CN102740580B - A kind of Small-power microwave microplasma integration source - Google Patents

Abstract

The invention discloses a low-power integrated microwave micro-plasma source, which comprises a phase-locked loop frequency synthesizer; an adjustable attenuator connected with the phase-locked loop frequency synthesizer; a broadband power amplifier connected with the adjustable attenuator; a circulator , connected with broadband power amplifier; planar microstrip gradient spiral inductively coupled coil, connected with circulator. When working, low-power microwaves are input to the planar microstrip gradient spiral inductively coupled coil to excite microwave microplasma. The invention has the advantages of adjustable frequency, adjustable power, power source protection, small size and portability.

Description

A low-power integrated microwave micro-plasma source

technical field

The invention relates to the technical field of microwave plasma sources, in particular to a low-power integrated microwave micro-plasma source.

Background technique

Low-power microwave micro-plasma technology is a high-tech developed in recent years that integrates microelectronics technology, microwave technology and plasma technology. It develops along with the development of MEMS technology. Micro plasmas include direct current micro plasmas, radio frequency micro plasmas and microwave micro plasmas. When the discharge space is further reduced to a nanometer size, it becomes a nanoplasma. Because microelectromechanical systems (MEMS) have the characteristics of low loss, high isolation, small size, low manufacturing cost, and easy integration with IC and MMIC circuits, low-power packaging and active integration of microwave plasma can be realized through MEMS technology. Therefore, combining microwave plasma with MEMS technology can greatly change the structure and characteristics of plasma.

Microwave plasma can be widely used in high-tech fields such as new materials, microelectronics and chemistry. With the development of miniaturization of microwave plasma, the circuit size is required to be at the millimeter level, micron level or even nanometer level. The previous centimeter or even meter level Large-area microwave plasmas are no longer applicable. In the research of microwave microplasma, the structural packaging and system integration of low-power microwave microplasma source are two very important links. The low-power planar spiral inductively coupled microwave micro-plasma source uses MEMS technology to excite micro-sized plasma through micro-power microwaves. For example, the gas is ionized with a microwave power of no more than 1 to 3 watts, and a 10 mm or even 0.2 mm size plasma is generated. plasma. Because this technology has good application prospects in the fields of sterilization and disinfection of biological MEMS, processing of small-sized materials, microchemical analysis systems, and micro propulsion, it has received more and more attention.

At present, the low-power microwave micro-plasma source used abroad mainly adopts the frequency band of 900MHz, and the output power is 4 watts. Although the structure is simple, it can only work at a single frequency point and single power, that is, neither frequency nor power can be adjusted. If the structure and frequency of the microstrip planar gradient spiral inductance coil change, the hardware circuit of the power source needs to be redesigned.

Contents of the invention

The invention overcomes the above-mentioned defects of the power source, and preferably realizes adjustable frequency, adjustable power, power source protection and small-scale portability of the low-power microwave micro-plasma source.

According to microwave circuit theory, the system integration using phase-locked loop frequency synthesizer, adjustable attenuator, broadband power amplifier, circulator, etc. can meet the requirements of the radiation unit to excite microwave micro-plasma. The low-power integrated microwave micro-plasma source adjusts the frequency through the host computer program, the phase-locked loop frequency synthesizer generates microwave signals, the potentiometer adjusts the attenuation, and the microwave power amplified by the broadband power amplifier is input to the microstrip plane gradient spiral inductor through the circulator On the coil, microwave micro-plasma is excited under the condition of normal pressure or low pressure.

The present invention proposes a low-power integrated microwave micro-plasma source, comprising:

A phase-locked loop frequency synthesizer, used to generate microwave frequency oscillation signals with excellent performance;

An adjustable attenuator, connected to the phase-locked loop frequency synthesizer, is used to increase the adjustable range of the power of the microwave frequency oscillation signal;

a broadband power amplifier, connected to the adjustable attenuator, for amplifying the microwave frequency oscillation signal;

A circulator, connected to the broadband power amplifier, is used to reduce the impact of the impedance mismatch caused by the excitation of microwave micro-plasma on the small microwave power source;

A planar microstrip tapered spiral inductively coupled coil is connected with the circulator and used to excite microwave microplasma.

Wherein, the frequency output range of the phase-locked loop frequency synthesizer is 2.3GHz to 2.6GHz.

Wherein, the attenuation range of the adjustable attenuator is -2dB to -17dB.

Wherein, the power output range of the broadband power amplifier is +20dBm to +40dBm, and the peak power is greater than 43dBm.

Wherein, the frequency range of the circulator is 2.3GHz to 2.5GHz, the insertion loss is 0.25dB to 0.3dB, and the isolation is 20dB to 25dB.

Wherein, the number of turns of the planar microstrip gradient spiral inductively coupled coil is 3; the coil width of the planar microstrip gradient spiral inductively coupled coil is 100 μm to 400 μm, and the coil spacing is 100 μm to 400 μm, and the coil width and the coil spacing It gradually decreases from the outer ring to the inner ring.

Wherein, a matching load is further included; the matching load is connected to the circulator.

Wherein, the frequency range of the matching load is from DC to 2.7GHz, the return loss is greater than 20dB, and the power capacity is 150W.

Wherein, a matching circuit is further included, and the matching circuit is connected to the circulator and the planar microstrip tapered spiral inductively coupled coil.

Wherein, the phase-locked loop frequency synthesizer, adjustable attenuator, broadband power amplifier and circulator are arranged in the shielding box.

The low-power integrated microwave micro-plasma source provided by the invention is a device for exciting microwave micro-plasma, and has the advantages of adjustable frequency, adjustable power, power source protection, small size and portability. The integration of the small microwave power source and the planar microstrip gradient spiral inductive coupling coil makes the whole device miniaturized; adjusting the host computer program makes the output frequency of the phase-locked loop frequency synthesizer adjustable; changing the size of the adjustable attenuator makes the output microwave power adjustable The circulator can reduce the impact of the impedance mismatch caused by the excitation of microwave micro-plasma on the small microwave power source, and play a role in protecting the small microwave power source.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the low-power integrated microwave micro-plasma source of the present invention.

Fig. 2 is a schematic circuit diagram of a low-power integrated microwave micro-plasma source in this embodiment.

Detailed ways

The specific implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the protection scope of the present invention should not be limited thereby.

As shown in Figure 1-2, 1-phase-locked loop frequency synthesizer, 2-adjustable attenuator, 3-broadband power amplifier, 4-circulator, 5-matching load, 6-plane microstrip gradient spiral inductive coupling coil , 7-matching circuit, 8-interface circuit, 9-USB interface, 10-host computer, 21-PIN tube, 22-3dB bridge, 31-drive amplifier, 32-final broadband power amplifier.

As shown in Figure 1, the low-power integrated microwave micro-plasma source of the present invention includes:

A phase-locked loop frequency synthesizer 1, which is used to generate a microwave frequency oscillation signal with excellent performance;

The adjustable attenuator 2 is connected with the phase-locked loop frequency synthesizer 1, and is used to increase the adjustable range of the power of the microwave frequency oscillation signal;

The broadband power amplifier 3 is connected with the adjustable attenuator 2, and is used for amplifying the input microwave frequency oscillation signal to make it reach a sufficient power level in a wider frequency band;

The circulator 4 is connected with the broadband power amplifier 3, and is used to reduce the impact of the impedance mismatch brought by the excitation of the microwave micro-plasma on the small microwave power source, and protect the small microwave power source;

The planar microstrip tapered spiral inductively coupled coil 6 is connected with the circulator 4 and is used to excite microwave microplasma.

Wherein, the frequency output range of the phase-locked loop frequency synthesizer 1 is 2.3GHz to 2.6GHz.

Wherein, the attenuation range of the adjustable attenuator 2 is from -2dB to -17dB.

Wherein, the power output range of the broadband power amplifier 3 is +20dBm to +40dBm, and the peak power is greater than 43dBm.

Wherein, the frequency range of the circulator 4 is 2.3GHz to 2.5GHz, the insertion loss is 0.25dB to 0.3dB, and the isolation is 20dB to 25dB.

Among them, the number of turns of the planar microstrip gradient spiral inductively coupled coil 6 is 3; the coil width of the planar microstrip gradient spiral inductively coupled coil 6 is 100 μm to 400 μm, and the coil spacing is 100 μm to 400 μm, and the coil width and coil spacing are determined by the outer ring gradually decreases toward the inner circle.

Wherein, a matching load 5 is further included; the matching load 5 is connected to the circulator 4 .

Wherein, the frequency range of the matching load 5 is from direct current to 2.7 GHz, the return loss is greater than 20 dB, and the power capacity is 150 watts.

Wherein, a matching circuit 7 is further included, and the matching circuit 7 is connected to the circulator 4 and the planar microstrip tapered spiral inductively coupled coil 6 .

Wherein, the phase-locked loop frequency synthesizer 1, the adjustable attenuator 2, the broadband power amplifier 3 and the circulator 4 are arranged in the shielding box.

Example 1

In this embodiment, the chip of PLL frequency synthesizer 1 is ADF4350, the output frequency of PLL frequency synthesizer 1 is 2.45GHz, and the overall phase noise is -73dBc at frequency deviation 1kHz, and is -87dBc/Hz at frequency deviation 100kHz . The phase-locked loop frequency synthesizer 1 is connected to a host computer 10 through an interface circuit 8 and a USB interface 9 . The host computer 10 sends data to the interface circuit 8 through the USB interface 9, and the interface circuit 8 completes the conversion from the USB interface 9 to the three-wire serial port by the microcontroller chip CY7C68013, and realizes the data transmission between the host computer 10 and the phase-locked loop frequency synthesizer 1.

In this embodiment, the adjustable attenuator 2 includes a PIN tube 21 and a 3dB bridge 22 . The chip of the PIN tube 21 of the adjustable attenuator 2 is HSMP3814, the chip of the 3dB bridge 22 is JP503S, and the attenuation value of the adjustable attenuator 2 is -10dB.

In this embodiment, the broadband power amplifier 3 includes a driving amplifier 31 and a final broadband power amplifier 32 . The chip of the driving amplifier 31 is SBB-4089Z, the chip of the final broadband power amplifier 32 is MW7IC2725, and the power output of the final broadband power amplifier 32 is +32dBm.

In this embodiment, the chip of the circulator 4 is MAFR-000488, and the chip of the 50Ω matching load 5 is E150N50X4.

In this embodiment, the number of turns of the planar microstrip gradient spiral inductively coupled coil 6 is 3, the coil width and coil spacing gradually decrease from outside to inside, and the innermost coil terminal is open. The input end of the planar microstrip tapered spiral inductively coupled coil 6 uses an SMA connector.

In this embodiment, the coil part of the planar microstrip tapered spiral inductively coupled coil 6 is made of high-conductivity metal material, and the high-conductivity metal material is gold.

In this embodiment, the substrate part of the planar microstrip tapered spiral inductive coupling coil 6 adopts a high-temperature-resistant, corrosion-resistant low-loss dielectric substrate, and the low-loss dielectric substrate is alumina ceramics.

As shown in Figure 2, a low-power integrated microwave micro-plasma source is provided in this embodiment, including a frequency source synthesizer 1, an adjustable attenuator 2, a broadband power amplifier 3, a circulator 4, a matching circuit 7 and a plane The microstrip tapered spiral inductively coupled coil 6, the above-mentioned components are connected in sequence. A phase-locked loop frequency synthesizer 1, an adjustable attenuator 2, a broadband power amplifier 3 and a circulator 4 are arranged in the shielding box. The 50Ω matching load 5 is connected to the circulator 4 .

When working, the phase-locked loop frequency synthesizer 1 is connected to the host computer 10 through the interface circuit 8 and the USB interface 9 in sequence. The host computer 10 controls the phase-locked loop frequency synthesizer 1 to generate a microwave frequency oscillating signal of 2.45GHz, and adjusts the amplitude of the microwave frequency oscillating signal through the adjustable attenuator 2, so that the attenuation of the adjustable attenuator 2 is -8dB, and the microwave frequency The oscillating signal is sequentially input to the drive amplifier 31 of the broadband power amplifier 3 and the final broadband power amplifier 32 for power amplification, and the power of the microwave frequency oscillating signal after amplification is +32dBm. The microwave frequency oscillating signal is amplified by the microwave power and fed into the planar microstrip gradient spiral inductively coupled coil 6 through the circulator 4, and the microwave micro-plasma is excited under the pressure condition of 0.04Torr to 10Torr, so as to realize the low-power microwave micro-plasma source .

The matching circuit 7 adopts a self-resonant structure matching circuit or an interdigitated capacitor structure matching circuit, which is used to adjust the planar microstrip gradient spiral inductive coupling coil 6, so that the input impedance seen from the left end of the matching circuit 7 is 50Ω.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the implementation scope of the present invention. Anyone with ordinary knowledge in the technical field may make various changes and modifications without departing from the spirit and scope of the present invention, and the protection scope of the present invention shall be determined by the protection scope defined in the claims.

Claims (6)

1. A low-power integrated microwave micro-plasma source, characterized in that it comprises: A phase-locked loop frequency synthesizer (1), used to generate a microwave frequency oscillating signal with excellent performance, the frequency output range of the phase-locked loop frequency synthesizer (1) is 2.3GHz to 2.6GHz; the phase-locked loop frequency synthesizer The chip of device (1) is ADF4350, and described phase-locked loop frequency synthesizer (1) carries out data transmission with upper computer; An adjustable attenuator (2), connected to the phase-locked loop frequency synthesizer (1), is used to increase the adjustable range of the power of the microwave frequency oscillation signal; the adjustable attenuator (2) includes a PIN tube (21) and 3dB electric bridge (22); a broadband power amplifier (3), connected to the adjustable attenuator (2), for amplifying the microwave frequency oscillation signal; A circulator (4), connected to the broadband power amplifier (3), is used to reduce the impact of the impedance mismatch caused by the excitation of microwave micro-plasma on the small microwave power source; A planar microstrip gradient spiral inductively coupled coil (6), connected to the circulator (4), used to excite microwave microplasma; The number of turns of the planar microstrip gradient spiral inductively coupled coil (6) is 3; the coil width of the planar microstrip gradient spiral inductively coupled coil (6) is 100 μm to 400 μm, and the coil pitch is 100 μm to 400 μm, and the coil The width and coil spacing gradually decrease from the outer ring to the inner ring; Matching circuit (7), described matching circuit (7) connects described circulator (4) and planar microstrip gradient spiral inductive coupling coil (6); The phase-locked loop frequency synthesizer (1), adjustable attenuator (2), broadband power amplifier (3) and circulator (4) are arranged in a shielding box. 2. The low-power integrated microwave micro-plasma source according to claim 1, wherein the attenuation range of the adjustable attenuator (2) is from -2dB to -17dB. 3. low-power integrated microwave micro-plasma source as claimed in claim 1, is characterized in that, the power output range of described broadband power amplifier (3) is +20dBm to +40dBm, and peak power is greater than 43dBm. 4. low-power integrated microwave micro-plasma source as claimed in claim 1, is characterized in that, the frequency range of described circulator (4) is 2.3GHz to 2.5GHz, and insertion loss is 0.25dB to 0.3dB, and isolation degree is 20dB to 25dB. 5. The low-power integrated microwave micro-plasma source according to claim 1, further comprising a matching load (5); the matching load (5) is connected to the circulator (4). 6. low-power integrated microwave micro-plasma source as claimed in claim 5, is characterized in that, the frequency range of described matching load (5) is direct current to 2.7GHz, return loss is greater than 20dB, and power capacity is 150 watts.