A method for testing matching range of radio frequency automatic impedance matcher

Abstract

The present invention belongs to the field of impedance testing of automatic impedance matchers, and discloses a method for testing the matching range of a radio frequency automatic impedance matcher, including: reversely connecting the automatic impedance matcher so that its input end is connected to a load and its output end is connected to an impedance detector; connecting an external radio frequency signal source on one side of the impedance detector as a test signal input end; respectively detecting the values ​​of the current first vacuum capacitor and the second vacuum capacitor, and obtaining the current impedance value; then changing the matching connection direction, detecting the load impedance at the output end of the automatic impedance matcher; changing the value of any vacuum capacitor, scanning the value within its boundary value interval, and obtaining a matching range diagram. The present invention is suitable for range measurement of automatic impedance matchers of different powers, different frequencies, and different structural designs. When measuring an actual automatic impedance matcher, there is no need to pay attention to its internal structure, which is closer to the actual use scenario, the measurement process is more efficient, and the measurement results are more accurate.

Description

Technical Field

[0001] The present invention relates to the field of impedance testing of automatic impedance matchers, and in particular to a matching range testing method of a radio frequency automatic impedance matcher. Background Art

[0002] With the increasing development of current semiconductor technology, automatic impedance matching devices play a vital role in various electronic and communication systems. By automatically tuning to ensure impedance matching, it can maximize power transmission, minimize reflection loss, and improve signal quality and system efficiency. This makes automatic impedance matching devices an indispensable component in various high-performance electronic devices and systems.

[0003] Taking plasma cleaning and plasma coating as examples, the processes produced by each manufacturer, the design of the vacuum chamber and load of the coating machine or cleaning machine are very different, resulting in large differences in load impedance. When the load impedance is not within the matching range of the automatic impedance matcher, not only can the power transmission not be optimized, but it may also cause a surge in reflections. Therefore, it is necessary to accurately measure the load impedance and the matching range of the automatic impedance matcher in advance. The measurement of load impedance is often easier, but the automatic impedance matcher is often difficult to measure because it needs to tune two vacuum capacitors, has countless combinations, and is located between the RF source and the load.

[0004] The commonly used method at present is to use professional software to simulate and emulate the structural model of the automatic impedance matcher to obtain the range under ideal conditions.

[0005] The existing technology of determining the range through model derivation, impedance analysis or simulation software is affected by the power size, chassis cavity structure design, components inside the chassis, etc., and it is often impossible to obtain the actual and comprehensive parameters of key components such as vacuum capacitors and inductors. In addition, parasitic capacitance and inductance will be generated in the actual circuit, resulting in deviations between the simulation results and the actual values. At the same time, when the internal structure connection of the automatic impedance matcher is complex, the complexity of the reasoning method increases geometrically, which is not suitable for the range measurement of automatic impedance matchers with more complex structures. Summary of the invention

[0006] In view of this, the present invention provides a method for testing the matching range of a radio frequency automatic impedance matcher to solve the above-mentioned problem.

[0007] In order to solve the above technical problems, the present invention provides a method for testing the matching range of a radio frequency automatic impedance matcher, which is characterized by comprising:

[0008] Reverse the connection of the automatic impedance matcher so that its input end is connected to the load and its output end is connected to the impedance detector; connect an external RF signal source to one side of the impedance detector as the test signal input end;

[0009] Respectively detecting the values ​​of the first vacuum capacitor and the second vacuum capacitor of the current automatic impedance matcher, and obtaining the impedance value of the current automatic impedance matcher;

[0010] Locking the values ​​of the first vacuum capacitor and the second vacuum capacitor, changing the matching connection direction, and detecting the load impedance at the output end of the automatic impedance matcher;

[0011] By changing the value of any vacuum capacitor and scanning the value within its boundary value interval, a matching range diagram of the automatic impedance matcher is obtained.

[0012] As an option, the maximum value of any vacuum capacitance is normalized to 1 before measurement.

[0013] As an optional method, the connection direction of the matching is changed, and the load impedance at the output end of the automatic impedance matching device is detected, including:

[0014] When the automatic impedance matcher is reversely connected, a load is connected to the input end of the automatic impedance matcher, and the reverse impedance is measured at the load end of the automatic impedance matcher; the reverse impedance ZL=r+xj;

[0015] While keeping the capacitor position of the automatic impedance matcher unchanged, adjust the automatic impedance matcher to be in forward connection, and determine whether the overall impedance value composed of the automatic impedance matcher and the input end signal source is equal to the reverse impedance measured above;

[0016] If they are equal, connect a load with impedance ZX=r-xj at its load end to make impedance ZX and ZL form a conjugate match; where ZL and ZX are impedances, r is resistance, x is reactance, and j is an imaginary unit.

[0017] As an optional method, the value of any vacuum capacitor is changed, and the value within the boundary value interval is scanned to obtain a matching range diagram of the automatic impedance matcher, including:

[0018] Keeping the capacitance of the first vacuum resistor at 0, gradually adjusting the capacitance of the second vacuum resistor, and scanning to obtain a first load value boundary;

[0019] Keeping the capacitance of the second vacuum resistor at 1, gradually adjusting the capacitance of the first vacuum resistor, and scanning to obtain a second load value boundary;

[0020] Keeping the capacitance of the first vacuum resistor at 1, gradually adjusting the capacitance of the second vacuum resistor, and scanning to obtain a third load value boundary;

[0021] Keeping the capacitance of the second vacuum resistor at 0, gradually adjusting the capacitance of the first vacuum resistor, and scanning to obtain a fourth load value boundary;

[0022] The first, second, third and fourth boundaries obtained by scanning are drawn to form a closed figure, and mapped to the Smith matching range map, to determine whether all points in the closed figure fall within the matching range of the Smith matching range map.

[0023] The beneficial effects of the present invention are:

[0024] The method adopted by the present invention can be applicable to the range measurement of automatic impedance matchers of different powers, frequencies and different structural designs. The actual automatic impedance matcher is measured without paying attention to the internal structure of the automatic impedance matcher. The method is closer to the actual use scenario, the measurement process is more efficient, and the measurement result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the reverse connection of a matcher provided in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the reverse connection logic of a matcher provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of a positive connection of a matcher provided in an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of impedance matching of a matching device provided in an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the impedance range under an ideal model provided by an embodiment of the present invention;

[0030] Figure 6 A schematic diagram of an actual test impedance range provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0032] The existing technology uses model derivation, impedance analysis or simulation software to determine the range, which is affected by the power size, chassis cavity structure design, internal components of the chassis, etc., and often cannot obtain the actual and comprehensive parameters of key components such as vacuum capacitors and inductors. In addition, parasitic capacitance and inductance will be generated in the actual circuit, resulting in deviations between the simulation results and the actual values. At the same time, when the internal structure of the automatic impedance matcher is complex, the complexity of the reasoning method increases geometrically, which is not suitable for the range measurement of automatic impedance matchers with more complex structures. The method adopted in this embodiment can be applied to the range measurement of automatic impedance matchers with different powers, frequencies, and different structural designs. It can measure the actual automatic impedance matcher without paying attention to the internal structure of the automatic impedance matcher, which is closer to the actual usage scenario, the measurement process is more efficient, and the measurement results are more accurate.

[0033] See also Figure 1-Figure 4 , this embodiment is implemented as follows:

[0034] Reverse the connection of the automatic impedance matcher (as an optional method, the automatic impedance matcher is an L-type automatic impedance matcher structure), connect the input end to a standard 50-ohm load, and connect the output end to an impedance detection instrument. At the same time, use an external signal source such as an RF power supply to generate a test signal.

[0035] like Figure 2 , assuming that the capacitance values ​​of the two vacuum capacitors of the current automatic impedance matcher (the maximum value is normalized to 1) are CL = 0.1 and CT = 0.5, and the current impedance value obtained by testing is ZL = r+xj.

[0036] like Figure 3 , then when the two capacitance values ​​of the automatic impedance matcher remain unchanged, when the automatic impedance matcher is connected in the forward direction, the load impedance on the right side of the load end should also be: r+x*j. According to the principle of impedance conjugate matching, when connected in the forward direction, a load with an impedance of rx*j is connected to the load end to achieve the impedance matching effect, that is, when CL = 0.1, CT = 0.5, the automatic impedance matcher can match the load with an impedance of rx*j, such as Figure 4 shown.

[0037] In an optional implementation scenario of the above scheme, when the automatic impedance matcher is reversely connected, a standard 50-ohm load is connected to the input end of the matcher, and the reverse impedance ZL=r+xj is measured at the load end of the automatic impedance matcher. While keeping the position of the above-mentioned matcher capacitor unchanged, the automatic impedance matcher is adjusted to be positively connected, then the impedance value of the whole composed of the matcher and the signal source with an internal resistance of 50 ohms should be the impedance ZL=r+xj measured above. If a load with an impedance ZX=r-xj is connected to its load end at this time, then ZX and ZL at this time have reached a conjugate matching state, that is, the load that the matcher can match in the current state is ZX=r-xj; wherein ZL is impedance, r is resistance, x is reactance, and j is an imaginary unit.

[0038] According to this principle, the values ​​of the two vacuum capacitors of the automatic impedance matcher can be combined arbitrarily in theory. Figure 1 The measured impedance value after taking the complex conjugate is all the load values ​​that the automatic impedance matcher can match, but this workload is too large. In fact, it is only necessary to scan the boundary value of the capacitor to get an area. Based on the rotatable nature of the capacitor, the scanning process is as follows:

[0039] CT:0, CL:0 ->1

[0040] CT:0 ->1, CL:1

[0041] CT:1, CL:1 ->0

[0042] CT:1 ->0, CL:0

[0043] The impedance in the closed area obtained by scanning is complex conjugated to obtain a matching range diagram of the automatic impedance matcher. All points in the closed area are within the matching range of the automatic impedance matcher, and the matching range test is now completed.

[0044] Compared with the prior art method of obtaining a theoretical matching range by performing impedance transformation through an automatic impedance matching model, the method of this embodiment is based on actual measured data and has higher accuracy. Figure 5, is the impedance range of the Smith matching range diagram (Smith matching range diagram, also called Smith diagram, also called Smith circle diagram, is a calculation diagram of a family of equal-value circles of normalized input impedance (or admittance) plotted on the complex plane of the reflection coefficient. It is mainly used for impedance matching to observe impedance changes and determine the specific impedance value by the intersection of equal resistance circles and equal reactance circles) under the ideal model of this embodiment. It is the derivation result of this embodiment. Taking the theoretical reasoning simulation as an example, the impedance range simulated and reasoned in the impedance transformation method is basically a square area. In the actual measurement process, affected by a series of external factors such as parasitic parameters, design structure, power size, test frequency, etc., the actual measurement results are far from the theoretical results. Please refer to Figure 6 , after actual test verification, the measurement method of this embodiment is closer to the actual matching range of the actual matcher.

[0045] Based on the above scheme, this embodiment can be applicable to the range measurement of automatic impedance matchers with different powers, frequencies, and different structural designs. It can measure the actual automatic impedance matcher without paying attention to the internal structure of the automatic impedance matcher. It is closer to the actual usage scenario, the measurement process is more efficient, and the measurement results are more accurate.

[0046] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for testing the matching range of a radio frequency automatic impedance matcher, characterized in that: include: Reverse the connection of the automatic impedance matcher so that its input end is connected to the load and its output end is connected to the impedance detector; connect an external RF signal source to one side of the impedance detector as the test signal input end; Respectively detecting the values ​​of the first vacuum capacitor and the second vacuum capacitor of the current automatic impedance matcher, and obtaining the impedance value of the current automatic impedance matcher; The values ​​of the first vacuum capacitor and the second vacuum capacitor are locked. When the automatic impedance matcher is reversely connected, a load is connected to the input end of the automatic impedance matcher, and a reverse impedance is measured at the load end of the automatic impedance matcher; the reverse impedance ZL=r+xj; While keeping the capacitor position of the automatic impedance matcher unchanged, adjusting the automatic impedance matcher to be in forward connection, and determining whether the overall impedance value composed of the automatic impedance matcher and the input-end signal source is equal to the reverse impedance measured above; If they are equal, connect the impedance conjugate impedance ZX at its load end to make the conjugate impedance ZX and the reverse impedance ZL form a conjugate match; where the conjugate impedance ZX=r-xj, r is the resistance, x is the reactance, and j is the imaginary unit; The value of any of the vacuum capacitors is changed, and the value within the boundary value interval is scanned to obtain a matching range diagram of the automatic impedance matcher.

2. A method for testing the matching range of a radio frequency automatic impedance matcher according to claim 1, characterized in that: Before testing, the maximum value of any of the vacuum capacitances was normalized to 1.

3. A method for testing the matching range of a radio frequency automatic impedance matcher according to claim 2, characterized in that: Changing the value of any of the vacuum capacitors, scanning the values ​​within the boundary value interval, and obtaining a matching range diagram of the automatic impedance matcher, including: Keeping the capacitance of the first vacuum resistor at 0, gradually adjusting the capacitance of the second vacuum resistor, and scanning to obtain a first load value boundary; Keeping the capacitance of the second vacuum resistor at 1, gradually adjusting the capacitance of the first vacuum resistor, and scanning to obtain a second load value boundary; Keeping the capacitance of the first vacuum resistor at 1, gradually adjusting the capacitance of the second vacuum resistor, and scanning to obtain a third load value boundary; Keeping the capacitance of the second vacuum resistor at 0, gradually adjusting the capacitance of the first vacuum resistor, and scanning to obtain a fourth load value boundary; The first, second, third and fourth boundaries obtained by scanning are drawn to form a closed figure, and mapped to the Smith matching range map to determine whether all points in the closed figure fall within the Smith matching range.

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