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 relation of material self do
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 is 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 is as shown in Figure 2, comprises voltage stabilizer 201, hall sensing sheet 202, Hall voltage differential amplifier 203, hysteresis comparator 204 and output unit 205.
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:
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 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 one Chinese patent application of CN2884693Y has been announced a kind of Hall switcher circuit and delay comparator circuit, 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 temperature compensation and the circuit thereof of a kind of hall effect circuit of announcing of the one Chinese patent application of CN101290233A 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 realize the item addition with the item of a positive temperature coefficient (PTC) and a negative temperature coefficient obtain another positive temperature coefficient with minimizing μ
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 matters that the present invention will solve 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 said voltage stabilizer and the hall sensing sheet between the ground wire; Two Hall voltage differential amplifiers that input end links to each other with said hall sensing sheet respectively, the hysteresis comparator that links to each other with the output terminal of said Hall voltage differential amplifier, and the output unit that links to each other with the output terminal of said hysteresis comparator; It is characterized in that; Said Hall voltage differential amplifier comprises that the difference input of being made up of two transistors is right, the right current source that is proportional to absolute temperature of said difference input of setovering, and be serially connected in the pull-up resistor that one and said hall sensing sheet on each right transistor of said difference input are processed with material respectively.
The Hall switch circuit of the band temperature compensation that the present invention provides is through 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 further describes 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 are 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
2The output of collector and 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:
A in the formula (4)
VExpression formula can be written as:
R in the formula (5)
EPIFor with the resistance R of hall sensing sheet material of the same type
EPI1, 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:
Draw B by formula (6) and formula (4)
OPAnd B
RPTemperature coefficient:
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 temperature coefficient and hall mobility of the electron mobility of same material, 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 the other several kinds of 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 drain electrode and voltage stabilizer of each nmos pass transistor; 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 through 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; Temperature coefficient and the temperature coefficient of hall mobility of realizing the gain of Hall voltage differential amplifier thus have equal and opposite in direction, the characteristic of opposite in sign, and the two is cancelled out each other and obtains the B of zero temperature
PPAnd 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.