CN117713693A - High-side oscillating circuit of inductive sensor - Google Patents
High-side oscillating circuit of inductive sensor Download PDFInfo
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- CN117713693A CN117713693A CN202311739453.1A CN202311739453A CN117713693A CN 117713693 A CN117713693 A CN 117713693A CN 202311739453 A CN202311739453 A CN 202311739453A CN 117713693 A CN117713693 A CN 117713693A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/08—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance
- H03B5/12—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device
- H03B5/1231—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element comprising lumped inductance and capacitance active element in amplifier being semiconductor device the amplifier comprising one or more bipolar transistors
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Abstract
The invention discloses an inductance type sensor high-side oscillating circuit, which comprises: one end of the excitation source module is connected with one output end of the current mirror module; the other end of the excitation source module is connected with a first bias constant current source; the control input end of the excitation source module is connected with a bias voltage source; the two ports on one side of the negative feedback loop are connected with the excitation source module; two ports on the other side of the negative feedback loop are respectively connected with the LC resonant circuit and the detection resistor; the input side of the pair of tube circuits is connected with two ends of the LC resonance circuit; the output side of the tube circuit is connected with one port of the negative feedback loop; one end of the LC resonance circuit is connected with the current mirror and the high-side voltage; wherein, a transistor in the negative feedback loop and the excitation source module are in mirror image structures. The embodiment can realize the driving of the resonant circuit at the high side, and solves the problem that the requirement of high-side application cannot be met when the resonant circuit is arranged at the low side by the traditional inductive sensor.
Description
Technical Field
The invention relates to the technical field of inductive sensors, in particular to a high-side oscillating circuit of an inductive sensor.
Background
In the fields of industrial automation, mechanical manufacturing, electronic equipment, automobiles and the like, the inductance type sensor is widely used by virtue of the characteristics of non-contact measurement, oil stain resistance, strong anti-interference capability, high sensitivity, high reliability and the like. Inductive sensors utilize the principle of electromagnetic induction to detect a metal object by an alternating magnetic field generated around an induction coil. When the metal object approaches this magnetic field and reaches an induced distance, eddy currents are generated within the metal object, resulting in damping of the oscillations, and thus stopping the oscillations. The oscillation and the vibration stopping change of the oscillator are processed by a post-stage amplifying circuit and converted into a switching signal to trigger a driving control device, so that the non-contact detection purpose is achieved. Thus, the inductance type sensor oscillation circuit serves as an excitation source of the coil, and plays a role in the whole inductance type sensor circuit.
In some existing inductive sensor oscillating circuit schemes, as shown in fig. 1, it is common to place the oscillating circuit on the low side to drive the induction coil. Specifically, the coil and the capacitor in the resonant circuit are connected in parallel, one side is grounded, and the other side is connected with the end of the oscillating circuit. However, in some high-side applications, the entire inductive sensor circuit needs to be connected as a module to the circuit, and the low-side oscillating circuit cannot meet the requirement.
Disclosure of Invention
In view of this, an embodiment of the present invention provides a high-side oscillating circuit of an inductive sensor, including:
one end of the excitation source module is connected with one output end of the current mirror module; the other end of the excitation source module is connected with a first bias constant current source; the control input end of the excitation source module is connected with a bias voltage source;
the two ports on one side of the negative feedback loop are connected with the excitation source module; two ports on the other side of the negative feedback loop are respectively connected with the LC resonant circuit and the detection resistor;
the input side of the pair of tube circuits is connected with two ends of the LC resonance circuit; the output side of the tube circuit is connected with one port of the negative feedback loop;
one end of the LC resonance circuit is connected with the current mirror and the high-side voltage;
wherein, a transistor in the negative feedback loop and the excitation source module are in mirror image structures.
Optionally, the current mirror comprises:
the base electrode and the collector electrode of the first transistor T1 are in short circuit, and the emitter electrode of the first transistor T1 is connected with high-side voltage;
a second transistor T2, the base of which is connected with the base of the first transistor T1; the emitter of the second transistor is connected to a high side voltage.
Optionally, the excitation source module includes:
a third transistor T3 having a base connected to a bias voltage source; the collector of the third transistor T3 is connected to the collector of the first transistor T1; an emitter of the third transistor T3 is connected with one end of the first bias constant current source Ibias 1; the other end of the first bias constant current source Ibias1 is grounded.
Optionally, the negative feedback loop comprises:
a fourth transistor T4 having a collector connected to the collector of the second transistor T2; an emitter of the fourth transistor T4 and an emitter of the third transistor T3 are commonly connected to one end of the first bias constant current source Ibias 1;
a thirteenth transistor T13 having a base connected to the collector of the fourth transistor T4; an emitter of the thirteenth transistor T13 is connected to the base of the fourth transistor T4; the emitter of the thirteenth transistor T13 is also grounded through the detection resistor Radj; the collector of the thirteenth transistor T13 is connected to the output of the pair of transistor circuits.
Optionally, the pair tube circuit comprises:
an eleventh transistor T11 having a collector connected to the high-side voltage and one end of the LC resonant circuit; the base electrode of the eleventh transistor T11 is connected with the high-side voltage through the first branch circuit; an emitter of the eleventh transistor T11 is connected to a collector of the thirteenth transistor T13;
a twelfth transistor T12 having a collector connected to the other end of the LC resonant circuit; the base electrode of the twelfth transistor T12 is connected with the other end of the LC resonance circuit through the second branch; an emitter of the twelfth transistor T12 is connected to a collector of the thirteenth transistor T13.
Optionally, the first branch includes: a fifth transistor T5, a sixth transistor T6, and a seventh transistor T7; the second branch includes: an eighth transistor T8, a ninth transistor T9, and a tenth transistor T10;
wherein, the bases of the fifth transistor T5, the sixth transistor T6, the seventh transistor T7, the eighth transistor T8, the ninth transistor T9 and the tenth transistor T10 are respectively short-circuited with the collectors thereof;
the collector of the fifth transistor T5 is connected with high-side voltage; an emitter of the fifth transistor T5 is connected to a collector of the sixth transistor T6; an emitter of the sixth transistor T6 is connected to a collector of the seventh transistor T7; an emitter of the seventh transistor T7 is connected to a base of the eleventh transistor T11;
the collector of the eighth transistor T8 is connected to the other end of the LC resonance circuit and the collector of the eleventh transistor T11; an emitter of the eighth transistor T8 is connected to a collector of the ninth transistor T9; an emitter of the ninth transistor T9 is connected to a collector of the tenth transistor T10; an emitter of the tenth transistor T10 is connected to a base of the twelfth transistor T12.
Optionally, the method further comprises:
one end of the second bias constant current source Ibias2 is connected with the emitter of the seventh transistor T7, and the other end of the second bias constant current source Ibias2 is grounded;
and one end of the third bias constant current source Ibias3 is connected with the bases of the tenth transistor T10 and the twelfth transistor T12, and the other end of the third bias constant current source Ibias3 is grounded.
Optionally, the method further comprises:
an arithmetic circuit for collecting and calculating a detection signal through the emitter and/or the base of the fourth transistor T4; the arithmetic circuit also connects the negative feedback control signal to the high-side oscillating circuit through the collector and/or emitter of the fourth transistor T4.
The invention has the beneficial effects that:
1. the embodiment of the invention provides a high-side oscillating circuit of an inductive sensor, which can realize the driving of a resonant circuit at a high side. The problem that the requirement of high-side application cannot be met when the resonant circuit is arranged on the low side of the traditional inductive sensor is solved.
2. Compared with the traditional oscillating circuit, the high-side oscillating circuit disclosed by the invention has a simple circuit topology structure, greatly reduces the complexity of the circuit structure and further reduces the cost.
3. The circuit provided by the invention has few devices, has low requirement on device matching, reduces system power consumption, and improves the anti-interference performance of the circuit.
4. The high-side oscillating circuit provided by the invention uses the positive feedback control loop and the negative feedback control loop at the same time, can realize real-time automatic equalization of the control of the oscillating circuit, and ensures the stability of the circuit.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and should not be construed as limiting the invention in any way, in which:
FIG. 1 shows a block diagram of a prior art low side tank circuit;
FIG. 2 shows a diagram of a high-side oscillating circuit of an inductive sensor in an embodiment of the invention;
fig. 3 shows a diagram of another high-side oscillating circuit of an inductive sensor according to an embodiment of the invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
The embodiment of the invention provides a high-side oscillating circuit of an inductive sensor, which comprises an excitation source module, a current mirror module, a negative feedback loop, a pair tube circuit, an LC resonance circuit, a high-side voltage and bias voltage source, wherein one end of the excitation source module is connected with one output end of the current mirror module; the other end of the excitation source module is connected with a first bias constant current source; the control input end of the excitation source module is connected with a bias voltage source; two ports on one side of the negative feedback loop are connected with the excitation source module; two ports on the other side of the negative feedback loop are respectively connected with the LC resonant circuit and the detection resistor; the input side of the pair tube circuit is connected with two ends of the LC resonance circuit; the output side of the tube circuit is connected with one port of the negative feedback loop; one end of the LC resonance circuit is connected with the current mirror module and the high-side voltage; wherein, a transistor in the negative feedback loop and the excitation source module are in mirror image structures.
As shown in fig. 2, an LC resonant circuit 120 for generating an alternating induced magnetic field; the high-side oscillating circuit 110 is configured to provide an excitation signal for the LC resonant circuit 120, so that the coil L in the LC resonant circuit generates an alternating induction magnetic field; a first connection line 101 for connecting one end of the LC resonant circuit 120 to a circuit high-side VDD power supply; and a second connection line 102 for connecting the other end of the LC resonant circuit 120 to the high-side resonant circuit 110.
The LC resonant circuit 120 includes a resonant coil L and a resonant capacitor C, and the resonant coil L is connected in parallel with the resonant capacitor C. One end of the LC resonance circuit 120 is connected to a circuit high side (VDD) through a first connection line 101, and the other end of the LC resonance circuit 120 is connected to the high side oscillation circuit 110 through a second connection line 102. Specifically, the second connection line 102 connects the other end of the LC resonance circuit 120 to the transistors T8 and T11 in the high-side oscillation circuit 110, and is the collectors of the transistors T8 and T11. The LC resonant circuit 120 receives the high-frequency oscillation signal supplied from the high-side oscillation circuit 110, generates an alternating induction magnetic field around the coil L in the LC resonant circuit 120, and when a detection object including conductivity approaches the coil L, changes the alternating induction magnetic field generated around the coil L.
The LC resonant circuit 120 includes a resonant inductance L and a resonant capacitance C, and the resonant inductance L is connected in parallel with the resonant capacitance C. The LC resonant circuit 120 is connected to the high-side oscillating circuit 110 through the first connection line 101, and is connected to the emitter of the transistor T3 in the high-side oscillating circuit 110.
Wherein, the resonant frequency f generated by the resonant inductance L and the resonant capacitance C satisfies:
where f represents the resonant frequency, L represents the value of the inductance, and C represents the value of the capacitance. The formula 2 pi is a constant, approximately equal to 6.28.
It is emphasized that the resonant frequency setting of an inductive sensor should be determined according to the specific application requirements and a series of factors and parasitics are typically considered. These factors may include the operating range of the sensor, environmental interference, energy consumption, sensitivity, and signal to noise ratio, among others. Meanwhile, the parasitic effects may involve parasitic capacitance, parasitic resistance, parasitic inductance, and the like.
The high-side oscillating circuit 110 is connected to the LC resonant circuit 120, and is configured to provide an excitation signal for the LC resonant circuit 120, and simultaneously fuse and detect the state characteristics of the LC resonant circuit 120. The state characteristics include frequency characteristics, current characteristics, voltage characteristics, and the like.
The physical topological connection relationship in fig. 2 is as follows:
the base electrode and the collector electrode of the first transistor T1 are short-circuited and are connected with the base electrode of the second transistor T2 to form a current mirror, so that the second transistor T2 copies the proportion of the current of the first transistor T1; emitters of the first transistor T1 and the second transistor T2 are commonly connected to VDD; the bias voltage VB is connected with the base electrode of the third transistor T3 and provides bias voltage for the third transistor T3; the collector of the third transistor T3 is connected to the collector of the transistor T1, the emitter of the third transistor T3 is connected to the emitter of the fourth transistor T4, and is commonly connected to one end of the first bias constant current source Ibias1, and the other end of the first bias constant current source Ibias1 is grounded; the collector of the fourth transistor T4 is connected with the collector of the second transistor T2, the base of the fourth transistor T4 is connected with the emitter of the thirteenth transistor T13 and one end of the first resistor Radj, and the other end of the resistor Radj is grounded; the bases of the fifth transistor T5, the sixth transistor T6 and the seventh transistor T7 are respectively connected to the collectors of the fifth transistor T5, the bases of the fifth transistor T6 and the seventh transistor T7 are connected to the collectors of the fifth transistor T6 and the seventh transistor T7 respectively to form a diode connection mode of the transistors, the collector of the fifth transistor T5 is connected to VDD, the collector of the fifth transistor T6 is connected to the emitter of the fifth transistor T5, and the collector of the fifth transistor T7 is connected to the emitter of the fifth transistor T6; similarly, the eighth transistor T8, the ninth transistor T9 and the tenth transistor T10 are respectively diode-connected, and the emitter of the T10 is connected to one end of the third bias constant current Ibias3, and the other end of the Ibias3 is grounded; the collector of the transistor T8 is connected to the collector of the eleventh transistor T11 and to the LC tank 120 through a second connection line; the eleventh transistor T11 and the twelfth transistor T12 form a pair of transistors, and the bases of the transistors are respectively connected to the emitters of the transistor T7 and the transistor T10; the emitters of T11 and T12 are connected and commonly connected to the collector of thirteenth transistor T13, and the base of T13 is connected to the collectors of T2 and T4; the collector of the twelfth transistor T2 is connected to VDD.
The first transistor T1 and the second transistor T2 form a mirror image connection, so that the first transistor T1 can follow the current of the second transistor T2. Specifically, when the current of the second transistor T2 becomes large, the current of the first transistor T1 becomes large; when the current of the second transistor T2 becomes smaller, the current of the first transistor T1 becomes smaller.
Similarly, the fourth transistor T4 and the third transistor T3 also form a mirror connection.
Similarly, the fifth transistor T5 and the third transistor T3 also form a mirror connection.
T5, T6 and T7 form a first branch; t8, T9, T10 constitute a second branch.
The high-side oscillation circuit 110 supplies a high-frequency oscillation signal to the LC resonance circuit 120 as excitation. Specifically, as VDD voltage increases at circuit start-up, bias constant current sources Ibias1, ibias2, ibias3 and voltage bias VB in the system are established in advance.
As the VDD voltage further increases, the first and second branches are turned on. The operating points for the tubes T11 and T12, T3 and T4 are established successively. Specifically, T5, T6, T7 are diode series structures, and after being turned on at a suitable voltage, form a loop with the current source bias Ibias2, and the loop current flows through the diode structures to form a voltage drop, which provides bias for the base of T11, the bias voltage being approximately VDD-2V, so that the operating point of T11 is established.
Similarly, the diode structures formed by transistors T8, T9, T10 also start to provide voltage to the base of T12. At the initial start-up time, the base voltage of T12 and the base voltage of T11 are close to each other, and both are about VDD-2V.
Once T11 and T12 are properly biased, both tubes will conduct and both tube currents will flow into the T13 tube. As before, the T2 and T1 tubes form a current mirror, which copies the T1 tube current in proportion. When the base voltage of the T4 tube does not establish proper bias, the current of the T2 passes through the base of the T13 tube and flows into the resistor Radj through the emitter together with the collector current of the T13 tube. As the Radj voltage increases, the T4 tube base voltage builds up. Further, as the Radj voltage continues to increase, the T4 collector voltage is pulled low, causing the T13 tube base voltage to be pulled low, so that the T13 and T4 tubes form a negative feedback loop. When the base voltage of the T4 tube in the negative feedback loop is equal to the T3 tube base bias voltage VB, the negative feedback reaches equilibrium. Correspondingly, the voltage on Radj is VB, at least satisfying:
I Radj ＝VB/Radj；
wherein I is Radj Is the current flowing through resistor Radj. And the current is the sum of the T11 and T12 tube currents. It should be noted that the currents of the T11 tube and the T12 tube are not necessarily equal, and are determined by the relationship between the base voltages of the T11 tube and the T12 tube, and the currents of the two tubes are equal only when the base voltages are equal, and are I Radj Half of (a) is provided.
As can be seen from the above current formula, the T13 tube current is larger when the resistance Radj is smaller. Conversely, when the resistance Radj is large, the T13 tube current is small. The summary is: the T13 tube current is inversely proportional to the resistance Radj.
At the moment when the operating points of the respective parts of the system are initially established, the LC resonant circuit 120 starts to charge the resonant capacitor C through the T11 tube and the second branch, and it should be noted that, at the initial moment, the current of the T11 tube is I Radj And/2, and the second branch current is Ibias3, at least:
I total ＝I Radj /2+Ibias3。
wherein I is total Is the charging current of the resonant capacitor C.
Accordingly, the initial time when the charging current change rate is the largest can be understood as: the resonant coil L has the greatest inductive reactance at the moment and the resonant circuit exhibits an inductive character. Thus, as the charge of the resonant capacitor C increases, the voltage across C becomes gradually greater. Which in turn causes the base voltage of T12 to taper. In other words, the balance that the base electrodes of the original T12 and T11 are approximately equal is broken, so that the T12 current becomes smaller and the T11 current increases. It can be understood that: the charging current of the resonance capacitor C increases.
As the T11 tube current increases, it still further causes the T12 tube base voltage to decrease. Thus, the charging loop of the resonant capacitor C forms positive feedback, and the avalanche effect of the positive feedback accelerates the whole charging process.
When the base voltage of T12 is too small, resulting in T12 entering the linear region, the current of T11 is approximately equal to IRadj. Thus, at least:
Imax＝I Radj +Ibias3。
wherein Imax is the maximum charge current of the resonance capacitor C.
It should be noted that, as the positive feedback process advances, the base voltage of the T12 tube is forced to rise, which can be understood as that the potential of the T11 tube to the second connection line 102 is pulled down, and the T12 tube pushes up the second connection line 102, so as to form negative feedback.
When the charging current reaches a maximum value, correspondingly, the pull-down action of the T12 tube and the push-up action of the T12 tube reach balance. In this way, the rate of change of the charge current of the resonance capacitor C is 0. As the rate of change of current becomes smaller, the inductance of the resonant coil L becomes lowest, at which time the LC resonant circuit exhibits capacitance, and the resonant coil L completes energy storage.
When the resonance capacitance charging current change rate is 0, the resonance coil L may hinder such a change. In particular, the coil will convert the stored magnetic field energy into electric field energy to counteract this change.
With the release of the energy stored in the resonant coil L, the LC resonant circuit has a new freewheel path. Specifically, the resonance coil L converts the magnetic field energy into electric field energy, and transfers the electric charge stored in the resonance capacitor C to the VDD terminal. Therefore, the resonance capacitor C is in a discharge state.
As the discharging process proceeds, the voltage across the resonance capacitor C becomes gradually smaller. Correspondingly, the T11 collector voltage and the T12 base voltage gradually rise. When the base of T12 gradually increases to a certain voltage, the T12 tube starts to turn on again. In other words, conduction of the T12 tube results in a reduction in T11 tube current. Eventually at some point the T11 tube current is again equal to the T12 current. At this time, the voltage at the two ends of the resonant capacitor C falls to a minimum value, the energy stored in the resonant coil L is also depleted, and the circuit returns to the initial starting time state and enters a new oscillation cycle again.
In a specific embodiment, other circuits needed by the sensor circuit are also included for calculating the detection signal, providing the negative feedback control signal for the high-side oscillating circuit 110, and other circuits needed by the sensor for calibration, compensation, storage, setting, driving, protection, etc. The fourth transistor is connected as terminals at both ends for connecting the detection signal in the high-side oscillating circuit 110 to other circuits required for the sensor circuit on the one hand and for connecting the signal in the other circuits required for the sensor circuit to the high-side oscillating circuit 110 on the other hand.
The current of the second transistor T2 can be regarded as a current set of the first bias constant current source I1, the fifth transistor T5, and the fourth transistor T4.
When the circuit is started, the first bias constant current source I1 is started first. The first transistor replicates I1 and provides an initial excitation for LC tank circuit 120 through third transistor T3. At the same time, the fourth transistor T4 and the fifth transistor duplicate the current of the third transistor T3. Thus, the total current of the current set increases.
As the total current of the current set increases, the current of the second transistor T2 increases. Resulting in an increase in the current of the first transistor T1 and further in an increase in the total current of the current set, creating a positive feedback effect.
At the circuit start-up time, the positive feedback effect excites the LC resonant circuit 120, thereby realizing the rapid start-up of the LC resonant circuit and forming an excitation control circuit.
In one embodiment of the present invention, the excitation control circuit may further provide two transistors, the first transistor T1 and the second transistor T2, and when they are configured to have different sizes, the first transistor T1 may implement a scaled copy of the current of the second transistor T2.
Accordingly, since the third transistor T3 is mirror connected to the fourth transistor T4, the fourth transistor T4 can follow the third transistor T3 current in real time. And the third transistor T3 is connected to the LC resonance circuit 120 and serves as an excitation source of the LC resonance circuit 120. Therefore, the fourth transistor T4 can sense and follow the state characteristic of the LC resonant circuit 120 in real time, and send the sensed state characteristic to the operation circuit 420, so as to achieve the purpose of detecting the state of the LC resonant circuit 120, thereby forming a fusion detection circuit. The detection fusion circuit may further be configured to have two transistors, the third transistor T3 and the fourth transistor T4, and be configured to have different sizes, so that the compensation current of the LC resonance circuit 120 may be copied to the fourth transistor T4 in proportion to the third transistor T3 according to the state of the LC resonance circuit 120, thereby implementing state following and scaling detection of the LC resonance circuit 120.
In a specific embodiment, the fusion detection circuit includes a resistor Radj, as shown in fig. 2. The compensation current is received through a first resistor Radj. One end of the resistor Radj is connected with the emitter of the fourth transistor T4, the other end of the resistor Radj is grounded, and the compensation current is converted into compensation voltage through the resistor Radj.
The excitation control circuit provides excitation compensation for the LC resonant circuit as an excitation source, the excitation compensation forming a compensation current form on the third transistor T3 to characterize the resonant circuit state. And the compensation circuit is copied to scale by the fourth transistor T4. Thus, it can be converted into a compensation voltage at the first resistor Radj.
The compensation current value in the third transistor T3 follows the change at the same time throughout the change of the resonant circuit. The current of the fourth transistor T4 is thus proportionally varied and the compensation voltage across the resistor Radj is simultaneously varied. In other words, the amplitude of the compensation voltage characterizing the resonant circuit simultaneously follows the variation. The abstract "state change of the resonant circuit due to the approach of the external conductivity detector" is converted into an apparent compensation current change or compensation voltage change. The compensation current or the compensation voltage is also the variation of the excitation source on the excitation control circuit.
The resistor Radj can be reasonably selected according to the characteristics of the conductivity detector and the parameter configuration condition of the LC resonance circuit so as to achieve the optimal detection effect. The resistor Radj may be configured as a combination of a fixed resistor and a negative temperature coefficient resistor (PTC) to achieve uniformity of temperature characteristics of the overall circuit.
The fourth transistor T4 is sized n times (or, the mirror ratio is n) the third transistor T3, and n is 1 to 100, so as to improve the sensitivity to the state characteristics of the resonant circuit.
The sixth transistor T6 may be used as a negative feedback control tube to improve the stability of the circuit. Specifically, the negative feedback control tube T6 is connected to the fifth transistor T5, and the emitter of the negative feedback control tube T6 is grounded. Therefore, the base electrode of the negative feedback control tube T6 can carry out negative feedback control on the excitation detection fusion circuit through a negative feedback control signal provided by the negative feedback control circuit, so that the system state is stable.
As shown in fig. 3, the transistor may be replaced with a field effect transistor partially or completely.
The embodiment of the invention provides a high-side oscillating circuit of an inductive sensor, which can realize the driving of a resonant circuit at a high side. The problem that the requirement of high-side application cannot be met when the resonant circuit is arranged on the low side of the traditional inductive sensor is solved. Compared with the traditional oscillating circuit, the high-side oscillating circuit disclosed by the invention has a simple circuit topology structure, greatly reduces the complexity of the circuit structure and further reduces the cost. The circuit provided by the invention has few devices, has low requirement on device matching, reduces system power consumption, and improves the anti-interference performance of the circuit.
Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations are within the scope of the invention as defined by the appended claims.
Claims (8)
1. An inductive sensor high-side oscillating circuit, comprising:
one end of the excitation source module is connected with one output end of the current mirror module; the other end of the excitation source module is connected with a first bias constant current source; the control input end of the excitation source module is connected with a bias voltage source;
the two ports on one side of the negative feedback loop are connected with the excitation source module; two ports on the other side of the negative feedback loop are respectively connected with an LC resonance circuit and a detection resistor;
a pair of tube circuits, the input sides of which are connected with two ends of the LC resonance circuit; the output side of the pair of tube circuits is connected with one port of the negative feedback loop;
one end of the LC resonance circuit is connected with the current mirror module and the high-side voltage;
wherein, a transistor in the negative feedback loop and the excitation source module are in mirror image structures.
2. The inductive sensor high-side tank circuit of claim 1, wherein said current mirror module comprises:
the base electrode and the collector electrode of the first transistor T1 are in short circuit, and the emitter electrode of the first transistor T1 is connected with the high-side voltage;
a second transistor T2 having a base connected to the base of the first transistor T1; and the emitter of the second transistor is connected with the high-side voltage.
3. The inductive sensor high-side tank circuit of claim 2, wherein said excitation source module comprises:
a third transistor T3 having a base connected to the bias voltage source; the collector of the third transistor T3 is connected with the collector of the first transistor T1; an emitter of the third transistor T3 is connected to one end of the first bias constant current source Ibias 1; the other end of the first bias constant current source Ibias1 is grounded.
4. The inductive sensor high side tank circuit of claim 3, wherein said negative feedback loop comprises:
a fourth transistor T4 having a collector connected to the collector of the second transistor T2; an emitter of the fourth transistor T4 and an emitter of the third transistor T3 are commonly connected to one end of the first bias constant current source Ibias 1;
a thirteenth transistor T13 having a base connected to the collector of the fourth transistor T4; an emitter of the thirteenth transistor T13 is connected to a base of the fourth transistor T4; the emitter of the thirteenth transistor T13 is also grounded through the detection resistor Radj; the collector of the thirteenth transistor T13 is connected to the output of the pair of transistor circuits.
5. The inductive sensor high-side tank circuit of claim 4, wherein said pair of transistor circuits comprises:
an eleventh transistor T11 having a collector connected to the high-side voltage and one end of the LC resonant circuit; the base electrode of the eleventh transistor T11 is connected with the high-side voltage through a first branch circuit; an emitter of the eleventh transistor T11 is connected to a collector of the thirteenth transistor T13;
a twelfth transistor T12 having a collector connected to the other end of the LC resonant circuit; the base electrode of the twelfth transistor T12 is connected with the other end of the LC resonance circuit through a second branch; an emitter of the twelfth transistor T12 is connected to a collector of the thirteenth transistor T13.
6. The inductive sensor high-side tank circuit of claim 5, wherein said first branch comprises: a fifth transistor T5, a sixth transistor T6, and a seventh transistor T7; the second branch includes: an eighth transistor T8, a ninth transistor T9, and a tenth transistor T10;
wherein the bases of the fifth transistor T5, the sixth transistor T6, the seventh transistor T7, the eighth transistor T8, the ninth transistor T9 and the tenth transistor T10 are all in short circuit with the collectors thereof;
the collector of the fifth transistor T5 is connected with the high-side voltage; an emitter of the fifth transistor T5 is connected to a collector of the sixth transistor T6; an emitter of the sixth transistor T6 is connected to a collector of the seventh transistor T7; an emitter of the seventh transistor T7 is connected to a base of the eleventh transistor T11;
a collector of the eighth transistor T8 is connected to the other end of the LC resonant circuit and a collector of the eleventh transistor T11; an emitter of the eighth transistor T8 is connected to a collector of the ninth transistor T9; an emitter of the ninth transistor T9 is connected to a collector of the tenth transistor T10; an emitter of the tenth transistor T10 is connected to a base of the twelfth transistor T12.
7. The inductive sensor high-side tank circuit of claim 6, further comprising:
a second bias constant current source Ibias2, one end of which is connected with the emitter of the seventh transistor T7, and the other end of the second bias constant current source Ibias2 is grounded;
and one end of the third bias constant current source Ibias3 is connected with the bases of the tenth transistor T10 and the twelfth transistor T12, and the other end of the third bias constant current source Ibias3 is grounded.
8. The inductive sensor high-side tank circuit of claim 4, further comprising:
an arithmetic circuit for collecting and calculating a detection signal through the emitter and/or the base of the fourth transistor T4; the arithmetic circuit also connects a negative feedback control signal to the high-side oscillating circuit through the collector and/or emitter of the fourth transistor T4.
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| US4581593A (en) * | 1983-05-25 | 1986-04-08 | Sony Corporation | Variable frequency oscillating circuit |
| JPS63257313A (en) * | 1987-04-15 | 1988-10-25 | Hitachi Ltd | Input negative resistance compensation circuit |
| US4870383A (en) * | 1987-12-30 | 1989-09-26 | U.S. Philips Corporation | Oscillator circuit |
| JPH02202104A (en) * | 1989-01-30 | 1990-08-10 | Nec Ic Microcomput Syst Ltd | Oscillation circuit |
| CN1356772A (en) * | 2000-02-10 | 2002-07-03 | 松下电器产业株式会社 | Oscillator circuit |
| CN107276538A (en) * | 2017-05-27 | 2017-10-20 | 珠海市杰理科技股份有限公司 | RF voltage-controlled oscillator |
| CN113489460A (en) * | 2021-07-02 | 2021-10-08 | 珠海市杰理科技股份有限公司 | RC oscillation circuit and RC oscillator |
-
2023
- 2023-12-18 CN CN202311739453.1A patent/CN117713693B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4581593A (en) * | 1983-05-25 | 1986-04-08 | Sony Corporation | Variable frequency oscillating circuit |
| JPS63257313A (en) * | 1987-04-15 | 1988-10-25 | Hitachi Ltd | Input negative resistance compensation circuit |
| US4870383A (en) * | 1987-12-30 | 1989-09-26 | U.S. Philips Corporation | Oscillator circuit |
| JPH02202104A (en) * | 1989-01-30 | 1990-08-10 | Nec Ic Microcomput Syst Ltd | Oscillation circuit |
| CN1356772A (en) * | 2000-02-10 | 2002-07-03 | 松下电器产业株式会社 | Oscillator circuit |
| CN107276538A (en) * | 2017-05-27 | 2017-10-20 | 珠海市杰理科技股份有限公司 | RF voltage-controlled oscillator |
| CN113489460A (en) * | 2021-07-02 | 2021-10-08 | 珠海市杰理科技股份有限公司 | RC oscillation circuit and RC oscillator |
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| CN117713693B (en) | 2024-08-27 |
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