Impedance matching device provided with reactance-impedance table

• US 6,946,847 B2
• Filed: 01/30/2003
• Issued: 09/20/2005
• Est. Priority Date: 02/08/2002
• Status: Active Grant

• Current Assignee: Daihen Corporation
• Original Assignee: Daihen Corporation
• Inventors: Nishimori, Yasuhiro, Ishida, Yuji, Omae, Shuji, Mito, Masakatsu, Itadani, Koji
• Primary Examiner(s): Nguyen, Vincent Q.
• Assistant Examiner(s): Nguyen, Hoai-An D.
• Application Number:
  US10/355,979
• Publication Number:
  US 20030184319A1
• Time in Patent Office: 964 Days
• Field of Search: 333/124, 333/17.3, 333/32, 702/107, 324/158.1, 324/520, 324/525, 324/754, 324/755, 324/761, 324/176, 324/76.58, 324/600, 324/684, 324/464, 324/649, 324/691, 324/637, 324/76.19
• US Class Current: 324/600
• CPC Class Codes: H03H 11/30 Automatic matching of source impedance to load impedance

Abstract

An impedance matching device is provided, for which the electric characteristics at an output terminal are accurately analyzed. The matching device is provided with an input detector for detecting RF voltage and current at the input terminal, and an output detector for detecting RF voltage outputted from the output terminal. The matching device also includes a controller for achieving impedance matching between a high frequency power source connected to the input terminal and a load connected to the output terminal. The impedance matching is performed by adjusting variable capacitors based on the detection data supplied from the input detector. When the impedance of the power source is matched to that of the load, the controller calculates the output impedance, RF voltage and RF current at the output terminal, based on the adjusted capacitances of the capacitors, a pre-obtained reactance-impedance data and the detection data supplied from the output detector.

Claims

1. An impedance matching device comprising:

an input terminal connect to a high frequency power source;

an output terminal connected to a load;

a reactance circuit including at least one variable reactor, the circuit arranged between the input terminal and the output terminal;

an input detector that detects voltage and current of high frequency power inputted to the input terminal;

a matching controller that matches impedance of the power source and impedance of the load by adjusting reactance of the variable reactor based on data detected by the input detector; and

an analyzer that analyzes electric characteristics at the output terminal based on both data about the adjusted reactance of the variable reactor and a pre-obtained reactance-impedance data-when the impedance of the power source and the impedance of the load are matched to each other;

wherein the reactance-impedance data represents relations between data on a plurality of preselected reactances of the variable reactor and impedance data at the output terminal, the reactance-impedance data being produced with the input terminal connected to the power source or an equivalent of the power source before the output terminal is connected to the load.

2. The matching device according to claim 1, further comprising a storage that stores the reactance-impedance data.

3. The matching device according to claim 1, further comprising an input section for input of the reactance impedance data when the reactance-impedance data is externally supplied.

4. The matching device according to claim 1, further comprising an output section for output of the electric characteristics analyzed by the analyzer.

5. The matching device according to claim 1, further comprising an interpolation calculator for producing interpolation data by interpolation based on the reactance-impedance data, the interpolation data representing relations between data on reactances of the variable reactor and impedance at the output terminal, wherein the analyzer performs the analysis of the electric characteristics at the output terminal based on said adjusted reactance and either one of the reactance-impedance data and the interpolation data.

6. The matching device according to claim 1, wherein the analyzer calculates impedance as the electric characteristics at the output terminal.

7. The matching device according to claim 6, wherein the analyzer calculates, based on said calculated impedance and detection suits by the input detector, high frequency voltage or high frequency current as the electric characteristics at the output terminal.

8. The matching device according to claim 6, wherein the analyzer calculates, based on said calculated impedance, a phase difference between the high frequency voltage and the high frequency current at he output terminal, the analyzer further calculating, based on the high frequency voltage an the high frequency current detected by the input detector, input power at the input terminal, the analyzer further calculating, based on the input power and said calculated impedance, high frequency voltage or high frequency current at the output terminal on an assumption that the input power is transmitted to the output terminal without loss.

9. The matching device according to claim 1, further comprising an actuator for changing the reactance of the variable reactor, wherein the reactance-impedance data includes information about relations between a position of a movable member of the actuator and the impedance at the output terminal.

10. The matching device according to claim 1, wherein the impedance data included in the reactance-impedance data comprises impedance measured as viewed from the output terminal toward the power source.

11. The matching device according to claim 10, wherein the impedance data is obtained by measuring output impedance of the marching device using an impedance measuring device as the reactance of the variable reactor is changed, with the input terminal connected to a dummy load and the output terminal connected to the impedance measuring device.

12. The matching device according to claim 11, further comprising an interpolation calculator that produces output impedance interpolation data by interpolation using the output impedance measured by the impedance measuring device.

13. The matching device according to claim 12, wherein the interpolation includes proportional operation using the output impedance measured by the impedance measuring device.

14. The matching device according to claim 1, wherein the impedance data included in the reactance-impedance data comprises impedance measured as viewed from the output terminal toward the load.

15. The matching device according to claim 14, wherein the impedance data is obtained by connecting the power source to the input terminal via a power meter, connecting a variable dummy load to the output terminal, causing the power source to supply high frequency electric power, adjusting the variable dummy load so that electric power of a reflected wave is minimized for a given reactance of the variable reactor, and measuring the adjusted impedance of the dummy load by an impedance measuring device.

16. The matching device according to claim 15, further comprising an interpolation calculator for producing impedance interpolation data by interpolation based on the impedance measured by the impedance measuring device.

17. The matching device according to claim 1, further comprising an output detector for detecting either one of high frequency voltage and high frequency current outputted to the load from the output terminal, wherein the analyzer performs the analysis of the electric characteristics at the output terminal based on the data about said adjusted reactance, the reactance-impedance data and detection results by the output detector.

18. The matching device according to claim 17, further comprising an interpolation calculator that produces interpolation data representing relations between data on the reactance of the variable reactor and impedance data at the output terminal, the interpolation data being obtained by interpolation using the reactance-impedance data, wherein the analyzer performs the analysis of the electric characteristics at the output terminal based on detection results from the data on said adjusted reactance and either one of the reactance-impedance data and the interpolation data.

19. The matching device according to claim 17, further comprising an actuator for changing the reactance of the variable reactor, therein the reactance-impedance data includes information about relations between a position of a movable member of the actuator and the impedance at the output terminal.

20. The matching device according to claim 17, wherein the analyzer calculates impedance at the output terminal based on data about said adjusted reactance and the reactance-impedance data, the analyzer further calculating a phase difference between high frequency voltage and high frequency current at the output terminal based on the calculated impedance, the analyzer her calculating, based on the calculated phase difference, the calculated impedance and either one of the high frequency voltage and current detected by the output detector, the remaining one of the high frequency voltage and current.

21. The matching device according to claim 18, wherein the analyzer calculates impedance at the output terminal based on data about said adjusted reactance and either one of the reactance-impedance data and the interpolation data, the analyzer further calculating a phase difference between high frequency voltage and high frequency current at the output terminal based on the calculated impedance, the analyzer further calculating, based on the calculated phase difference, the calculated impedance and either one of the high frequency voltage and current detected by the output detector, the remaining one of the high frequency voltage and current.

22. An impedance matching system comprising an impedance matching unit and an output characteristics analyzing unit,

wherein the matching unit includes:

an input terminal connected to a high frequency power source;

an output terminal connected to a load;

at least one variable reactor arranged between the input terminal and the output terminal for matching impedances of the power source and the load;

an input detector that detects voltage and current of high frequency power supplied from the power source; and

a matching controller that matches the impedance of the power source and the impedance of the load by adjusting reactance of the variable reactor based on detection data from the input detector; and

wherein the analyzing unit includes;

a storage that stores reactance-impedance data representing relations between data on a plurality of preselected reactances of the variable reactor and data on impedance at the output terminal, the reactance-impedance data being produced with the input terminal connected to the power source or an equivalent of the power source before the output terminal is connected to the load; and

an analyzer that analyzes electric characteristics at the output terminal based on both data about the reactance adjusted by the matching controller and the reactance-impedance data.

23. The system according to claim 22, wherein the analyzer of the analyzing unit performs the analysis of the electric characteristics at the output terminal based on data on the reactance adjusted by the matching controller, detection results from the input detector and the reactance-impedance data.

24. The system according to claim 22, further comprising an output detector arranged in the impedance matching unit for detecting either one of high frequency voltage and high frequency current outputted from the output terminal to the load.

25. The system according to claim 24, wherein the analyzer of the analyzing unit performs the analysis of the electric characteristics at the output terminal based on data on reactance adjusted by the matching controller, detection results from the output detector and the reactance-impedance data.

26. The system according to claim 22, wherein the electric characteristics at the output terminal includes at least one of output impedance of the matching unit, impedance of the load, high frequency voltage at the output terminal and high frequency current at the output terminal.

27. The system according to claim 22, further comprising a display arranged in the analyzing unit for visually presenting analysis data supplied from the analyzer.

28. A method of analyzing electric characteristics at an output terminal of an impedance matching device provide with an input terminal and a variable reactor arranged between the input terminal and the output terminal, the method comprising:

producing reactance-impedance data while the input terminal is connected to a high frequency power source or an equivalent of the power source and before the output terminal is connected to a load, the reactance-impedance data representing relations between data on a plurality of preselected reactances of the variable reactor and data on impedance at the output terminal,

supplying high frequency electric power to the input terminal while the input terminal is connected to the power source and the output terminal is connected to the load,

detecting high frequency voltage and high frequency current at the input terminal,

adjusting reactance of the variable reactor based on data on the detected high frequency voltage and current, so at the impedance of the power source and the impedance of the load are matched to each other, and

analyzing the electric characteristics at the output terminal by using data on the adjusted reactance and the reactance-impedance data.

29. The method according to claim 28, wherein the analysis of the electric characteristics at the output terminal is performed based on data on the high frequency voltage and current detected at the input terminal, data on the adjusted reactance and the reactance-impedance data.

30. The method according to claim 28, further comprising detecting either one of high frequency voltage and high frequency current at the output terminal, wherein the analysis of the electric characteristics at the output terminal is performed based on detection data at the output terminal, data on the adjusted reactance and the reactance-impedance data.