Aerosol-forming device

Abstract

The utility model discloses an aerosol forming device, the aerosol forming device comprises a microwave generation module and a microwave amplification module, the microwave amplification module comprises a power amplifier and a filter, the power amplifier is used for performing power amplification on microwave signals generated by the microwave generation module, and the filter is connected with the output end of the power amplifier. The filter comprises a plurality of filtering units used for suppressing different subharmonic signals respectively, each filtering unit comprises a filtering microstrip line and a filtering capacitor, the filtering microstrip lines in the filtering units are sequentially connected end to end to form an output end microstrip line, and the output end microstrip line is connected with the filtering capacitor. And the filter capacitor in each filter unit is connected between the output end of the filter microstrip line and the ground. According to the technical scheme, the additional efficiency of the power amplifier can be improved, and the power amplifier is smaller in size and lower in cost.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of microwave heating, especially to an aerosol forming device. BACKGROUND

[0002] In microwave communication products, power amplifiers (PA) are needed to amplify microwave signals. In order to take into account the linearity, distortion and signal-to-noise ratio of microwave signals, the gain of the power amplifier is designed to be certain back-off, resulting in that the power amplifier additional efficiency (PAE) is not in the highest state, and is generally only about 50%. However, in microwave heating products, the power amplifier is a key component for energy conversion and output, and the maximization of the additional efficiency is pursued, and other indicators are generally not considered. Therefore, in microwave heating products, the design of the power amplifier cannot directly use the design case of microwave communication products as a reference, and the microstrip circuit matched with the input / output end of the power amplifier needs to be redesigned.

[0003] In microwave heating products, the suppression of out-of-band harmonics is a method to improve the additional efficiency of the power amplifier. In order to suppress out-of-band harmonics, a microstrip circuit branch, a cavity filter or other filter devices are generally connected to the output end of the power amplifier. However, the connection of the microstrip circuit branch will introduce additional insertion loss and increase the circuit area, which is not conducive to the design of product miniaturization; although the cavity filter has small insertion loss, it will bring the problems of large size and high cost. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an aerosol forming device to solve the technical defects of low efficiency, large area, large volume and high cost in the prior art.

[0005] The technical solution adopted by the present application to solve the technical problem is: an aerosol forming device is constructed, which comprises a microwave generating module and a microwave amplifying module. The microwave amplifying module comprises a power amplifier for power amplifying the input microwave signal and a filter connected to the output end of the power amplifier. The filter comprises a plurality of filter units for suppressing different harmonic signals. Each filter unit comprises a filter microstrip line and a filter capacitor. The filter microstrip lines in each filter unit are connected in sequence and end to end to form an output microstrip line. The filter capacitor in each filter unit is connected between the output end of the filter microstrip line and the ground.

[0006] Optionally, the number of filter units is three, four or five.

[0007] Optionally, it further comprises an input microstrip line connected to the input end of the power amplifier, and the width of the input microstrip line increases in steps, and the width of the output microstrip line decreases in steps.

[0008] Optionally, the number of filter units is four, and the width of the filter microstrip line of the first two filter units is 2-3mm, and the width of the filter microstrip line of the last two filter units is 0.8-1.2mm.

[0009] Optionally, the input end microstrip line comprises a first microstrip line and a second microstrip line connected in series, the width of the first microstrip line is 0.8-1.2mm, and the width of the second microstrip line is 1-2.5mm.

[0010] Optionally, the microwave amplification module further comprises a feeding unit, the feeding unit comprises a feeding microstrip line and a decoupling capacitor, wherein the first end of the feeding microstrip line is connected to the output end of the power amplifier, the second end of the feeding microstrip line is connected to a direct current power supply, the first end of the decoupling capacitor is connected to the second end of the second microstrip line, the second end of the decoupling capacitor is grounded, and the length of the feeding microstrip line is related to 1 / 4 of the wavelength of the fundamental wave of the microwave signal.

[0011] Optionally, the feeding unit further comprises a power supply microstrip line with an impedance of 50 ohms, and the power supply microstrip line is connected between the second end of the feeding microstrip line and the direct current power supply.

[0012] Optionally, the microwave amplification module further comprises:

[0013] an output coupling capacitor connected to the output end microstrip line; and / or,

[0014] an input coupling capacitor connected to the input end microstrip line.

[0015] Optionally, the output coupling capacitor is arranged at the rear section of the output end microstrip line; and / or,

[0016] the input coupling capacitor is arranged at the front section of the input end microstrip line.

[0017] Optionally, the microwave amplification module further comprises a dielectric layer and a ground layer arranged below the input end microstrip line and the output end microstrip line, respectively. Through the technical solution of the present application, an equivalent low-pass low-resistance multi-stage filter is formed at the output end of the power amplifier by arranging capacitors with appropriate parameters at different length positions of the output end microstrip line, which can effectively suppress out-of-band harmonics and improve the additional efficiency of the power amplifier. In addition, compared with existing microstrip circuit stubs, cavity filters and other filter devices, the size and volume are smaller, meeting the design trend of product miniaturization, and the circuit cost is lower. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to illustrate the embodiments of the present application more clearly, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some of the embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings. The drawings are as follows:

[0019] Figure 1 is a circuit diagram of a microwave amplification module of an aerosol forming device in an embodiment of the present application;

[0020] Figure 2 is a physical diagram of a microwave amplification module of an aerosol forming device in an embodiment of the present application;

[0021] Figure 3 is a schematic diagram of a microstrip line laid on a PCB in an embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0023] The aerosol forming device of the present application comprises a microwave generation module and a microwave amplification module, wherein the microwave generation module is used to generate a microwave signal, and the microwave amplification module is used to amplify the microwave signal generated by the microwave generation module. In combination with Figure 1 and Figure 2 In an embodiment, the microwave amplification module comprises a power amplifier 10 and a filter 20, wherein the power amplifier 10 performs power amplification on the input microwave signal, and the frequency band of the input microwave signal (i.e. the working signal of the power amplifier 10) is for example 2.4G-2.5GHz; the filter 20 is connected with the output end of the power amplifier 10 and is used to suppress the out-of-band harmonic.

[0024] The filter 20 comprises four filter units respectively used to suppress different harmonic signals. Each filter unit comprises a filter microstrip line and a filter capacitor, and the filter microstrip lines in each filter unit are connected in sequence in a head-to-tail manner to form an output end microstrip line, and the filter capacitor in each filter unit is connected between the output end of the filter microstrip line and the ground. Specifically, in combination with Figure 1 and Figure 2The first filter unit comprises a filter microstrip line MSL5 and a filter capacitor C2, the second filter unit comprises a filter microstrip line MSL6 and a filter capacitor C3, the third filter unit comprises a filter microstrip line MSL7 and a filter capacitor C4, and the fourth filter unit comprises a filter microstrip line MSL8, a filter microstrip line MSL9 (the filter microstrip lines MSL8 and MSL9 can be equivalent to a microstrip line), and a filter capacitor C6. Furthermore, the filter microstrip lines MSL5, MSL6, MSL7, MSL8, and MSL9 are connected in sequence and end to end to form an output microstrip line. The filter capacitor C2 is connected between the output of the filter microstrip line MSL5 and the ground, the filter capacitor C3 is connected between the output of the filter microstrip line MSL6 and the ground, the filter capacitor C4 is connected between the output of the filter microstrip line MSL7 and the ground, and the filter capacitor C6 is connected between the output of the filter microstrip line MSL9 and the ground.

[0025] In addition, in each filter unit, the length of the filter microstrip line and the capacitance of the filter capacitor are related to the frequency of the harmonic signal to be suppressed by the corresponding filter unit. Specifically, the length of the filter microstrip line MSL5 and the capacitance of the filter capacitor C2 are related to the frequency of the first harmonic signal of the working signal (for example, 4.8-5 GHz). For example, the length of the filter microstrip line MSL5 is 1.0-2.0 mm, the filter capacitor C2 is a high-Q capacitor with a capacitance of 0.5-4.0 pF, and is connected between the output of the filter microstrip line MSL5 and the ground, which is equivalent to the first-order LC low-pass filter unit with the filter microstrip line MSL5. The length of the filter microstrip line MSL6 and the capacitance of the filter capacitor C3 are related to the frequency of the second harmonic signal of the working signal. For example, the length of the filter microstrip line MSL6 is 4.0-6.0 mm, the filter capacitor C3 is a high-Q capacitor with a capacitance of 0.5-4.0 pF, and is connected between the output of the filter microstrip line MSL6 and the ground, which is equivalent to the second-order LC low-pass filter unit with the filter microstrip line MSL6. The length of the filter microstrip line MSL7 and the capacitance of the filter capacitor C4 are related to the frequency of the third harmonic signal of the working signal. For example, the length of the filter microstrip line MSL7 is 2.0-3.0 mm, the filter capacitor C4 is a high-Q capacitor with a capacitance of 0.5-4.0 pF, and is connected between the output of the filter microstrip line MSL7 and the ground, which is equivalent to the third-order LC low-pass filter unit with the filter microstrip line MSL7. The length of the filter microstrip lines MSL8 and MSL9 and the capacitance of the filter capacitor C6 are related to the frequency of the fourth harmonic signal of the working signal. For example, the total length of the filter microstrip lines MSL8 and MSL9 is 4.0-6.0 mm, the filter capacitor C6 is a capacitor with a capacitance of 0.2-1.0 pF, and is connected between the output of the filter microstrip line MSL9 and the ground, which is equivalent to the fourth-order LC low-pass filter unit with the filter microstrip lines MSL8 and MSL9.

[0026] As to this embodiment, it is to be noted that each filter unit is an equivalent LC low-pass filter unit, and the four filter units constitute a four-order low-pass filter. It should be understood that although this embodiment shows a four-order filter, in other embodiments, the order of the filter can also be other numbers, for example, three, five, etc. Correspondingly, the number of filter units can also be three, five, etc. It is also to be noted that theoretically, the higher the order of the filter, the higher the suppression of the harmonic order, and the higher the efficiency of the microwave amplification module. However, in practical applications, since the harmonic energy is mainly concentrated in the low-order harmonics, the energy of the high-order harmonics (for example, above the 6th order) is small, and if the number of filter units is too large, it will also increase the volume and cost of the microwave amplification module, therefore, the number of filter units can be selected to be three, four, five, and preferably four. In addition, since each order of filter unit itself has energy loss, when more filter units are set, when higher order harmonics are suppressed, the loss of the corresponding filter unit itself can exceed the energy of the high-order harmonics, so more filter units do not play a role in improving efficiency.

[0027] Further, in this embodiment, the width of the output end microstrip line (for example, MSL5, MSL6, MSL7, MSL8, MSL9 connected in sequence from head to tail) decreases in a stepped manner. In addition, the microwave amplification module of this embodiment also includes an input end microstrip line connected to the input end of the power amplifier 10, and the width of the input end microstrip line increases in a stepped manner. As to this embodiment, first of all, it is to be noted that since the internal impedance of the power amplifier (for example, 8.5+j*27.486 ohms) is smaller than the external line impedance (50 ohms), when designing the microwave amplification module, impedance matching needs to be performed on the input end and the output end of the power amplifier. Moreover, since the impedance of the microstrip line is mainly related to its width, of course, it is also related to its thickness, the thickness of the line and the ground medium, and the dielectric constant of the dielectric medium, therefore, when the thickness of the microstrip line, the thickness of the line and the ground medium, and the dielectric constant of the dielectric medium are determined, the closer to the power amplifier, the larger the width of the microstrip line, and the closer to the internal impedance of the power amplifier; the farther away from the power amplifier, the smaller the width of the microstrip line, and the closer to the external line impedance. Therefore, such width stepped change of the input end microstrip line and the output end microstrip line can reduce the power loss of the microwave signal, and further improve the additional efficiency of the power amplifier.

[0028] In addition, it is to be noted that the impedance of the input end and the output end of the power amplifier is not completely equal, but the impedance of the input end is slightly larger than that of the output end, so when designing the input end microstrip line and the output end microstrip line, as shown in FIG. 8, the width of the tail end of the input end microstrip line is slightly smaller than the width of the head section of the input end microstrip line. Figure 2

[0029] ​Further, in combination with Figure 1 , Figure 2 , when the number of filter units is four, the width of the filter microstrip lines (i.e. filter microstrip lines MSL5, MSL6) of the first two filter units is 2-3 mm; the width of the filter microstrip lines (i.e. filter microstrip lines MSL7, MSL8, MSL9) of the last two filter units is 0.8-1.2 mm. In this embodiment, the output microstrip line composed of filter microstrip lines MSL5, MSL6, MSL7, MSL8, MSL9 can be equivalent to an inductance and form an LC filter network with each filter capacitance, and can also be equivalent to an impedance and match the impedance of the power amplifier through impedance tapering. That is, while achieving out-of-band harmonic suppression, good impedance matching is also achieved. Moreover, when matching the impedance, filter microstrip line MSL5, as the impedance transformation line of the output end of the power amplifier, can match the impedance of the output end of the power amplifier. The width of the microstrip line gradually decreases in a step-like manner from filter microstrip line MSL6 to filter microstrip line MSL7, thereby achieving impedance tapering and matching the impedance of the external circuit.

[0030] Further, in combination with Figure 1 , Figure 2 , the input microstrip line includes a first microstrip line MSL1 and a second microstrip line MSL2 connected in series, the width of the first microstrip line MSL1 is 0.8-1.2 mm, and the width of the second microstrip line MSL2 is 1-2.5 mm. In this embodiment, the first microstrip line MSL1 is a 50Ω impedance line, and its length is not required; the second microstrip line MSL2 is an input impedance transformation line, and its length can be 1.0-3.0 mm.

[0031] Further, in combination with Figure 1 , Figure 2 , the microwave amplification module of this embodiment further includes a feeding unit 30, which includes a feeding microstrip line MSL3 and a decoupling capacitor C1, for example, a high-Q capacitor of 5.6 pF-15 pF, wherein the first end of the feeding microstrip line MSL3 is connected to the output end (drain) of the power amplifier 10, the second end of the feeding microstrip line MSL3 is connected to a direct current power supply Vd, the first end of the decoupling capacitor C1 is connected to the second end of the feeding microstrip line MSL3, and the second end of the decoupling capacitor C1 is grounded. The length of the feeding microstrip line MSL3 is related to 1 / 4 of the wavelength of the microwave signal fundamental wave, for example, the length is 12.0-16.0 mm, in addition, the width is 0.8-1.2 mm, and the resistance is 50Ω.

[0032] In this embodiment, the feeding microstrip line MSL3 is used as the feeding line of the power amplifier drain, and its length is related to 1 / 4 of the wavelength (λ) of the microwave signal fundamental wave, i.e., the power amplifier is fed by a λ / 4 microstrip line. For the fundamental wave signal in the microwave signal, the feeding unit appears as an open circuit from the drain of the power amplifier, and cannot be conducted, thus preventing the leakage of the microwave signal fundamental wave to the DC power supply, which not only reduces the loss of the fundamental wave signal, but also avoids the influence of the fundamental wave signal on the DC power supply. At the same time, for the second harmonic wave in the microwave signal, the feeding unit appears as a short circuit, thus preventing the second harmonic wave from flowing out of the DC path. In summary, the feeding microstrip line MSL3 can transmit the DC voltage signal of the DC power supply to the drain of the power amplifier 10, but the microwave signal cannot flow away from the feeding unit, which not only makes the operation of the DC power supply more stable, ensuring the good performance of the power supply system, but also reduces the loss of microwave power and improves the additional efficiency of the power amplifier.

[0033] Further, in combination with Figure 1 , Figure 2 , the feeding unit 30 further includes a power supply microstrip line MSL4 with an impedance of 50Ω, and the power supply microstrip line MSL4 is connected between the second end of the feeding microstrip line MSL3 and the DC power supply. The power supply microstrip line MSL4 is used to match the impedance of the external line, and has no length requirement.

[0034] Further, since the DC power supply signal output by the DC power supply can reach the output port (OUT) of the microwave amplification module along the output end microstrip line of the power amplifier 10 through the feeding unit 30, and can reach the input port (IN) of the microwave amplification module along the input end microstrip line, in order to prevent the DC power supply signal from reaching the output port and the input port, in combination with Figure 1 , Figure 2 , the microwave amplification module of this embodiment further includes an output coupling capacitor C5 and an input coupling capacitor C7 Figure 1 (not shown, refer to Figure 2 ), wherein the output coupling capacitor C5 is connected to the output end microstrip line, and the input coupling capacitor C7 is connected to the input end microstrip line. In this embodiment, the output coupling capacitor C5 and the input coupling capacitor C7 can respectively isolate the DC power supply signal to prevent the DC power supply signal from reaching the output port and the input port of the microwave amplification module.

[0035] Further, in combination with Figure 1 , Figure 2, the output coupling capacitor C5 is arranged at the rear section of the output microstrip line, and the input coupling capacitor C7 is arranged at the front section of the input microstrip line. In this embodiment, the closer to the rear section of the output microstrip line, the closer the resistance value of the microstrip line at the corresponding position to 50 ohms, and the closer the impedance matching with the DC power supply. Correspondingly, the closer to the front section of the input microstrip line, the closer the resistance value of the microstrip line at the corresponding position to 50 ohms, and the closer the impedance matching with the DC power supply. Therefore, by arranging the output coupling capacitor C5 at the rear section of the output microstrip line and the input coupling capacitor C7 at the front section of the input microstrip line, the DC power supply signal can be more effectively prevented from reaching the output port and the input port of the microwave amplification module.

[0036] Finally, regarding the microstrip lines in this embodiment, for example, MSL1, MSL2, MSL3, MSL4, MSL5, MSL6, MSL7, MSL8, and MSL9, it should be further explained that, in combination with Figure 3 When the microstrip lines are arranged on the PCB, the microstrip line 1, the dielectric layer 2, and the copper foil layer (ground layer) 3 are arranged in sequence from top to bottom, and the microstrip line 1 and the ground layer can be made of a copper foil with a thickness of 0.035 mm, and the dielectric layer can be made of RO4350B circuit board material with a thickness of 0.508 mm. In addition, the shapes of all the microstrip lines (MSL1, MSL2, MSL3, MSL4, MSL5, MSL6, MSL7, MSL8, and MSL9) in this embodiment include but are not limited to straight lines, curved lines, serpentine lines, right-angle bending cut angles, etc.

[0037] In summary, the technical solutions of the above-mentioned embodiments improve the additional efficiency of the power amplifier through the following improvements:

[0038] 1. Harmonic suppression: At different length positions of the output microstrip line, in combination with capacitors with appropriate parameters, an equivalent low-pass low-resistance fourth-order LC filter is formed, which can effectively suppress out-of-band harmonics, thereby improving the additional efficiency of the power amplifier;

[0039] 2. Impedance matching: The width of the microstrip line is gradually changed to achieve impedance matching with the input / output end of the power amplifier, thereby improving the additional efficiency of the power amplifier;

[0040] 3. Using λ / 4 microstrip line for feeding: The fundamental wave signal of the microwave signal can be prevented from leaking to the DC power supply, reducing the loss of the fundamental wave signal, thereby improving the additional efficiency of the power amplifier.

[0041] Test results show that by implementing the technical solutions of the above-mentioned embodiments, the additional efficiency of the power amplifier can be improved to 78% to 80%, which is much greater than 50%.

[0042] In addition, the technical scheme of the embodiment can improve the additional efficiency of the power amplifier and has the following beneficial effects:

[0043] 1. The length of the microstrip line in the transverse direction and the longitudinal direction is not more than λ / 2, compared with the existing microstrip circuit stub, cavity filter and other filter devices, the size and volume are smaller, and the design trend of product miniaturization is met.

[0044] 2. The microwave power amplification module can be directly designed on the PCB board, compared with the existing cavity filter and other filter devices, without the need for special substrates such as silicon, sapphire or diamond, the circuit cost is lower.

[0045] 3. The leakage of the microwave signal to the direct current power supply can be prevented, and the good performance of the power supply system is ensured.

[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. An aerosol forming apparatus comprising a microwave generating module and a microwave amplification module, the microwave amplification module comprising a power amplifier for power amplifying a microwave signal generated by the microwave generating module and a filter connected to an output of the power amplifier, characterised in that, The filter comprises a plurality of filter units for suppressing different harmonic signals respectively, wherein each filter unit comprises a filter microstrip line and a filter capacitor, the filter microstrip lines in each filter unit are connected in sequence end to end to form an output microstrip line, and the filter capacitor in each filter unit is connected between the output end of the filter microstrip line and the ground.

2. An aerosol-forming device according to claim 1, characterised in that, The number of filter units is three, four or five.

3. An aerosol-forming device according to claim 1 or 2, wherein, The microwave amplification module further comprises an input microstrip line connected to the input end of the power amplifier, and the width of the input microstrip line increases in steps, and the width of the output microstrip line decreases in steps.

4. An aerosol-forming device according to claim 3, characterised in that, The number of filter units is four, and the width of the filter microstrip line of the first two filter units is 2-3 mm, and the width of the filter microstrip line of the last two filter units is 0.8-1.2 mm.

5. An aerosol-forming device according to claim 3, wherein, The input microstrip line comprises a first microstrip line and a second microstrip line connected in sequence, the width of the first microstrip line is 0.8-1.2 mm, and the width of the second microstrip line is 1-2.5 mm.

6. An aerosol-forming device according to claim 5, wherein, The microwave amplification module further comprises a feeding unit, and the feeding unit comprises a feeding microstrip line and a decoupling capacitor, wherein the first end of the feeding microstrip line is connected to the output end of the power amplifier, the second end of the feeding microstrip line is connected to a direct current power supply, the first end of the decoupling capacitor is connected to the second end of the second microstrip line, the second end of the decoupling capacitor is grounded, and the length of the feeding microstrip line is related to 1 / 4 of the wavelength of the fundamental wave of the microwave signal.

7. An aerosol-forming device according to claim 6, characterised in that, The feeding unit further comprises a power supply microstrip line with an impedance of 50 ohms, and the power supply microstrip line is connected between the second end of the feeding microstrip line and the direct current power supply.

8. An aerosol-forming device according to claim 6, characterised in that, The microwave amplification module further comprises: an output coupling capacitor (C5) connected to the output microstrip line; and / or, an input coupling capacitor (C7) connected to the input microstrip line.

9. The aerosol-forming device according to claim 8, characterized in that the output coupling capacitor (C5) is arranged at a rear section of the output microstrip line; and / or the input coupling capacitor (C7) is arranged at a front section of the input microstrip line.

10. An aerosol-forming device according to claim 3, characterised in that, The microwave amplification module further comprises a dielectric layer and a ground layer arranged below the input microstrip line and the output microstrip line respectively.

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