High-resolution radio frequency signal generation circuit, system and method

Abstract

The invention belongs to the field of radio frequency signal generators, and particularly relates to a high-resolution radio frequency signal generation circuit, system and method. The circuit comprises a digital frequency synthesizer DDS-1, a digital frequency synthesizer DDS-2, a radio frequency selection switch MUX-1, a radio frequency selection switch MUX-2 and a radio frequency power amplifier, and the input end of the digital frequency synthesizer DDS-1 is connected with an external controller. According to the invention, through a circuit form of connecting two digital frequency synthesizers DDS in series, a radio frequency signal with adjustable frequency and adjustable amplitude can be provided to the outside; an external radio-frequency signal can be received and synchronized with the external radio-frequency signal, and the output amplitude can be adjusted by 360 degrees based on the frequency signal; a radio frequency signal for synchronization can be provided to the outside; according to the invention, a controller can input a pulse signal carrier to a radio frequency output signal, so that the radio frequency output signal is a continuous signal or a pulse signal, a scheme which can only be realized by a multiplier and an FPGA (Field Programmable Gate Array) is solved, and the hardware cost and the development difficulty are reduced.

Description

Technical Field

[0001] The present invention relates to a radio frequency signal generating circuit, system and method, and in particular to a high-resolution radio frequency signal generating circuit, and a high-resolution radio frequency signal generating system and a high-resolution radio frequency signal generating method based on the circuit. Background Art

[0002] RF generator is a plasma supporting power source, which is composed of signal generator, impedance matcher and impedance power meter. RF generator technology is a new high-tech field in my country in the late 1980s. RF generators are widely used, mainly in the following specific fields: semiconductor production, plasma etching, vacuum coating, PECVD, plasma cleaning, physical vapor deposition (PVD), chemical vapor deposition (CVD), RF sputtering, etc.

[0003] Modern RF generators have made great progress, from the electron tube power supply in the 1980s to the current transistor RF generator, with power ranging from watts, hundreds of watts, kilowatts to megawatts, and frequencies including 2Mhz / 13.56Mhz / 27.12Mhz / 40.68Mhz, etc., and applications have also expanded from the previous vacuum field to other fields, such as semiconductors and beauty.

[0004] The RF signal generating circuit in the RF generator is the core circuit of the RF generator and has a great influence on the technical indicators of the RF generator. In the prior art, the RF signal generating circuit usually adopts a multiplier + FPGA structure, which has the disadvantages of high hardware cost and great development difficulty. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of high hardware cost and great development difficulty in the existing radio frequency signal generating circuit using a multiplier + FPGA structure, and to provide a high-resolution radio frequency signal generating circuit, system and method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A high-resolution radio frequency signal generating circuit, which is special in that:

[0008] It includes a digital frequency synthesizer DDS-1, a digital frequency synthesizer DDS-2, a radio frequency selection switch MUX-1, a radio frequency selection switch MUX-2 and a radio frequency power amplifier;

[0009] The input end of the digital frequency synthesizer DDS-1 is connected to an external controller, and is used to receive a first SPI communication signal sent by the external controller, and adjust the frequency of its output radio frequency signal according to the first SPI communication signal; the output end of the digital frequency synthesizer DDS-1 is connected to a first input end of a radio frequency selection switch MUX-1, and is used to output the adjusted radio frequency signal to the radio frequency selection switch MUX-1;

[0010] The second input end and the third input end of the RF selection switch MUX-1 respectively receive the RF signal input by the external CEXIN interface and the IO communication signal sent by the external controller, and are used to select the RF signal input by the external CEX IN interface or the RF signal output by the digital frequency synthesizer DDS-1 for output according to the IO communication signal; the output end of the RF selection switch MUX-1 is respectively connected to the external controller, the external CEXOUT interface and the system clock CLK IN port of the digital frequency synthesizer DDS-2, and is used to output the selected RF signal to the external controller, the external CEX OUT interface and the digital frequency synthesizer DDS-2 respectively;

[0011] The second input terminal and the third input terminal of the digital frequency synthesizer DDS-2 respectively receive the second SPI communication signal and the REF signal sent by the external controller, and adjust the frequency of its output radio frequency signal to be consistent with the frequency of its input radio frequency signal according to the second SPI communication signal, and adjust the amplitude of its output radio frequency signal according to the REF signal; the output terminal of the digital frequency synthesizer DDS-2 is connected to the first input terminal of the radio frequency selection switch MUX-2, and is used to output the adjusted radio frequency signal to the radio frequency selection switch MUX-2;

[0012] The second input end of the RF selection switch MUX-2 is connected to the external controller, and is used to receive the IO or Square signal sent by the external controller, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform;

[0013] The input end of the RF power amplifier is connected to the output end of the RF selection switch MUX-2, and is used to amplify the power of the received RF signal and then output it.

[0014] Further, it also includes a PA unit;

[0015] The input end of the PA unit is connected to the output end of the radio frequency selection switch MUX-1, and the output end is connected to the external CEX OUT interface.

[0016] Furthermore, it also includes a shaping conversion unit;

[0017] The input end of the shaping conversion unit is connected to the output end of the RF selection switch MUX-1, and the output end is connected to the input end of the external controller. It is used to shape and convert the RF signal output by the RF selection switch MUX-1 into a TTL signal, and then output it to the controller for frequency measurement.

[0018] Furthermore, the models of the digital frequency synthesizer DDS-1 and the digital frequency synthesizer DDS-2 are both AD9954;

[0019] The models of the radio frequency selection switch MUX-1 and the radio frequency selection switch MUX-2 are both TS5A22362;

[0020] The model of the radio frequency power amplifier is THS3491.

[0021] Furthermore, the DAC_RSET pin of the digital frequency synthesizer DDS-2 is connected to an external controller, and is used to control the amplitude of the output radio frequency signal according to the current size of the REF signal sent by the external controller.

[0022] At the same time, the present invention also provides a high-resolution radio frequency signal generation system, which is special in that:

[0023] It includes a controller and the aforementioned high-resolution radio frequency signal generating circuit;

[0024] The first output terminal of the controller is connected to the input terminal of the digital frequency synthesizer DDS-1, and is used to send a first SPI communication signal according to user settings to control the digital frequency synthesizer DDS-1 to achieve frequency adjustment of the radio frequency signal;

[0025] The second output terminal of the controller is connected to the third input terminal of the RF selection switch MUX-1, and is used to send an IO communication signal according to the user setting to control the RF selection switch MUX-1 to select a corresponding RF signal for output;

[0026] The fourth output terminal and the fifth output terminal of the controller are respectively connected to the second input terminal and the third input terminal of the digital frequency synthesizer DDS-2, and are used to send the second SPI communication signal and the REF signal according to the user setting to control the digital frequency synthesizer DDS-2 to adjust the frequency and amplitude of the radio frequency signal;

[0027] The sixth output terminal of the controller is connected to the second input terminal of the RF selection switch MUX-2, and is used to output an IO or Square signal according to the user setting to control the RF selection switch MUX-2 to cut off or restore the RF signal output and adjust the waveform of the RF signal;

[0028] The detection end of the controller is connected to the output end of the RF selection switch MUX-1, and sends the RF signal output by the RF selection switch MUX-1 to an external counter for frequency measurement to ensure that the frequency of the RF signal is within the frequency range set by the user.

[0029] At the same time, the present invention also provides a high-resolution radio frequency signal generation method, which is based on the above-mentioned high-resolution radio frequency signal generation circuit, and its special feature is that it includes the following steps:

[0030] Step 1, receiving a first SPI communication signal sent by an external controller through a digital frequency synthesizer DDS-1, adjusting the frequency of its output radio frequency signal according to the first SPI communication signal, and outputting it to a radio frequency selection switch MUX-1;

[0031] Step 2, receiving the RF signal input from the external CEX IN interface and the IO communication signal sent by the external controller through the RF selection switch MUX-1, and selecting to output the RF signal input from the external CEX IN interface or the RF signal output from the digital frequency synthesizer DDS-1 to the external controller, the external CEX OUT interface and the digital frequency synthesizer DDS-2 according to the IO communication signal;

[0032] Step 3, receiving the second SPI communication signal and REF signal sent by the external controller through the digital frequency synthesizer DDS-2, and adjusting the frequency of its output RF signal to be consistent with the frequency of its input RF signal according to the second SPI communication signal, and adjusting the amplitude of its output RF signal according to the REF signal, and finally outputting the adjusted RF signal to the RF selection switch MUX-2;

[0033] Step 4: Receive the IO or Square signal sent by the controller through the RF selection switch MUX-2, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform;

[0034] Step 5: The received RF signal is amplified by the RF power amplifier and then outputted, thereby completing the RF signal generation.

[0035] The beneficial effects of the present invention are:

[0036] The present invention achieves the following through a circuit form in which two digital frequency synthesizers DDS are connected in series: 1. a frequency-adjustable and amplitude-adjustable radio frequency signal can be provided externally; 2. an external radio frequency signal can be received and synchronized therewith, and the output amplitude can be adjusted 360 degrees based on the frequency signal; 3. a radio frequency signal for synchronization can be provided externally; and 4. a controller input pulse signal carrier can be converted to a radio frequency output signal, so that the radio frequency output signal is a continuous signal or a pulse signal, thus solving the problem of requiring a multiplier + FPGA to be implemented, and reducing hardware costs and development difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a circuit structure schematic diagram of a high-resolution radio frequency signal generating system. DETAILED DESCRIPTION

[0038] In order to make the purpose, advantages and features of the present invention more clear, the following is a further detailed description of a high-resolution radio frequency signal generating circuit, system and method proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following specific implementation methods, the advantages and features of the present invention will be more clear.

[0039] See also Figure 1 In this embodiment, a high-resolution radio frequency signal generating system includes a controller and a high-resolution radio frequency signal generating circuit. The high-resolution radio frequency signal generating circuit mainly includes a digital frequency synthesizer DDS-1, a digital frequency synthesizer DDS-2, a radio frequency selection switch MUX-1, a radio frequency selection switch MUX-2 and a radio frequency power amplifier.

[0040] The main function of the digital frequency synthesizer DDS-1 is to provide a radio frequency signal with a fixed amplitude and adjustable frequency. The model of the digital frequency synthesizer DDS-1 is AD9954.

[0041] The main function of the digital frequency synthesizer DDS-2 is to provide a radio frequency signal with an output frequency that is the same as the input frequency and an adjustable amplitude. The model of the digital frequency synthesizer DDS-2 is AD9954.

[0042] The main functions of the RF selection switch MUX-1 and the RF selection switch MUX-2 are: selecting whether the RF signal is internal input or external input, and controlling whether the RF signal is output or not output. The model of the RF selection switch MUX-1 and the RF selection switch MUX-2 is TS5A22362.

[0043] The main function of the RF power amplifier is to amplify the power of the RF signal. The model of the RF power amplifier is THS3491.

[0044] Specifically, the input end of the digital frequency synthesizer DDS-1 is connected to an external controller, for receiving a first SPI communication signal sent by the external controller, and adjusting the frequency of its output RF signal according to the first SPI communication signal; the output end of the digital frequency synthesizer DDS-1 is connected to the first input end of the RF selection switch MUX-1, for outputting the adjusted RF signal to the RF selection switch MUX-1.

[0045] The second input end and the third input end of the RF selection switch MUX-1 respectively receive the RF signal input by the external CEX IN interface and the IO communication signal sent by the external controller, and are used to select the RF signal input by the external CEX IN interface or the RF signal output by the digital frequency synthesizer DDS-1 for output according to the IO communication signal; the output end of the RF selection switch MUX-1 is connected to the system clock CLK IN port of the digital frequency synthesizer DDS-2, and outputs the selected RF signal to the digital frequency synthesizer DDS-2; at the same time, the output end of the RF selection switch MUX-1 is connected to the external CEX OUT interface through the PA unit, and outputs the selected RF signal to the external CEX OUT interface, and the PA unit avoids the clock abnormality of the external CEX OUT interface due to short circuit or external interference; at the same time, the output end of the RF selection switch MUX-1 is also connected to the controller through the shaping conversion unit, and is used to shape and convert the RF signal output by the RF selection switch MUX-1 into a 13.56MHz TTL signal, and then output it to the controller, and the frequency is measured by the counter in the controller to ensure that the frequency range of the external input is appropriate.

[0046] The second input end of the digital frequency synthesizer DDS-2 receives the second SPI communication signal sent by the external controller, and adjusts the frequency of its output RF signal to be consistent with the frequency of its input RF signal according to the second SPI communication signal. The DAC_RSET pin of the digital frequency synthesizer DDS-2 is connected to the controller, and at the same time adjusts the amplitude of its output RF signal according to the current size of the REF signal sent by the external controller; the output end of the digital frequency synthesizer DDS-2 is connected to the first input end of the RF selection switch MUX-2, and is used to output the adjusted RF signal to the RF selection switch MUX-2.

[0047] The second input end of the RF selection switch MUX-2 is connected to the controller, and is used to receive the IO or Square signal sent by the controller, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform; the input end of the RF power amplifier is connected to the output end of the RF selection switch MUX-2, and is used to amplify the power of the received RF signal and output it.

[0048] A high-resolution radio frequency signal generation method according to this embodiment includes the following steps:

[0049] Step 1, receiving a first SPI communication signal sent by an external controller through a digital frequency synthesizer DDS-1, adjusting the frequency of its output radio frequency signal according to the first SPI communication signal, and outputting it to a radio frequency selection switch MUX-1;

[0050] Step 2, receiving the RF signal input from the external CEX IN interface and the IO communication signal sent by the external controller through the RF selection switch MUX-1, and selecting to output the RF signal input from the external CEX IN interface or the RF signal output from the digital frequency synthesizer DDS-1 to the external controller, the external CEX OUT interface and the digital frequency synthesizer DDS-2 according to the IO communication signal;

[0051] Step 3, receiving the second SPI communication signal and REF signal sent by the external controller through the digital frequency synthesizer DDS-2, and adjusting the frequency of its output RF signal to be consistent with the frequency of its input RF signal according to the second SPI communication signal, and adjusting the amplitude of its output RF signal according to the REF signal, and finally outputting the adjusted RF signal to the RF selection switch MUX-2;

[0052] Step 4: Receive the IO or Square signal sent by the controller through the RF selection switch MUX-2, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform;

[0053] Step 5: The received RF signal is amplified by the RF power amplifier and then outputted, thereby completing the RF signal generation.

[0054] Based on the above-mentioned high-resolution radio frequency signal generating circuit, combined with an external controller, a high-resolution radio frequency signal generating system can also be formed. The system includes a controller and a high-resolution radio frequency signal generating circuit.

[0055] The first output end of the controller is connected to the input end of the digital frequency synthesizer DDS-1, and is used to send a first SPI communication signal according to user settings to control the digital frequency synthesizer DDS-1 to achieve frequency adjustment of the radio frequency signal; the second output end of the controller is connected to the third input end of the radio frequency selection switch MUX-1, and is used to send an IO communication signal according to user settings to control the radio frequency selection switch MUX-1 to select a corresponding radio frequency signal for output; the fourth output end and the fifth output end of the controller are respectively connected to the second input end and the third input end of the digital frequency synthesizer DDS-2, and are used to send a second SPI communication signal and a REF signal according to user settings to control the digital frequency synthesizer DDS-2 to achieve frequency and amplitude adjustment of the radio frequency signal; the sixth output end of the controller is connected to the second input end of the radio frequency selection switch MUX-2, and is used to output an IO or Square signal according to user settings to control the radio frequency selection switch MUX-2 to cut off or resume the output of the radio frequency signal and adjust the waveform of the radio frequency signal; the detection end of the controller is connected to the output end of the radio frequency selection switch MUX-1, and sends the radio frequency signal output by the radio frequency selection switch MUX-1 to an external counter for frequency measurement to ensure that the frequency of the radio frequency signal is within the frequency range set by the user.

Claims

1. A high-resolution radio frequency signal generating circuit, characterized in that: It includes a digital frequency synthesizer DDS-1, a digital frequency synthesizer DDS-2, a radio frequency selection switch MUX-1, a radio frequency selection switch MUX-2 and a radio frequency power amplifier; The input end of the digital frequency synthesizer DDS-1 is connected to an external controller, and is used to receive a first SPI communication signal sent by the external controller, and adjust the frequency of its output radio frequency signal according to the first SPI communication signal; The output end of the digital frequency synthesizer DDS-1 is connected to the first input end of the radio frequency selection switch MUX-1, and is used to output the adjusted radio frequency signal to the radio frequency selection switch MUX-1; The second input end and the third input end of the RF selection switch MUX-1 respectively receive the RF signal input by the external CEX IN interface and the IO communication signal sent by the external controller, and are used to select the RF signal input by the external CEX IN interface or the RF signal output by the digital frequency synthesizer DDS-1 for output according to the IO communication signal; the output end of the RF selection switch MUX-1 is respectively connected to the external controller, the external CEX OUT interface and the system clock CLK IN port of the digital frequency synthesizer DDS-2, and is used to output the selected RF signal to the external controller, the external CEX OUT interface and the digital frequency synthesizer DDS-2 respectively; The second input terminal and the third input terminal of the digital frequency synthesizer DDS-2 receive the second SPI communication signal and the REF signal sent by the external controller respectively, and adjust the frequency of its output radio frequency signal to be consistent with the frequency of its input radio frequency signal according to the second SPI communication signal, and adjust the amplitude of its output radio frequency signal according to the REF signal; The output end of the digital frequency synthesizer DDS-2 is connected to the first input end of the radio frequency selection switch MUX-2, and is used to output the adjusted radio frequency signal to the radio frequency selection switch MUX-2; The second input end of the RF selection switch MUX-2 is connected to the external controller, and is used to receive the IO or Square signal sent by the external controller, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform; The input end of the RF power amplifier is connected to the output end of the RF selection switch MUX-2, and is used to amplify the power of the received RF signal and then output it.

2. The high-resolution radio frequency signal generating circuit according to claim 1, characterized in that: It also includes a PA unit; The input end of the PA unit is connected to the output end of the radio frequency selection switch MUX-1, and the output end is connected to the external CEX OUT interface.

3. A high-resolution radio frequency signal generating circuit according to claim 1 or 2, characterized in that: Also included is a shaping conversion unit; The input end of the shaping conversion unit is connected to the output end of the RF selection switch MUX-1, and the output end is connected to the input end of the external controller. It is used to shape and convert the RF signal output by the RF selection switch MUX-1 into a TTL signal, and then output it to the external controller for frequency measurement.

4. The high-resolution radio frequency signal generating circuit according to claim 3, characterized in that: The models of the digital frequency synthesizer DDS-1 and the digital frequency synthesizer DDS-2 are both AD9954; The models of the radio frequency selection switch MUX-1 and the radio frequency selection switch MUX-2 are both TS5A22362; The model of the radio frequency power amplifier is THS3491.

5. The high-resolution radio frequency signal generating circuit according to claim 4, characterized in that: The DAC_RSET pin of the digital frequency synthesizer DDS-2 is connected to an external controller and is used to control the amplitude of the output radio frequency signal according to the current size of the REF signal sent by the external controller.

6. A high-resolution radio frequency signal generation system, characterized in that: It comprises a controller and a high-resolution radio frequency signal generating circuit as described in any one of claims 1 to 5; The first output terminal of the controller is connected to the input terminal of the digital frequency synthesizer DDS-1, and is used to send a first SPI communication signal according to user settings to control the digital frequency synthesizer DDS-1 to achieve frequency adjustment of the radio frequency signal; The second output terminal of the controller is connected to the third input terminal of the RF selection switch MUX-1, and is used to send an IO communication signal according to the user setting to control the RF selection switch MUX-1 to select a corresponding RF signal for output; The fourth output terminal and the fifth output terminal of the controller are respectively connected to the second input terminal and the third input terminal of the digital frequency synthesizer DDS-2, and are used to send the second SPI communication signal and the REF signal according to the user setting to control the digital frequency synthesizer DDS-2 to adjust the frequency and amplitude of the radio frequency signal; The sixth output terminal of the controller is connected to the second input terminal of the RF selection switch MUX-2, and is used to output an IO or Square signal according to the user setting to control the RF selection switch MUX-2 to cut off or restore the RF signal output and adjust the waveform of the RF signal; The detection end of the controller is connected to the output end of the RF selection switch MUX-1, and sends the RF signal output by the RF selection switch MUX-1 to an external counter for frequency measurement to ensure that the frequency of the RF signal is within the frequency range set by the user.

7. A high-resolution radio frequency signal generating method, based on a high-resolution radio frequency signal generating circuit according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, receiving a first SPI communication signal sent by an external controller through a digital frequency synthesizer DDS-1, adjusting the frequency of its output radio frequency signal according to the first SPI communication signal, and outputting it to a radio frequency selection switch MUX-1; Step 2, receiving the RF signal input from the external CEX IN interface and the IO communication signal sent by the external controller through the RF selection switch MUX-1, and selecting to output the RF signal input from the external CEX IN interface or the RF signal output from the digital frequency synthesizer DDS-1 to the external controller, the external CEX OUT interface and the digital frequency synthesizer DDS-2 according to the IO communication signal; Step 3, receiving the second SPI communication signal and REF signal sent by the external controller through the digital frequency synthesizer DDS-2, and adjusting the frequency of its output RF signal to be consistent with the frequency of its input RF signal according to the second SPI communication signal, and adjusting the amplitude of its output RF signal according to the REF signal, and finally outputting the adjusted RF signal to the RF selection switch MUX-2; Step 4: Receive the IO or Square signal sent by the controller through the RF selection switch MUX-2, and select to cut off or restore the output of the RF signal according to the IO or Square signal, and select whether to adjust the waveform of the output RF signal to a pulse waveform; Step 5: The received RF signal is amplified by the RF power amplifier and then outputted, thereby completing the RF signal generation.

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