CN101886933A - Hall switch circuit with temperature compensation - Google Patents

Abstract

The invention relates to a Hall switch circuit with temperature compensation, comprising a voltage stabilizer, a Hall induction sheet, a Hall voltage difference amplifier, a hysteresis comparator and an output unit, wherein the Hall induction sheet is connected between the output and an earth wire of the voltage stabilizer; two input ends of the Hall voltage difference amplifier are respectively connected with the Hall induction sheet; the hysteresis comparator is connected with the output end of the Hall voltage difference amplifier; and the output unit is connected with the input end of the hysteresis comparator. The Hall switch circuit is characterized in that the Hall voltage difference amplifier comprises a difference input pair, a current source and a load resistor, wherein the difference input pair consists of two transistors; the current source offsets the difference input pair and is directly proportional to absolute temperature; and the load resistor is respectively in series connected with the transistors of the difference input pair and is made from materials the same as that of the Hall induction sheet. The Hall switch circuit can eliminate the influence of microhenry temperature coefficient without special requirement for a process and is well controlled.

Description

The Hall switch circuit of band temperature compensation

Technical field

The present invention relates to a kind of Hall switch circuit, particularly a kind of Hall switch circuit with temperature compensation.

Background technology

The principle of Hall effect is: to a suitable Hall material, if along the V that switches on its directions X _R, add magnetic field B on the Y direction, on the Z direction voltage V can appear then _H, V _HBe called Hall voltage, itself and magnetic field B, voltage V _RWith the pass of material self be

$V_H={\mathrm{\μ}}_H{\mathrm{BV}}_R\frac{W}{L}\mathrm{\σ}\left(\frac{L}{W}\right)---\left(1\right)$

L wherein, W are the length of this Hall material and wide,

Be the Geometric corrections factor, μ _HBe hall mobility.

Semiconductor is good Hall effect material, so semiconductor integrated hall effect sensor is widely used in the various electronic equipments.Hall switch is a kind of in the Hall element, and its principle is: utilize integrated semiconductor Hall plate induction external magnetic field, output Digital Logic 0 or 1.Its transport property as shown in Figure 1, when the external magnetic field greater than working point magnetic field intensity B _OPThe time, be output as 0; When the external magnetic field less than point of release magnetic field intensity B _RPThe time, be output as 1.

Conventional Hall switch circuit composition module comprises voltage stabilizer 201, hall sensing sheet 202, Hall voltage differential amplifier 203, hysteresis comparator 204 and output unit 205 as shown in Figure 2.

If the gain of Hall voltage differential amplifier is A _V, the sluggish width of hysteresis comparator is V _CO, then have

A _VV _H＝V _CO (2)

Do not consider symbol, obtain B by formula (1) and (2) _OPAnd B _RPThe expression formula unification be:

$B=\frac{V_{\mathrm{CO}}}{A_V{\mathrm{\μ}}_H{V}_R\frac{W}{L}\mathrm{\σ}\left(\frac{L}{W}\right)}---\left(3\right)$

μ in the formula (3) _HRising with temperature descends, and just negative temperature characteristic will make B _OPAnd B _RPExcellent temperature stability is arranged, must make in the formula (3) other parameter suitable temperature coefficient be arranged to offset μ _HNegative temperature coefficient.And

With

These two geometric parameter temperatures coefficient are very little, can ignore, so can only be to V _CO, A _VAnd V _RIn one or several carry out temperature compensation.

According to These characteristics, publication number is that the Chinese patent application of CN101290233A has been announced a kind of temperature compensation, A in the formula (3) _VAnd V _RUnder the condition to temperature constant, regulate V _COTemperature coefficient to reduce μ _HThe influence of temperature coefficient, finally reduce B _OPAnd B _RPTemperature coefficient.It is a certain particular value that its circuit realizes requiring the temperature coefficient of one type resistance, and this just requires arts demand that the resistance of specified temp coefficient value is provided, and is more special to the requirement of technology.

Publication number is that the used method of the Chinese patent application of CN101290233 is V in the formula (3) _CO, A _VUnder the condition of maintenance to temperature constant, regulate V _RTemperature coefficient to reduce μ _HThe influence of temperature coefficient, finally reduce B _OPAnd B _RPTemperature coefficient.Its circuit is realized obtaining the item of another positive temperature coefficient to reduce μ with the item addition of the item of a positive temperature coefficient (PTC) and a negative temperature coefficient _HThe influence of negative temperature characteristic.This method makes second-order characteristics difficult with control; Consider the drift of material behavior, the consistance after the batch process also is difficult to guarantee.

Summary of the invention

The technical problem to be solved in the present invention is the defective that will overcome prior art, provides a kind of and can eliminate μ _HThe influence of temperature coefficient, and technology there is not the yet Hall switch circuit of the band temperature compensation of fine control of specific (special) requirements.

A kind of Hall switch circuit of the present invention with temperature compensation, comprise voltage stabilizer, be connected the output of described voltage stabilizer and the hall sensing sheet between the ground wire, two Hall voltage differential amplifiers that input end links to each other with described hall sensing sheet respectively, the hysteresis comparator that links to each other with the output terminal of described Hall voltage differential amplifier, and the output unit that links to each other with the output terminal of described hysteresis comparator, it is characterized in that, described Hall voltage differential amplifier comprises that the difference input of being made up of two transistors is right, the described difference of setovering is imported the right current source that is proportional to absolute temperature, and is serially connected in the pull-up resistor that one and described hall sensing sheet on each right transistor of described difference input are made with material respectively.

The Hall switch circuit of the band temperature compensation that the present invention provides is by making V in the formula (3) _COAnd V _RMaintenance is accurately controlled the gain A of Hall voltage differential amplifier to temperature constant _VTemperature coefficient, make itself and μ _HThe temperature coefficient equal and opposite in direction, opposite in sign, the temperature coefficient of the two thereby cancel out each other obtains the B to temperature constant _OPAnd B _RPThe structure of this Hall voltage differential amplifier is: come the input of bias transistor difference right with the electric current that is proportional to absolute temperature, import right load with the resistance of hall sensing sheet material of the same type as difference.The mutual conductance of the Hall voltage differential amplifier of this structure has the characteristic to temperature constant, so, this Amplifier Gain A _VTemperature coefficient only relevant with the temperature characterisitic of the resistance of hall sensing sheet material of the same type, it just can follow the tracks of μ fully _HTemperature characterisitic (comprising second-order characteristics), produce desirable neutralization effect, and process drift is very little to consistance influence.

Description of drawings

Fig. 1 is a Hall switch transport property synoptic diagram.

Fig. 2 is conventional Hall switch circuit schematic diagram.

Fig. 3 is the schematic diagram of a preferred embodiment of Hall switch circuit of the present invention.

Fig. 4 a-c is the alternative preferred embodiment of the Hall voltage differential amplifier among Fig. 3.

Embodiment

3-4 is further described the present invention below in conjunction with accompanying drawing:

With reference to Fig. 3, Hall switch circuit of the present invention comprises the voltage stabilizer 301 to temperature constant, be connected the output of voltage stabilizer 301 and the hall sensing sheet 302 between the ground wire, two Hall voltage differential amplifiers 303 that input end links to each other with hall sensing sheet 302 respectively, the sluggish width that links to each other with the output terminal of this Hall voltage differential amplifier is to the hysteresis comparator 304 of temperature constant, and the output unit 305 that links to each other with the output terminal of this hysteresis comparator 304.This Hall voltage differential amplifier is by the current source I that is proportional to absolute temperature (PTAT) _PTAT, two NPN transistor Q ₁And Q ₂The difference input of forming to with the resistance R of hall sensing sheet material of the same type _EPI1, R _EPI2Constitute.Wherein, PTAT current source I _PTATBe connected two NPN transistor Q ₁And Q ₂Emitter and ground wire between right with this difference input of setovering, and with the resistance R of hall sensing sheet material of the same type _EPI1, R _EPI2As the right load of this difference input, be connected to this NPN transistor Q ₁And Q ₂Collector and the output of voltage stabilizer 301 between, this NPN transistor Q ₁And Q ₂Base stage be connected to hall sensing sheet 302 respectively, two input ends of hysteresis comparator 304 respectively with this NPN transistor Q ₁And Q ₂Collector link to each other.

In the formula (3)

V _COAnd V _RThis temperature coefficient of four can be ignored, and draws B thus _OPAnd B _RPTemperature coefficient be:

$\frac{1}{B}\frac{\∂B}{\∂T}=-\frac{1}{A_V}\frac{{\∂A}_V}{\∂T}-\frac{1}{{\mathrm{\μ}}_H}\frac{{\∂\mathrm{\μ}}_H}{\∂T}---\left(4\right)$

A in the formula (4) _VExpression formula can be written as:

$A_V=G_M{R}_{\mathrm{EPI}}=\frac{I_{\mathrm{PTAT}}}{2V_T}\frac{1}{q{\mathrm{\μ}}_N{N}_{D}t}\frac{L_1}{W_1}---\left(5\right)$

R in the formula (5) _EPIFor with the resistance R of hall sensing sheet material of the same type _FRI1, R _EPI2Value (the two equate), V _TBe thermoelectrical potential, q is an electron charge, μ _N, N _D, t, L ₁, W ₁Be followed successively by resistance R _EPI1, R _EPI2Electron mobility, doping content, thickness, length, width.Because of I _PTATAnd V _TAll be proportional to absolute temperature, so G _MTemperature independent, promptly temperature coefficient is 0.Constant q temperature coefficient is 0, N _D, t, L ₁, W ₁These four temperatures coefficient all can be ignored.So A _VTemperature coefficient only and μ _NRelevant, A _VTemperature coefficient be:

$\frac{1}{A_V}\frac{{\∂A}_V}{\∂T}=-\frac{1}{{\mathrm{\μ}}_N}\frac{{\∂\mathrm{\μ}}_N}{\∂T}---\left(6\right)$

Draw B by formula (6) and formula (4) _OPAnd B _RPTemperature coefficient:

$\frac{1}{B}\frac{\∂B}{\∂T}=\frac{1}{{\mathrm{\μ}}_N}\frac{{\∂\mathrm{\μ}}_N}{\∂T}-\frac{1}{{\mathrm{\μ}}_H}\frac{{\∂\mathrm{\μ}}_H}{\∂T}---\left(7\right)$

Because of resistance R _EPIMaterial type identical with the hall sensing sheet, so the B that draws by formula (7) _OPAnd B _RPTemperature coefficient equal temperature coefficient poor of the temperature coefficient of electron mobility of same material and hall mobility, and the temperature coefficient of the temperature coefficient of the electron mobility of same material and hall mobility equates, so B _OPAnd B _RPTemperature coefficient be zero.

Fig. 4 a-c is other several embodiment of Hall voltage differential amplifier circuit among Fig. 3 (drawing the frame of broken lines part).Wherein, the input of the difference of Fig. 4 a constitutes changing into by two PNP transistors; The difference input of Fig. 4 b constitutes changing into by two PMOS transistors that are operated in subthreshold region; And the input of the difference of Fig. 4 c constitutes changing into by two nmos pass transistors that are operated in subthreshold region.Its bias current and pull-up resistor still be the PTAT current source and with the resistance of hall sensing sheet material of the same type, its essence all is to realize the temperature coefficient and the μ of the gain of Hall voltage differential amplifier _HThe temperature coefficient equal and opposite in direction, the function of opposite in sign.

In Fig. 4 a, the PTAT current source is connected between the output of two transistorized emitters of PNP and voltage stabilizer, and two pull-up resistors are connected between transistorized collector of each PNP and the ground wire, the transistorized base stage of each PNP is connected to the hall sensing sheet respectively, and two input ends of hysteresis comparator link to each other with the transistorized collector of each PNP respectively.

In Fig. 4 b, the PTAT current source is connected between the output of two transistorized source electrodes of PMOS and voltage stabilizer, and two pull-up resistors are connected between each PMOS transistor drain and the ground wire, the transistorized grid of each PMOS is connected to the hall sensing sheet respectively, and two input ends of hysteresis comparator link to each other with each PMOS transistor drain respectively.

In Fig. 4 c, the PTAT current source is connected between the source electrode and ground wire of two nmos pass transistors, and two pull-up resistors are connected between the output of the drain electrode of each nmos pass transistor and voltage stabilizer, the grid of each nmos pass transistor is connected to the hall sensing sheet respectively, and two input ends of hysteresis comparator link to each other with the drain electrode of each nmos pass transistor respectively.

The present invention is right by the input of PTAT current offset difference, realizes the G to temperature constant _MUse again with the resistance of hall sensing sheet material of the same type and do the right load of difference input, realize that thus the temperature coefficient of gain of Hall voltage differential amplifier and the temperature coefficient of hall mobility have equal and opposite in direction, the characteristic of opposite in sign, the two is cancelled out each other and obtains the B of zero temperature _OPAnd B _RPThe actual realization of the present invention simple controllable does not have specific (special) requirements to technology, and it does not deposit process drift influences conforming problem.

Above embodiment only is used for explanation but does not limit the present invention.The present invention also has various deformation and improvement within the scope of the claims.Simple, the equivalence that every foundation claims of the present invention and description are done changes and modifies, and all falls into the claim protection domain of patent of the present invention.

Claims (5)

1. Hall switch circuit with temperature compensation, comprise voltage stabilizer, be connected the output of described voltage stabilizer and the hall sensing sheet between the ground wire, two Hall voltage differential amplifiers that input end links to each other with described hall sensing sheet respectively, the hysteresis comparator that links to each other with the output terminal of described Hall voltage differential amplifier, and the output unit that links to each other with the output terminal of described hysteresis comparator, it is characterized in that, described Hall voltage differential amplifier comprises that the difference input of being made up of two transistors is right, the described difference of setovering is imported the right current source that is proportional to absolute temperature, and is serially connected in the pull-up resistor that one and described hall sensing sheet on each right transistor of described difference input are made with material respectively.

2. Hall switch circuit as claimed in claim 1, it is characterized in that, described difference input is to being made up of two NPN transistor, described current source is connected between the emitter and ground wire of described two NPN transistor, described pull-up resistor is connected between the output of the collector of each NPN transistor and described voltage stabilizer, the base stage of each NPN transistor is connected to described hall sensing sheet respectively, and two input ends of described hysteresis comparator link to each other with the collector of each NPN transistor respectively.

3. Hall switch circuit as claimed in claim 1, it is characterized in that, described difference input is to being made up of two PNP transistors, described current source is connected between the output of described two transistorized emitters of PNP and described voltage stabilizer, described pull-up resistor is connected between transistorized collector of each PNP and the ground wire, the transistorized base stage of each PNP is connected to described hall sensing sheet respectively, and two input ends of described hysteresis comparator link to each other with the transistorized collector of each PNP respectively.

4. Hall switch circuit as claimed in claim 1, it is characterized in that, described difference input is to being made up of two PMOS transistors that are operated in subthreshold region, described current source is connected between the output of described two transistorized source electrodes of PMOS and described voltage stabilizer, and described pull-up resistor is connected between each PMOS transistor drain and the ground wire, the transistorized grid of each PMOS is connected to described hall sensing sheet respectively, and two input ends of described hysteresis comparator link to each other with each PMOS transistor drain respectively.

5. Hall switch circuit as claimed in claim 1, it is characterized in that, described difference input is to being made up of two nmos pass transistors that are operated in subthreshold region, described current source is connected between the source electrode and ground wire of described two nmos pass transistors, described pull-up resistor is connected between the output of the drain electrode of each nmos pass transistor and described voltage stabilizer, the grid of each nmos pass transistor is connected to described hall sensing sheet respectively, and two input ends of described hysteresis comparator link to each other with the drain electrode of each nmos pass transistor respectively.

Images