Boost type adjustable high-voltage reference source

Abstract

The invention relates to a boost type adjustable high-voltage reference source which comprises a Boost topological structure, a voltage doubling circuit and an output filter circuit. The Boost topological structure comprises an LC circuit, a switching circuit and a voltage feedback circuit; the LC circuit receives external input voltage, when the switching circuit is closed, the external input voltage flows through the inductor, and the inductor stores energy; when the switching circuit is disconnected, the inductor discharges to charge the LC circuit and the capacitor in the voltage doubling circuit, and the voltage at the two ends of the capacitor is increased, so that the output voltage is higher than the input voltage; the voltage doubling circuit reduces the voltage-withstanding requirement on the device through a multi-stage structure, and the output voltage is sent to the output filter circuit to be filtered and then output; and the voltage feedback circuit samples the output voltage of the voltage doubling circuit, compares the output voltage with the reference voltage, controls the on-off time of the switching circuit, and realizes closed-loop control of the output voltage. The problem that high reference voltage is generated under the condition of low power supply voltage is solved, circuit miniaturization and low power consumption are achieved through the Boost topological structure, and the requirement for device performance is lowered through the voltage doubling circuit.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit design and relates to a boosted adjustable high-voltage reference source. Background Art

[0002] In the micro-capacitor detection circuit, it is necessary to apply a high voltage on one side of the capacitor to achieve high-precision detection. Figure 1 Take the micro-capacitor detection circuit shown in the figure as an example, the output voltage is proportional to the input capacitance C in The expression of the relationship is:

[0003]

[0004] It can be seen from the expression that the reference voltage HV is not only related to the capacitance detection sensitivity, but also that increasing the reference voltage can effectively improve the capacitance detection sensitivity. At the same time, the stability of the reference voltage also determines the stability of the capacitance detection result. o Output of the micro-capacitance detection circuit.

[0005] In terms of electrostatic drive of capacitors, high reference voltage also plays an important role. In the case of AC drive, the electrostatic force expression is:

[0006]

[0007] Where HV is the reference voltage, Vin is the electrostatic drive voltage, C is the capacitance value, ω is the signal frequency, t is the time, and d is the capacitor spacing. It can be seen from the expression that increasing the reference voltage HV can improve the electrostatic drive efficiency, and the stability of the reference voltage also determines the stability of the electrostatic drive.

[0008] Through the analysis of the above application scenarios, we can see that high-stability high-voltage reference sources are of great significance for improving the performance of capacitor products. However, most of the commonly used high-voltage reference source solutions are step-down reference sources, which only stabilize the output voltage under high-voltage input conditions and cannot provide a reference voltage that exceeds the input voltage value.

[0009] The normal operation of the capacitance detection or capacitance electrostatic drive circuit requires a high voltage reference to improve the detection sensitivity and the driving efficiency of the electrostatic force. The power supply voltage of electronic products usually does not exceed 15V, so the ideal way is to obtain a high voltage reference source through a boost circuit. For the boost type reference voltage source, there are currently no integrated circuits or unit circuits available. However, the traditional boost power supply circuit has not been designed for the application characteristics of extremely light load, extremely high stability and extremely high boost ratio in the application of high voltage reference source. Most of them have problems such as large size, high static power consumption and high requirements on component performance, which are not suitable for the application of capacitance detection or capacitance electrostatic drive circuit. Therefore, it is urgent to develop a boost type adjustable high voltage reference source to achieve a small size, low power consumption, high stability high voltage reference source to meet the application requirements of various types of capacitance detection or capacitance electrostatic drive circuits. Summary of the invention

[0010] The technical problem solved by the invention is to overcome the deficiencies of the prior art and provide a boost type adjustable high voltage reference source.

[0011] The solution of the present invention is:

[0012] A boost type adjustable high voltage reference source, comprising a Boost topology structure, a voltage doubling circuit and an output filter circuit; the Boost topology structure comprises an LC circuit, a switch circuit and a voltage feedback circuit;

[0013] The switch circuit is closed or opened under the control of the voltage feedback circuit;

[0014] The LC circuit receives an external input voltage. When the switch circuit is closed, the external input current flows through the inductor, and the inductor current increases linearly at a certain ratio, thereby storing energy. When the switch circuit is disconnected, the inductor begins to discharge, that is, charging the capacitors of the LC circuit and the voltage doubler circuit. The voltage across the capacitor increases and is higher than the input voltage, completing the voltage boost.

[0015] The voltage doubler circuit reduces the voltage resistance requirement of the device through a multi-stage structure, and the final output voltage is sent to the output filter circuit;

[0016] The voltage feedback circuit samples the output voltage of the voltage doubler circuit and compares it with the reference voltage, controls the on-off time of the switch circuit, and realizes closed-loop control and accurate regulation of the output voltage;

[0017] The output filter circuit filters the received voltage and then outputs it.

[0018] Preferably, the voltage doubling circuit is a single-stage voltage doubling structure or a multi-stage voltage doubling structure.

[0019] Preferably, in the Boost topology, the LC circuit includes an inductor L 11 、Diode D 11and capacitor C out12 The voltage doubler circuit adopts a first-stage voltage doubler structure, including a diode D 12 , D 13 , capacitor C out11 , C 11 ;

[0020] Inductance L 11 One end is connected to the external input voltage V IN , the other end is connected to diode D 11 The positive electrode, one end of the switch circuit and the capacitor C 11 One end of the diode D 11 The negative electrode of the capacitor C out12 One end of the diode D 12 The positive electrode of capacitor C out12 The other end of the capacitor C 11 The other end is connected to the diode D 12 The cathode of diode D 13 The positive pole of diode D 13 The negative electrode of the capacitor C out11 The other input end of the voltage feedback circuit is connected to the reference voltage, and the capacitor C out11 The other end of the diode D 11 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit.

[0021] Preferably, the voltage feedback circuit is implemented using a voltage comparator.

[0022] Preferably, the switch circuit is implemented by using controllable on / off components. When the voltage feedback circuit is from the diode D 13 When the voltage sampled from the negative electrode of is higher than the reference voltage, the voltage feedback circuit controls the switch circuit to close; when the voltage feedback circuit controls the switch circuit to close from the diode D 13 When the voltage sampled at the negative electrode is lower than the reference voltage, the voltage feedback circuit controls the switch circuit to be disconnected.

[0023] Preferably, the output filter circuit includes an inductor R f1 and capacitor C f1 , inductor R f1 One end of the diode D 13 The negative connection of the inductor R f1 The other end of the capacitor C f1 Ground.

[0024] Preferably, in the Boost topology, the LC circuit includes an inductor L 21 、Diode D 21and capacitor C out23 The voltage doubling circuit adopts a two-stage voltage doubling structure, and the two-stage voltage doubling structure includes a first-stage voltage doubling structure and a second-stage voltage doubling structure;

[0025] The first stage voltage doubling structure includes diode D 22 , D 23 , capacitor C out22 , C 21 ; The second stage voltage doubling structure includes diode D 24 , D 25 , capacitor C out21 , C 22 ;

[0026] Inductance L 21 One end is connected to the external input voltage V IN , the other end is connected to diode D 21 The positive electrode, one end of the switch circuit and the capacitor C 21 One end of the diode D 21 The negative electrode of the capacitor C out23 One end of the diode D 22 The positive electrode of capacitor C out23 The other end of the capacitor C 21 The other end is connected to the diode D 22 The cathode of diode D 23 The positive electrode and capacitor C 22 One end of the diode D 23 The cathode of the diode D 24 The positive electrode and capacitor C out22 One end of the capacitor C out22 The other end of the diode D 21 The negative electrode of capacitor C 22 The other end is connected to the diode D 24 The cathode of diode D 25 The positive pole of diode D 25 The negative electrode of the capacitor C out21 The input end of the output filter circuit and the input end of the voltage feedback circuit, capacitor C out21 The other end of the diode D 23 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit.

[0027] Preferably, the voltage feedback circuit is implemented using a PWM controller.

[0028] Preferably, the switch circuit is implemented by using components with controllable on and off, and the PWM controller is from the diode D 25The negative electrode sampling voltage is compared with its internal low voltage reference source. The comparator inside the PWM controller generates a PWM control signal based on the comparison result to control the switch K 21 The on and off.

[0029] Preferably, the output filter circuit includes an inductor R f2 and capacitor C f2 , inductor R f2 One end of the diode D 25 The negative connection of the inductor R f2 The other end of the capacitor C f2 Ground.

[0030] The beneficial effects of the present invention compared with the prior art are:

[0031] The present invention solves the problem of generating a high reference voltage under a low power supply voltage condition, realizes circuit miniaturization and low power consumption by utilizing a Boost topology structure, and reduces the requirement for device performance by utilizing a voltage doubling circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of a micro-capacitance detection circuit based on transimpedance amplification;

[0033] Figure 2 The schematic diagram of the circuit structure of the present invention;

[0034] Figure 3 It is a schematic diagram of an adjustable high-voltage reference source with a first-stage voltage multiplication structure;

[0035] Figure 4 Schematic diagram of an adjustable high-voltage reference source with a two-stage voltage multiplication structure. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] According to the application characteristics of high-voltage reference in micro-capacitor detection or driving schemes, the present invention proposes a boost-type adjustable high-voltage reference source scheme based on Boost+voltage doubling+low-pass filtering, and uses the Boost topology structure to achieve voltage boosting with as few components as possible; uses a single-stage / multi-stage voltage doubling circuit to reduce the requirements on component performance under high boost ratio conditions; and uses the characteristics of capacitive loads to adopt low-pass filtering to effectively suppress switching noise.

[0038] The circuit structure of the present invention is as follows Figure 2As shown in the figure, it includes three main parts: Boost topology, voltage doubling circuit and output filter circuit. Boost topology mainly consists of LC circuit, switch circuit and voltage feedback circuit. LC circuit uses the freewheeling characteristics of inductor to charge capacitor, so as to achieve voltage boost. The core components are inductor, capacitor and diode to prevent current reverse. The switch circuit is used to control the working state of inductor and capacitor. When the switch is closed, the input voltage flows through the inductor, and the inductor current increases linearly at a certain proportion, so as to store energy; when the switch is disconnected, due to the current holding characteristics of the inductor, the inductor starts to discharge, that is, charging the capacitor, and the voltage across the capacitor increases and is higher than the input voltage, thus completing the boost function. The voltage feedback circuit samples the output voltage and compares it with the reference voltage to control the on-off time of the switch circuit, thereby forming a closed-loop control and accurate regulation of the output voltage. In order to reduce the dependence on component performance when high voltage output is used, a voltage doubling circuit composed of capacitors and diodes is added after the Boost topology structure to enable a single inductor to charge multiple series capacitors. At this time, the output voltage will be evenly distributed on multiple series capacitors, thereby effectively reducing the requirements for device withstand voltage. The number of voltage doubling circuits needs to be considered comprehensively based on output voltage, device performance, circuit volume, and power consumption. In order to improve the noise performance of the high-voltage reference source, the load can take advantage of the low requirements for the output impedance of the previous stage, and a series low-pass filter can be used to improve the suppression effect of high-frequency noise.

[0039] Example 1

[0040] Figure 3 A high voltage reference source implementation scheme is given. At this time, the voltage doubler circuit is a one-stage voltage doubler structure.

[0041] In the Boost topology, the LC circuit includes the inductor L 11 、Diode D 11 and capacitor C out12 The voltage doubler circuit adopts a first-stage voltage doubler structure, including a diode D 12 , D 13 , capacitor C out11 , C 11 .

[0042] Inductance L 11 One end is connected to the external input voltage V IN , the other end is connected to diode D 11 The positive electrode, one end of the switch circuit and the capacitor C 11 One end of the diode D 11 The negative electrode of the capacitor C out12 One end of the diode D 12 The positive electrode of capacitor C out12 The other end of the capacitor C 11The other end is connected to the diode D 12 The cathode of diode D 13 The positive pole of diode D 13 The negative electrode of the capacitor C out11 The other input end of the voltage feedback circuit is connected to the reference voltage, and the capacitor C out11 The other end of the diode D 11 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit. The voltage feedback circuit is implemented using a voltage comparator. The switch circuit is implemented using components with controllable on and off. When the voltage feedback circuit is connected from the diode D 13 When the voltage sampled from the negative electrode of is higher than the reference voltage, the voltage feedback circuit controls the switch circuit to close; when the voltage feedback circuit controls the switch circuit to close from the diode D 13 When the voltage sampled at the negative electrode is lower than the reference voltage, the voltage feedback circuit controls the switch circuit to disconnect. The output filter circuit includes an inductor R f1 and capacitor C f1 , inductor R f1 One end of the diode D 13 The negative connection of the inductor R f1 The other end of the capacitor C f1 Ground.

[0043] Switching circuit K 11 It is used to control the working state of the inductor. It can be realized by using MOS tube or triode, or other devices with switching characteristics. 11 When closed, the power supply V IN Supply power to the inductor, and the current through the inductor gradually increases; when K 11 When disconnected, the inductor continues to flow through the diode D 11 , D 12 and D 13 To capacitor C out11 and C out12 The diode D 11 , D 12 and capacitor C out11 Together they form a voltage doubling circuit, thereby reducing the requirements for circuit device performance. The output of the voltage doubling circuit is stepped down by the voltage sampling circuit and then compared with the low voltage reference source by the voltage comparator to control K 11The on-off of the output voltage is realized to realize the closed-loop control of the output voltage. The voltage sampling circuit can be composed of a resistor network, and the linear adjustment of the output voltage can be realized by adjusting the resistor ratio. In order to suppress high-frequency noise, the high-voltage reference source needs to be filtered before output. The filter can choose the classic RC filter or LC filter, or other filter networks can be used. The filter design needs to be adjusted according to the load conditions.

[0044] Example 2

[0045] Figure 4 A scheme for implementing a high voltage reference source based on a PWM controller is given. In this case, the voltage doubling circuit is a two-stage voltage doubling structure.

[0046] In the Boost topology, the LC circuit includes the inductor L 21 、Diode D 21 and capacitor C out23 The voltage doubling circuit adopts a two-stage voltage doubling structure, which includes a first-stage voltage doubling structure and a second-stage voltage doubling structure. The first-stage voltage doubling structure includes a diode D 22 , D 23 , capacitor C out22 , C 21 ; The second stage voltage doubling structure includes diode D 24 , D 25 , capacitor C out21 , C 22 .

[0047] Inductance L 21 One end is connected to the external input voltage V IN , the other end is connected to diode D 21 The positive electrode, one end of the switch circuit and the capacitor C 21 One end of the diode D 21 The negative electrode of the capacitor C out23 One end of the diode D 22 The positive electrode of capacitor C out23 The other end of the capacitor C 21 The other end is connected to the diode D 22 The cathode of diode D 23 The positive electrode and capacitor C 22 One end of the diode D 23 The cathode of the diode D 24 The positive electrode and capacitor C out22 One end of the capacitor C out22 The other end of the diode D 21 The negative electrode of capacitor C 22 The other end is connected to the diode D 24 The cathode of diode D 25The positive pole of diode D 25 The negative electrode of the capacitor C out21 The input end of the output filter circuit and the input end of the voltage feedback circuit, capacitor C out21 The other end of the diode D 23 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit. The voltage feedback circuit is implemented using a PWM controller.

[0048] The switch circuit is implemented with controllable on / off components. The PWM controller starts from the diode D 25 The negative electrode sampling voltage is compared with its internal low voltage reference source. The comparator inside the PWM controller generates a PWM control signal based on the comparison result to control the switch K 21 On / Off

[0049] The output filter circuit includes an inductor R f2 and capacitor C f2 , inductor R f2 One end of the diode D 25 The negative connection of the inductor R f2 The other end of the capacitor C f2 Ground.

[0050] Figure 4 In order to further increase the output voltage, the circuit adopts a two-stage voltage doubling scheme, in which the diode D 24 , D 25 and capacitor C out21 Together they form a secondary voltage doubling circuit; the output voltage collected by the voltage sampling circuit is passed through a dedicated PWM controller (such as UC1843) to generate a PWM signal to control K 21 Switching circuit K 21 It is used to control the working state of the inductor. It can be realized by using MOS tube or triode, or other devices with switching characteristics. In order to improve the load capacity of the high-voltage reference source, the filter adopts an inductor L f2 and capacitor C f2 The LC filtering solution is composed of

[0051] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A boost type adjustable high voltage reference source, characterized in that: It includes Boost topology structure, voltage doubling circuit and output filter circuit; Boost topology structure includes LC circuit, switch circuit and voltage feedback circuit; The switch circuit is closed or opened under the control of the voltage feedback circuit; The LC circuit receives an external input voltage. When the switch circuit is closed, the external input current flows through the inductor, and the inductor current increases linearly at a certain ratio, thereby storing energy. When the switch circuit is disconnected, the inductor begins to discharge, that is, charging the capacitors of the LC circuit and the voltage doubler circuit. The voltage across the capacitor increases and is higher than the input voltage, completing the voltage boost. The voltage doubler circuit reduces the voltage resistance requirement of the device through a multi-stage structure, and the final output voltage is sent to the output filter circuit; The voltage feedback circuit samples the output voltage of the voltage doubler circuit and compares it with the reference voltage, controls the on-off time of the switch circuit, and realizes closed-loop control and accurate regulation of the output voltage; The output filter circuit filters the received voltage and then outputs it.

2. A boost type adjustable high voltage reference source according to claim 1, characterized in that: The voltage doubler circuit is a single-stage voltage doubler structure or a multi-stage voltage doubler structure.

3. The step-up adjustable high voltage reference source according to claim 1, characterized in that: In the Boost topology, the LC circuit includes the inductor L 11 、Diode D 11 and capacitor C out12 The voltage doubler circuit adopts a first-stage voltage doubler structure, including a diode D 12 , D 13 , capacitor C out11 , C 11 ; Inductance L 11 One end is connected to the external input voltage V IN , the other end is connected to diode D 11 The positive electrode, one end of the switch circuit and the capacitor C 11 One end of the diode D 11 The negative electrode of the capacitor C out12 One end of the diode D 12 The positive electrode of capacitor C out12 The other end of the capacitor C 11 The other end is connected to the diode D 12 The cathode of diode D 13 The positive pole of diode D 13 The negative electrode of the capacitor C out11 The other input end of the voltage feedback circuit is connected to the reference voltage, and the capacitor C out11 The other end of the diode D 11 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit.

4. The step-up adjustable high voltage reference source according to claim 3, characterized in that: The voltage feedback circuit is implemented using a voltage comparator.

5. The step-up adjustable high voltage reference source according to claim 3, characterized in that: The switch circuit is realized by using controllable on-off components. When the voltage feedback circuit is from the diode D 13 When the voltage sampled from the negative electrode of is higher than the reference voltage, the voltage feedback circuit controls the switch circuit to close; when the voltage feedback circuit is connected from the diode D 13 When the voltage sampled at the negative electrode is lower than the reference voltage, the voltage feedback circuit controls the switch circuit to be disconnected.

6. The step-up adjustable high voltage reference source according to claim 3, characterized in that: The output filter circuit includes an inductor R f1 and capacitor C f1 , inductor R f1 One end of the diode D 13 The negative connection of the inductor R f1 The other end of the capacitor C f1 Ground.

7. The step-up adjustable high voltage reference source according to claim 1, characterized in that: In the Boost topology, the LC circuit includes the inductor L 21 、Diode D 21 and capacitor C out23 The voltage doubling circuit adopts a two-stage voltage doubling structure, and the two-stage voltage doubling structure includes a first-stage voltage doubling structure and a second-stage voltage doubling structure; The first stage voltage doubling structure includes diode D 22 , D 23 , capacitor C out22 , C 21 ; The second stage voltage doubling structure includes diode D 24 , D 25 , capacitor C out21 , C 22 ; Inductance L 21 One end is connected to the external input voltage V IN , the other end is connected to diode D 21 The positive electrode, one end of the switch circuit and the capacitor C 21 One end of the diode D 21 The negative electrode of the capacitor C out23 One end of the diode D 22 The positive electrode of capacitor C out23 The other end of the capacitor C 21 The other end is connected to the diode D 22 The cathode of diode D 23 The positive electrode and capacitor C 22 One end of the diode D 23 The cathode of the diode D 24 The positive electrode and capacitor C out22 One end of the capacitor C out22 The other end of the diode D 21 The negative electrode of capacitor C 22 The other end is connected to the diode D 24 The cathode of diode D 25 The positive pole of diode D 25 The negative electrode of the capacitor C out21 The input end of the output filter circuit and the input end of the voltage feedback circuit, capacitor C out21 The other end of the diode D 23 The other end of the switch circuit is grounded, and the control end of the switch circuit is connected to the output end of the voltage feedback circuit.

8. The step-up adjustable high voltage reference source according to claim 7, characterized in that: The voltage feedback circuit is implemented using a PWM controller.

9. The step-up adjustable high voltage reference source according to claim 8, characterized in that: The switch circuit is implemented with controllable on / off components. The PWM controller starts from the diode D 25 The negative electrode sampling voltage is compared with its internal low voltage reference source. The comparator inside the PWM controller generates a PWM control signal based on the comparison result to control the switch K 21 The on and off.

10. The step-up adjustable high voltage reference source according to claim 7, characterized in that: The output filter circuit includes an inductor R f2 and capacitor C f2 , inductor R f2 One end of the diode D 25 The negative connection of the inductor R f2 The other end of the capacitor C f2 Ground.

Images