the 8th metal-oxide-semiconductor is connected to Hall
4th port of disk.
5. low noise linear hall sensor reading circuit according to claim 4, which is characterized in that the first MOS
Pipe, the 4th metal-oxide-semiconductor, the 6th metal-oxide-semiconductor, the 7th metal-oxide-semiconductor control terminal be connected, and as the rotatory current circuit first control
End processed, second metal-oxide-semiconductor, third metal-oxide-semiconductor, the 5th metal-oxide-semiconductor, the 8th metal-oxide-semiconductor control terminal be connected, and as the rotation
Second control terminal of current circuit, when the control signal of the first control terminal, the control signal of the second control terminal are non-overlapping by two-phase
Clock provides.
6. low noise linear hall sensor reading circuit according to claim 1, which is characterized in that the switching capacity
Notch filter includes the first to the 8th switching tube group, the first capacitance, the second capacitance, and the described first to the 8th switching tube group is wrapped
Two metal-oxide-semiconductors are included, the drain electrode of the source electrode of one metal-oxide-semiconductor and another metal-oxide-semiconductor is connected to the first end of the switching tube group, one
Drain electrode and the source electrode of another metal-oxide-semiconductor of metal-oxide-semiconductor are connected to the second end of the switching tube group, the grid of one metal-oxide-semiconductor with it is another
The grid of one metal-oxide-semiconductor provides control signal by the clock being completely reversed；The first end of first switch pipe group and the 5th metal-oxide-semiconductor group
Second end is connected the first input end as the switched capacitor notch filter, the second end and second of first switch pipe group
The second end of switching tube group is connected, and the second of the second end through the first capacitance and third switching tube group, the 6th switching tube group
End connection, the first end of second switch pipe group is connected with the second end of the 4th switching tube group filters as the switched capacitor notch
The first end of first output end of wave device, third switching tube group is connected with the second end of the 7th switching tube group as the switch
Second input terminal of capacitor notch filter, the first end of the 4th switching tube group are connected with the first end of the 5th switching tube group,
And it is connect with the first end of the 7th switching tube group, the first end of the 8th switching tube group through the second capacitance, the of the 6th switching tube group
The second output terminal that one end is connected with the second end of the 8th switching tube group as the switched capacitor notch filter.
7. low noise linear hall sensor reading circuit according to claim 1, which is characterized in that the PTAT current
Generation circuit includes PTAT current generative circuit, temperature independent current generating circuit, wherein PTAT current generative circuit with
The positive input terminal of second amplifier connects, the negative input of temperature independent current generating circuit and second amplifier
End connection.
8. low noise linear hall sensor reading circuit according to claim 7, which is characterized in that the PTAT current
Generative circuit includes metal-oxide-semiconductor M1, M2, M3, triode Q1, Q2, resistance R5, the grid of amplifier A4, M1, the grid of M2, M3
Grid, which is connected, is connected to the output end of A4, the source electrode of M1, the source electrode of M2, M3 source electrode be connected and be connected to power end, the drain electrode of M1 and Q1
Emitter, A4 negative input end connection, the drain electrode of M2 connect with the positive input terminal of one end of R5, A4, and the drain electrode of M3 is connected to
The emitter of the positive input terminal of second amplifier, the other end of R5 and Q2 connect, the base stage of Q1 and the collector of Q1, Q2
Base stage, Q2 collector be connected be connected to GND.
9. low noise linear hall sensor reading circuit according to claim 7, which is characterized in that it is described with temperature without
The current generating circuit of pass includes metal-oxide-semiconductor M4, M5, M6, triode Q3, Q4, resistance R6, R7, R8, R9, amplifier A5, A6, M4
Grid and the output end of A6 connect, the drain electrode of M4 connect with the grid of the drain electrode of M5, the grid of M5, M6, the source electrode and R9 of M4
One end, A6 negative input end connection, the source electrode of M5, the source electrode of M6, which are connected, is connected to power end, and the drain electrode of M6 is connected to described the
The negative input end of two amplifiers, the base stage of Q3 are connected with the other end of the collector of Q3, the base stage of Q4, the collector of Q4, R9
To GND, the emitter of Q3 is connected with one end of R7 is connected to the positive input terminal of A5, and the emitter of Q4 is through one end of R6 and R8, A5
Negative input end connects, and the other end of R7, the other end of R8, which are connected, is connected to the output end of the positive input terminal of A6, A5.
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| CN201820625328.6U CN208079026U (en) | 2018-04-28 | 2018-04-28 | low noise linear Hall sensor reading circuit |
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