CN212007570U - Temperature sensor and integrated circuit - Google Patents
Temperature sensor and integrated circuit Download PDFInfo
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- CN212007570U CN212007570U CN202020330368.5U CN202020330368U CN212007570U CN 212007570 U CN212007570 U CN 212007570U CN 202020330368 U CN202020330368 U CN 202020330368U CN 212007570 U CN212007570 U CN 212007570U
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Abstract
The utility model relates to a temperature sensor and an integrated circuit, wherein the temperature sensor comprises a switch circuit, a current generating circuit and a mirror current source circuit; the current generating circuit comprises an MOS tube temperature sensing unit and a BJT temperature sensing unit, one end of the switch circuit is connected with the MOS tube temperature sensing unit and the BJT temperature sensing unit, the other end of the switch circuit is grounded, when the switch circuit is conducted, the MOS tube temperature sensing unit is connected with the mirror current source circuit, the mirror current source circuit outputs a current mirror image with temperature coefficient characteristics generated by the MOS tube temperature sensing unit, when the switch circuit is turned off, the BJT temperature sensing unit is connected with the mirror current source circuit through the MOS tube temperature sensing unit, and the mirror current source circuit outputs the current mirror image with temperature coefficient characteristics generated by the BJT temperature sensing unit. Utilize the temperature sensor of this application, can switch MOS pipe temperature sensing unit and BJT temperature sensing unit as required at any time, realize accurate temperature measurement.
Description
Technical Field
The utility model relates to a temperature control field especially relates to a temperature sensor and integrated circuit.
Background
The temperature sensor has very wide application in the fields of industry, transportation, biological machinery, agriculture and the like. An analog output IC (Integrated Circuit) temperature sensor is a commonly used temperature sensor, and has the advantages of high precision, small size, high resolution, high linearity, and the like. A CMOS (Complementary Metal Oxide Semiconductor) integrated temperature sensor is a commonly used analog IC temperature sensor, and its main implementation includes: MOS (Metal Oxide Semiconductor) Transistor-based temperature sensors and BJT (Bipolar Junction Transistor) -based temperature sensors. MOS transistor based temperature sensor MOS devices typically operate at subthreshold devices, which contain a non-linear factor ζ, with a linearity inferior to BJT based temperature sensors; temperature sensors based on BJTs are susceptible to stress due to BJT devices, and mismatch is more sensitive.
SUMMERY OF THE UTILITY MODEL
In view of the above, it is necessary to provide a temperature sensor and an integrated circuit for solving the problems of the conventional MOS transistor based temperature sensor and the BJT based temperature sensor.
A temperature sensor, comprising: the circuit comprises a switch circuit, a current generation circuit and a mirror current source circuit;
the current generating circuit comprises an MOS tube temperature sensing unit and a BJT temperature sensing unit, the switch circuit is respectively connected with the MOS tube temperature sensing unit and the BJT temperature sensing unit, the BJT temperature sensing unit is connected with the mirror current source circuit through the MOS tube temperature sensing unit, the BJT temperature sensing unit is in short circuit when the switch circuit is conducted, and partial branches in the MOS tube temperature sensing unit are cut off when the switch circuit is cut off.
In one embodiment, the temperature sensor further comprises a PWM generator, the PWM generator comprising a charge and discharge circuit and a comparison circuit;
the first input end of the comparison circuit is connected with the charge and discharge circuit, the second input end of the comparison circuit is connected with a preset threshold voltage source, and the output end of the comparison circuit is connected with the switch circuit.
In one embodiment, the PWM generator further comprises a clock control circuit and a switching circuit;
the switching circuit comprises a control end, a first input end, a second input end and an output end, the control end is connected with the output end of the clock control circuit, the first input end is grounded, the second input end is connected with a preset adjustable voltage source, and the output end is connected with the charge-discharge circuit.
In one embodiment, the switching circuit includes a fourth switch and a fifth switch, the fourth switch includes a control terminal, a first terminal and a second terminal, the fifth switch includes a control terminal, a first terminal, a second terminal and a third terminal, the control terminal of the fourth switch and the control terminal of the second switch are the control terminals of the switching circuit, the first terminal and the second terminal of the fourth switch are the output terminals of the switching circuit, the second terminal of the fifth switch is the first input terminal of the switching circuit, and the third terminal of the fifth switch is the second input terminal of the switching circuit;
the control end of the fourth switch is connected with the output end of the clock control circuit, the first end of the fourth switch is connected with the first end of the fifth switch and the first end of the charge and discharge circuit, and the second end of the fourth switch is connected with the second end of the charge and discharge circuit;
and the control end of the fifth switch is connected with the output end of the clock control circuit, the second end of the fifth switch is grounded, and the third end of the fifth switch is connected with the adjustable voltage source.
In one embodiment, the MOS tube temperature sensing unit comprises a first MOS tube, a second MOS tube and a third MOS tube;
the drain electrode of the first MOS tube, the drain electrode of the second MOS tube and the drain electrode of the third MOS tube are respectively connected with a preset power supply, and the source electrode of the first MOS tube and the source electrode of the second MOS tube are respectively grounded through the switch circuit; and the source electrode of the third MOS tube is connected with the BJT temperature sensing unit through the switch circuit.
In one embodiment, the BJT temperature sensing unit includes a first transistor and a second transistor, a base and a collector of the first transistor and a base and a collector of the second transistor are respectively grounded, an emitter of the first transistor is connected to the source of the first MOS transistor, and an emitter of the second transistor is connected to the sources of the second MOS transistor and the third MOS transistor through the switching circuit.
In one embodiment, the switching circuit includes a first switching leg and a second switching leg;
the first switch branch is connected with the BJT temperature sensing unit in parallel, and the first switch branch is in short circuit with the BJT temperature sensing unit when being conducted;
one end of the second switch branch is connected with a third MOS tube, the other end of the second switch branch is respectively connected with the first switch branch and the BJT temperature sensing unit, and the third MOS tube is turned off when the second switch branch is disconnected.
In one embodiment, the first switch branch comprises a first switch and a second switch, the second switch branch comprises a third switch and a resistor, and the first switch, the second switch and the third switch each comprise a control terminal, a first terminal and a second terminal;
the control ends of the first switch, the second switch and the third switch are respectively connected with the output end of the PWM generator;
a first end of the first switch is connected with a common connection point of a source electrode of the first MOS transistor and an emitting electrode of the first triode, and a second end of the first switch is connected with a common connection point of the first triode, the second triode and the ground;
the first end of the second switch is connected with a common connection point of one end of the resistor and the emitting electrode of the second triode, and the second end of the second switch is connected with a common connection point of the first triode, the second triode and the ground;
and the first end of the third switch is connected with the common connection section of the other end of the resistor and the source electrode of the second MOS tube, and the second end of the third switch is connected with the source electrode of the third MOS tube.
An integrated circuit comprises the temperature sensor.
In one embodiment, the integrated circuit is an MCU chip, a system-on-chip, or a system-in-package chip.
In the temperature sensor and the integrated circuit, the current generating circuit comprises the MOS tube temperature sensing unit and the BJT temperature sensing unit, and the MOS tube temperature sensing unit and the BJT temperature sensing unit are switched through the switch circuit to enable the MOS tube temperature sensing unit and the BJT temperature sensing unit to respectively output currents with temperature coefficient characteristics in different time periods.
Drawings
FIG. 1 is a schematic diagram of a temperature sensor module provided in one embodiment of the present application;
FIG. 2 is a schematic view of a temperature sensor module provided in accordance with yet another embodiment of the present application;
FIG. 3 is a schematic diagram of a temperature sensor circuit according to an embodiment of the present application;
FIG. 4 is a schematic structural diagram of the temperature sensor circuit structure provided in the embodiment shown in FIG. 3 when the switch circuit is turned on;
FIG. 5 is a schematic structural diagram of the temperature sensor circuit structure provided in the embodiment shown in FIG. 3 when the switch circuit is turned off;
fig. 6 is a schematic diagram of a temperature sensor module according to another embodiment of the present application.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1, an embodiment of the present application provides a temperature sensor including a switching circuit 100, a current generating circuit 200, and a current source mirror circuit 300. The switching circuit 100 may be turned on or off under the control of the input PWM pulse signal. The current generating circuit 200 is connected to the switching circuit 100. In this embodiment, the current generating circuit 200 includes a MOS transistor temperature sensing unit 210 and a BJT temperature sensing unit 220. One end of the MOS temperature sensing unit 210 is connected to the BJT temperature sensing unit 220, and the other end is connected to the mirror current source circuit 300. One end of the switching circuit 100 is connected to the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220, respectively, and the other end is grounded. When the switching circuit 100 is turned on, the BJT temperature sensing unit 220 is short-circuited, and when the switching circuit 100 is turned off, part of the branches in the MOS transistor temperature sensing unit 210 are turned off. Specifically, when the switching circuit 100 is turned on, the BJT temperature sensing unit 220 is short-circuited, the MOS transistor temperature sensing unit 210 is connected to the mirror current source circuit 300, a current having a temperature coefficient characteristic is generated by the MOS transistor temperature sensing unit 210, and the mirror current source circuit 300 mirrors the current having the temperature coefficient characteristic to output. When the switching circuit 100 is turned off, the BJT temperature sensing unit 210 is connected to the mirror current source circuit 300 through the MOS transistor temperature sensing unit 210, at this time, the MOS transistor temperature sensing unit 210 cannot generate a current with a temperature coefficient characteristic because part of the branches are turned off, the BJT temperature sensing unit 220 generates a current with a temperature coefficient characteristic, and the other part of the branches, which are not turned off, in the MOS transistor temperature sensing unit 210 serves as a switch, and is connected to the BJT temperature sensing unit 210 and the mirror current source circuit 300, so that the mirror current source circuit 300 mirrors the current with the temperature coefficient characteristic generated by the BJT temperature sensing unit 210 to output. Specifically, in the present embodiment, the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220 may be configured to generate a current having a positive temperature characteristic or a current having a negative temperature coefficient. The current mirror module 300 is connected to the current generating circuit 200, and is configured to mirror the current with the temperature coefficient characteristic to output, so that the external device connected to the temperature sensor calculates the current ambient temperature according to the current with the temperature coefficient characteristic. It is understood that the logic control portion for controlling the switching circuit 100 to be turned on and off can be implemented by the prior art.
In the temperature sensor provided in the above embodiment, the current generating circuit 200 includes both the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220, and the switching circuit 100 is used to switch the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220 to respectively output currents with temperature coefficient characteristics at different time periods.
In one embodiment, as shown in fig. 2, the temperature sensor further includes a PWM generator 400, and the PWM generator 400 is connected to the switching circuit 100 for generating a PWM pulse signal to control the switching circuit 100 to turn on and off. The PWM generator 400 includes a charge and discharge circuit 410 and a comparison circuit 420. A first input terminal of the comparison circuit 420 is connected to the charge and discharge circuit 410, a second input terminal of the comparison circuit 420 is connected to a preset threshold voltage source, and an output terminal of the comparison circuit 420 is connected to the switch circuit 100. The comparison circuit 420 is configured to compare the voltage of the charge/discharge circuit 410 with a threshold voltage, and output a first level signal when the voltage of the charge/discharge circuit 410 is greater than or equal to the threshold voltage, and output a second level signal when the voltage of the charge/discharge circuit 410 is less than the threshold voltage to form a PWM pulse signal. Alternatively, the threshold voltage source may be a voltage source built in the temperature sensor, or may be implemented by an external voltage source.
Taking the circuit shown in fig. 3 as an example, the charging and discharging circuit 410 may be implemented by a capacitor C, and the comparing circuit 420 may be implemented by an operational amplifier a. The operational amplifier A comprises a first input end, a second input end and an output end, wherein the first input end is connected with the second end of the capacitor C and used for inputting a capacitor voltage Vc, and the second input end is used for inputting a threshold voltage Vthrehold. The first input terminal is a positive phase input terminal, the second input terminal is an inverted phase input terminal, and when the capacitor voltage Vc is greater than the threshold voltage VthreholdWhen the voltage Vc of the capacitor is larger than the threshold voltage V, the operational amplifier A outputs a high level signalthreholdThe operational amplifier a outputs a low level signal, and the PWM pulse signal is composed of a high level signal and a low level signal alternately.
Further, the PWM generator 400 further includes a clock control circuit 430 and a switching circuit 440. The switching circuit comprises a control end, a first input end, a second input end and an output end. The control terminal of the switching circuit 440 is connected to the output terminal of the clock control circuit 430, the first input terminal of the switching circuit 440 is grounded, the second input terminal of the switching circuit 440 is connected to a preset adjustable voltage source, and the output terminal of the switching circuit 440 is connected to the charging and discharging circuit 410. Alternatively, the adjustable voltage source may be a built-in voltage source of the temperature sensor, or may be implemented by an external voltage source. The clock control circuit 430 may control the switching circuit 440 such that the switching circuit 440 controls the charging and discharging circuit 410 to switch between the charging state and the discharging state.
Specifically, as shown in fig. 3, the switching circuit 440 includes a fourth switch S4 and a fifth switch S5. The fourth switch S4 and the fifth switch S5 are controlled by the clock control circuit 430. The fourth switch S4 includes a control terminal, a first terminal, and a second terminal. A control terminal of the fourth switch S4 is connected to the output terminal of the clock control circuit 430, a first terminal of the fourth switch S4 is connected to the first terminal of the fifth switch S5 and the first terminal of the charge and discharge circuit 410, and a second terminal of the fourth switch S4 is connected to the second terminal of the charge and discharge circuit 410 and the first input terminal of the operational amplifier a. In this embodiment, the clock signal generated by the clock control circuit 430 controls the fourth switch S4 to be turned on or off. When the clock control circuit 430 outputs the first level signal, the fourth switch S4 is closed, and when the clock control circuit 430 outputs the second level signal, the fourth switch S4 is turned off. In some alternative embodiments, clock control circuit 430 may be replaced by an external clock source.
The fifth switch S5 includes a control terminal, a first terminal, a second terminal, and a third terminal. A control terminal of the fifth switch S5 is connected to the output terminal of the clock control circuit 430, a first terminal of the fifth switch S5 is connected to a common connection point between a first terminal of the fourth switch S4 and a first terminal of the capacitor C, a second terminal of the fifth switch S5 is grounded, and a third terminal of the fifth switch S5 is connected to a preset adjustable voltage source. When the clock control circuit 430 outputs the first level signal, the first terminal and the second terminal of the fifth switch S5 are connected, that is, the capacitor C is grounded through the fifth switch S5, and at this time, the charge accumulated on the capacitor C will be discharged through the fifth switch S5, that is, the capacitor C is controlled to discharge. When the clock control circuit 430 outputs the second level signal, the first terminal and the third terminal of the fifth switch S5 are connected, that is, the output voltage V of the adjustable voltage sourceadjThe capacitor C is charged through the fifth switch S5.
Alternatively, the first level signal of the clock control circuit 430 is a high level signal, and the second level signal is a low level signal; alternatively, the first level signal of the clock control circuit 430 is a low level signal and the second level signal is a high level signal. It should be noted that the control logic of the clock control circuit 430 in this embodiment can be implemented by the prior art, which is not the focus of this application.
In a specific embodiment, taking the circuit shown in fig. 3 as an example, when the clock control circuit 430 outputs the first level signal, the fourth switch S4 is closed, the first terminal and the second terminal of the fifth switch S5 are connected, that is, the capacitor C is short-circuited, and the fifth switch S5 is connected to the ground terminal, the capacitor C is in a discharging state, and the PWM generator 400 is in a reset state. When the clock control circuit 430 outputs the second level signal, the fourth switch S4 is turned off, and the first terminal and the third terminal of the fifth switch S5 are connected, that is, the adjustable voltage source charges the capacitor C through the switch S5. In the charging process, when the voltage of the capacitor C is greater than or equal to the threshold voltage, the operational amplifier A outputs a high level signal, when the voltage of the capacitor C is smaller than the threshold voltage, the operational amplifier A outputs a low level signal, and the alternating high and low level signals form a PWM pulse signal. Furthermore, the duty ratio of the PWM pulse signal can be adjusted by adjusting the size of the adjustable voltage source. It is understood that the method for adjusting the duty ratio of the PWM pulse signal can be implemented by the prior art, and is not a protection point of the present application.
The PWM generator 400 generates PWM pulse signals for controlling the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220 to operate. Referring to fig. 3, in one embodiment, the MOS temperature sensing unit 210 includes a first MOS transistor M1, a second MOS transistor M2, and a third MOS transistor M3. The first MOS transistor M1, the second MOS transistor M2, and the third MOS transistor M3 may all be N-type transistors or P-type transistors. The gates of the first MOS transistor M1, the second MOS transistor M2 and the third MOS transistor M3 are connected, and the drain of the first MOS transistor M1, the drain of the second MOS transistor M2 and the drain of the third MOS transistor M3 are respectively connected to a preset power supply VDD through the mirror current source circuit 300. The preset power supply VDD is used for providing working voltage for the mirror current source, can be built in the temperature sensor, and can also be realized through an external power supply. The mirror current source circuit 300 includes a first mirror current source 310, a second mirror current source 320, and a third mirror current source 330, and the first mirror current source 310, the second mirror current source 320, and the third mirror current source 330 are respectively connected to a preset power supply VDD. The drain of the first MOS transistor is connected to the first mirror current source 310, and the drains of the second MOS transistor M2 and the third MOS transistor M3 are connected to the second mirror current source 320, respectively. The source of the first MOS transistor M1 and the source of the second MOS transistor M2 are grounded through the switch circuit 100, respectively, and the source of the third MOS transistor M3 is connected to the BJT temperature sensing unit 220 through the switch circuit 100.
Further, the BJT temperature sensing unit 220 includes a first transistor Q1 and a second transistor Q2, wherein the base and the collector of the first transistor Q1 and the base and the collector of the second transistor Q2 are respectively grounded, the emitter of the first transistor Q1 is connected to the source of the first MOS transistor M1, and the emitter of the second transistor Q2 is connected to the sources of the second MOS transistor M2 and the third MOS transistor M3 through the switching circuit 100.
Further, the switching circuit 100 includes a first switching leg and a second switching leg. The first switching branch is connected in parallel with the BJT temperature sensing unit 230, and when the first switching branch is turned on, the BJT temperature sensing unit 230 is short-circuited. One end of the second switch branch is connected with the third MOS transistor M3, the other end of the second switch branch is respectively connected with the first switch branch and the BJT temperature sensing unit 220, and the second switch branch turns off the third MOS transistor M3 when being disconnected. Specifically, the first switching leg includes a first switch S1 and a second switch S2, and the second switching leg includes a third switch S3 and a resistor R1. The first switch S1, the second switch S2, and the third switch S3 each include a control terminal, a first terminal, and a second terminal. Control terminals of the first switch S1, the second switch S2, and the third switch S3 are respectively connected to the output terminal of the PWM generator 400. A first end of the first switch S1 is connected to a common connection point between the source of the first MOS transistor M1 and the emitter of the first transistor Q1, and a second end of the first switch S1 is connected to a common connection point between the first transistor Q1 and the second transistor Q2, and ground. A first terminal of the second switch S2 is connected to a common connection point of one terminal of the resistor R1 and the emitter of the second transistor Q2. A second terminal of the second switch S2 is connected to a common connection of the first transistor Q1 and the second transistor Q2 to ground. The first end of the third switch S3 is connected to the common connection point of the other end of the resistor R1 and the source of the second MOS transistor, and the second end of the third switch S3 is connected to the source of the third MOS transistor M3. The PWM pulse signal outputted from the PWM generator 400 may control the first switch S1, the second switch S2, and the third switch S3 to be turned on and off, and when the PWM generator 400 outputs a first level, the first switch S1, the second switch S2, and the third switch S3 are controlled to be turned on, and when the PWM generator 400 outputs a second level, the first switch S1, the second switch S2, and the third switch S3 are controlled to be turned off. The first level is a high level and the second level is a low level, or the first level is a low level and the second level is a high level.
When the PWM pulse signal controls the first switching branch and the second switching branch to be turned on, the BJT temperature sensing unit 220 is in a short-circuit state, and the first MOS transistor M1, the second MOS transistor M2, and the third MOS transistor M3 are in a sub-threshold region and generate a current with a temperature coefficient characteristic. When the first switch branch and the second switch branch are controlled to be switched off by the PWM pulse signal, the first MOS tube M1 and the second MOS tube M2 form a clamping circuit, the third MOS tube M3 is disconnected with the circuit, so that the source voltages of the first MOS tube M1 and the second MOS tube M2 are the same, and the first triode Q1 and the second triode Q2 generate currents with temperature coefficient characteristics.
Specifically, when the PWM pulse signal controls the first switch S1, the second switch S2 and the third switch S3 to be turned on, the equivalent circuit of the temperature sensor is as shown in fig. 4, the BJT temperature sensing unit 220 is short-circuited by the switch circuit 100, the source of the first MOS transistor M1 is grounded through the first switch S1, and the sources of the second MOS transistor M2 and the third MOS transistor M3 are grounded through the resistor R1 and the switch S2, respectively. At this time, the current with the temperature coefficient characteristic is provided by the first MOS transistor M1, the second MOS transistor M2 and the third MOS transistor M3 operating in the sub-threshold region. Assuming that the current with temperature coefficient is IptatThen, the current expression is as follows:
Iptat＝(VGS1-VGS2)/R (1)
wherein VGS1Is the gate-source voltage difference, V, of the first MOS transistor M1GS2Is the gate-source voltage difference of the second MOS transistor M2.
The current of the MOS tube working in the subthreshold region is as follows:
wherein the content of the first and second substances,
i.e., the width-to-length ratio of the MOS transistor, mu represents the carrier mobility,sidenotes the dielectric constant, phi, of the semiconductor material siliconSRepresents the surface potential of the MOS transistor, phiBExpressing the substrate Fermi potential, N, of the MOS transistorchThe substrate doping concentration of the MOS transistor is shown,
represents the thermoelectric potential of the MOS tube, wherein k is Boltzmann constant, T is the thermodynamic temperature, i.e., absolute temperature, and q is the electronic charge (1.6 × 10)–19C)。
And because of
Equation (2) and equation (3) are combined to obtain:
and calculating to obtain:
thus:
let n (T) be ≈ n (T)0)，
It is possible to obtain:
wherein, KG＝KT+Vgs(T0)-Vth(T0)-Voff。
In the above formula, T represents the current actual temperature, and T0 representsReference temperature, VoffRepresenting a correction constant term. Due to KGUsually a negative value, so that V can be seen from the formula (7)gsDecreases with increasing temperature, i.e. has a negative temperature coefficient, so Δ VgsHas a positive temperature coefficient. Thus IPTAT_MOSThe current is as follows:
that is, the MOS transistor temperature sensing unit may generate a current having a positive temperature coefficient.
When the PWM pulse signal controls the first switch S1, the second switch S2, and the third switch S3 to turn off, the equivalent circuit is as shown in fig. 5, the third MOS transistor M3 is turned off, and the first MOS transistor M1 and the second MOS transistor M2 form a clamp circuit, so that the source voltages of the first MOS transistor M1 and the second MOS transistor M2 are equal. At this time, a current having a temperature coefficient characteristic is generated by the first transistor Q1 and the second transistor Q2. The current expression is as follows:
I＝(VBE1-VBE2)/R (8)
wherein, VBE1The voltage difference between the base and the emitter of the first triode Q1 is shown as VBE2The voltage difference between the base and the emitter of the second transistor Q2 is shown, and R is the resistance value of the resistor R1.
For a bipolar device, the collector current is:
IC＝IS exp(VBE/VT) (9)
wherein, IsIndicating saturation current, V, of BJT transistorBERepresenting the voltage difference between the base and the emitter of the BJT transistor,
representing the thermoelectric potential of a BJT triode, k is the Boltzmann constant, T is the thermodynamic, i.e., absolute, temperature, and q is the electronic charge (1.6 × 10)–19C)。
It is possible to obtain:
due to the fact that
Thus, VBEHaving a negative temperature characteristic, further DeltaVBEWith positive temperature characteristics, the current expression is:
that is, the BJT temperature sensing unit may generate a current having a positive temperature coefficient.
From the above formula, when the PWM pulse signal controls the switch circuit 100 to be turned on, the MOS transistor temperature sensing unit 210 generates a current with a positive temperature coefficient, and when the PWM pulse signal controls the switch circuit 100 to be turned off, the BJT temperature sensing unit 220 generates a current with a positive temperature coefficient. The current mirror current source module 300 is connected to the current generating circuit, and is configured to mirror the current with positive temperature coefficient. The temperature sensor controls the on and off of the switching circuit 100 by generating PWM pulse signals with adjustable pulse width, and switches the MOS tube temperature sensing unit 210 and the BJT temperature sensing unit 220 at any time according to requirements to generate current with positive temperature coefficient, thereby avoiding precision deviation caused by packaging stress when only the BJT temperature sensor is adopted or errors caused by nonlinear factors when only the MOS tube temperature sensor is adopted, and realizing accurate temperature measurement
Further, referring to fig. 6, in one embodiment, the temperature sensor further includes a current detection circuit 500 connected to the mirror current source circuit 300, specifically, the current detection circuit 500 is connected to the third mirror current source 330, and is configured to sample a current with a temperature coefficient characteristic and determine a temperature corresponding to the current according to the temperature coefficient characteristic of the current. As shown in fig. 3, the current detection circuit 500 may be an ADC (Analog-to-digital converter). In other alternatives, the current detection circuit 500 may also be an analog front-end (AFE) circuit or other circuit with signal acquisition and processing functions.
In the temperature sensor provided in the above embodiment, the current generating circuit 200 includes both the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220, and the PWM generator 400 outputs PWM pulses with different duty ratios to switch the MOS transistor temperature sensing unit 210 and the BJT temperature sensing unit 220 to output currents with temperature coefficient characteristics at different time periods, respectively.
The application also provides an integrated circuit comprising the temperature sensor. Alternatively, the temperature sensor may be integrated In an MCU, or may be integrated In an SOC (System On a Chip) or an SIP (System In a Package).
The integrated circuit provided with the temperature sensor comprises a MOS tube temperature sensing unit and a BJT temperature sensing unit. The PWM generator is used for generating PWM pulse signals to control the switch-off of the switch circuit, and then the MOS tube temperature sensing unit and the BJT temperature sensing unit can be switched through the switch circuit to enable the MOS tube temperature sensing unit and the BJT temperature sensing unit to respectively output currents with temperature coefficient characteristics in different periods of time, the integrated circuit can calculate the current ambient temperature according to the currents with the temperature coefficient characteristics, and therefore precision deviation caused by packaging stress when only the BJT temperature sensor is adopted in the traditional technology or errors caused by nonlinear factors when only the MOS tube temperature sensor is adopted are avoided, and accurate temperature measurement is achieved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A temperature sensor, comprising: the circuit comprises a switch circuit, a current generation circuit and a mirror current source circuit;
the current generating circuit comprises an MOS tube temperature sensing unit and a BJT temperature sensing unit, the switch circuit is respectively connected with the MOS tube temperature sensing unit and the BJT temperature sensing unit, and the BJT temperature sensing unit is connected with the mirror current source circuit through the MOS tube temperature sensing unit;
when the switching circuit is switched on, the BJT temperature sensing unit is short-circuited, and when the switching circuit is switched off, part of branches in the MOS tube temperature sensing unit are switched off.
2. The temperature sensor of claim 1, further comprising a PWM generator, the PWM generator comprising a charge-discharge circuit and a comparison circuit;
the first input end of the comparison circuit is connected with the charge and discharge circuit, the second input end of the comparison circuit is connected with a preset threshold voltage source, and the output end of the comparison circuit is connected with the switch circuit.
3. The temperature sensor of claim 2, wherein the PWM generator further comprises a clock control circuit and a switching circuit;
the switching circuit comprises a control end, a first input end, a second input end and an output end, the control end of the switching circuit is connected with the output end of the clock control circuit, the first input end of the switching circuit is grounded, the second input end of the switching circuit is connected with a preset adjustable voltage source, and the output end of the switching circuit is connected with the charging and discharging circuit.
4. The temperature sensor of claim 3, wherein the switching circuit comprises a fourth switch comprising a control terminal, a first terminal, and a second terminal, and a fifth switch comprising a control terminal, a first terminal, a second terminal, and a third terminal;
the control end of the fourth switch is connected with the output end of the clock control circuit, the first end of the fourth switch is connected with the first end of the fifth switch and the first end of the charge and discharge circuit, and the second end of the fourth switch is connected with the second end of the charge and discharge circuit;
and the control end of the fifth switch is connected with the output end of the clock control circuit, the second end of the fifth switch is grounded, and the third end of the fifth switch is connected with the adjustable voltage source.
5. The temperature sensor according to claim 4, wherein the MOS tube temperature sensing unit comprises a first MOS tube, a second MOS tube and a third MOS tube;
the drain electrode of the first MOS tube, the drain electrode of the second MOS tube and the drain electrode of the third MOS tube are respectively connected with a preset power supply, and the source electrode of the first MOS tube and the source electrode of the second MOS tube are respectively grounded through the switch circuit; and the source electrode of the third MOS tube is connected with the BJT temperature sensing unit through the switch circuit.
6. The temperature sensor according to claim 5, wherein the BJT temperature sensing unit comprises a first transistor and a second transistor, a base and a collector of the first transistor and a base and a collector of the second transistor are respectively grounded, an emitter of the first transistor is connected to a source of the first MOS transistor, and an emitter of the second transistor is connected to sources of the second MOS transistor and the third MOS transistor through the switching circuit.
7. The temperature sensor of claim 6, wherein the switching circuit comprises a first switching leg and a second switching leg;
the first switch branch is connected with the BJT temperature sensing unit in parallel, and the first switch branch is in short circuit with the BJT temperature sensing unit when being conducted;
one end of the second switch branch is connected with a third MOS tube, the other end of the second switch branch is respectively connected with the first switch branch and the BJT temperature sensing unit, and the third MOS tube is turned off when the second switch branch is disconnected.
8. The temperature sensor of claim 7, wherein the first switching leg comprises a first switch and a second switch, the second switching leg comprises a third switch and a resistor, the first switch, the second switch, and the third switch each comprise a control terminal, a first terminal, and a second terminal;
the control ends of the first switch, the second switch and the third switch are respectively connected with the output end of the PWM generator;
a first end of the first switch is connected with a common connection point of a source electrode of the first MOS transistor and an emitting electrode of the first triode, and a second end of the first switch is connected with a common connection point of the first triode, the second triode and the ground;
the first end of the second switch is connected with a common connection point of one end of the resistor and the emitting electrode of the second triode, and the second end of the second switch is connected with a common connection point of the first triode, the second triode and the ground;
and the first end of the third switch is connected with the common connection section of the other end of the resistor and the source electrode of the second MOS tube, and the second end of the third switch is connected with the source electrode of the third MOS tube.
9. An integrated circuit comprising a temperature sensor according to any of claims 1-8.
10. The integrated circuit of claim 9, wherein the integrated circuit is an MCU chip, a system-on-chip, or a system-in-package chip.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114879808A (en) * | 2022-04-08 | 2022-08-09 | 北京智芯微电子科技有限公司 | Temperature detection chip, PTAT circuit thereof and temperature sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114879808A (en) * | 2022-04-08 | 2022-08-09 | 北京智芯微电子科技有限公司 | Temperature detection chip, PTAT circuit thereof and temperature sensor |
| CN114879808B (en) * | 2022-04-08 | 2024-01-23 | 北京智芯微电子科技有限公司 | Temperature detection chip, PTAT circuit thereof and temperature sensor |
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