# US 2014/0155008 A1 · Frequency tuning system and method for finding a global optimum > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0155008 A1 - Document ID: US20140155008A1 - Status: Published application - Kind: A1 - Application number: 14/094,520 - Filed: 2013-12-02 - Published: 2014-06-05 - Earliest claimed: 2012-12-04 - Assignees: Advanced Energy Industries, Inc. - Applicants: Advanced Energy Industries, Inc. - Inventors: Gideon Van Zyl - Web page: https://patentgrep.com/patent/US20140155008A1 ## CPC - H01J 37/32155: {Frequency modulation} - G04F 5/14: using atomic clocks - H01J 37/32082: {Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence)} - H01J 37/32183: {Matching circuits} - H01J 37/32917: {Plasma diagnostics} - H01J 37/3299: {Feedback systems} - H03F 1/56: Modifications of input or output impedances, not otherwise provided for - H03F 3/189: High-frequency amplifiers, e.g. radio frequency amplifiers - H03F 3/24: of transmitter output stages - H03L 1/00: Stabilisation of generator output against variations of physical values, e.g. power supply - H03L 7/26: using energy levels of molecules, atoms, or subatomic particles as a frequency reference - H03F 2200/451: the amplifier being a radio frequency amplifier - H05H 2242/26: Matching networks - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) - H03F: AMPLIFIERS - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) - H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS ## Abstract A generator and method for tuning the generator are disclosed. The method includes setting the frequency of power applied by the generator to a current best frequency and sensing a characteristic of the power applied by the generator. A current best error based upon the characteristic of the power is determined, and the frequency of the power at the current best frequency is maintained for a main-time-period. The frequency of the power is then changed to a probe frequency and maintained at the probe frequency for a probe-time-period, which is less than the main-time-period. The current best frequency is set to the probe frequency if the error at the probe frequency is less than the error at the current best frequency. ## Claims ### Claim 1 A method for tuning a generator, the method comprising: setting the frequency of power applied by the generator to a current best frequency; sensing a characteristic of the power applied by the generator; determining a current best error based upon the characteristic of the power; maintaining the frequency of the power at the current best frequency for a main-time-period; changing the frequency of the power to a probe frequency; maintaining the frequency of the power at the probe frequency for a probe-time-period, wherein the probe-time-period is less than the main-time-period; setting the current best frequency to the probe frequency if the error at the probe frequency is less than the error at the current best frequency. ### Claim 2 (depends on 1) The method of claim 1, wherein the error is a measure of how close an impedance presented to the generator is to a desired impedance. ### Claim 3 (depends on 2) The method of claim 2, wherein the error is a load reflection coefficient magnitude calculated with respect to a desired impedance. ### Claim 4 (depends on 3) The method of claim 3, wherein the desired impedance is 50Ω. ### Claim 5 (depends on 1) The method of claim 1, wherein the power applied by the generator is applied to a plasma load. ### Claim 6 (depends on 1) The method of claim 1, wherein the probe-time-period is less than 100 microseconds. ### Claim 7 (depends on 1) The method of claim 1, wherein the probe-time-period is less than ten percent of the main period of time. ### Claim 8 (depends on 1) The method of claim 1 including matching a source impedance of the generator with a nominal load impedance. ### Claim 9 A generator comprising: a controllable signal generator to generate a frequency in response to a frequency control signal; a power amplifier to generate power at the generated frequency; an output line coupled to the power amplifier a sensor coupled to the power amplifier, the sensor generates an output signal indicative of an impedance presented to the power amplifier; a controller that is coupled to the sensor and the controllable frequency driver, the controller provides the frequency control signal to the controllable signal generator in response to the output signal indicative of the impedance presented to the power amplifier, the controller including a processor and a non-transitory, tangible computer readable storage medium encoded with processor readable instructions for adjusting the frequency control signal, the instructions including instructions to: setting the frequency control signal to a current best level so the frequency driver generates a current best frequency; determining a current best error based upon the output signal from the sensor; maintaining the frequency control signal at the current best level for a main-time-period; changing the frequency control signal to a probe level so the signal generator generates a probe frequency; maintaining the frequency control signal at the probe level so the signal generator maintains the probe frequency for a probe-time-period, wherein the probe-time-period is less than the main-time-period; setting the current best frequency to the probe frequency if the error at the probe frequency is less than the error at the current best frequency. ### Claim 10 (depends on 9) The generator of claim 9, wherein the error is a measure of how close the impedance presented to the generator is a desired impedance. ### Claim 11 (depends on 10) The generator of claim 10, wherein the error is a load reflection coefficient magnitude. ### Claim 12 (depends on 11) The generator of claim 11, wherein the load reflection coefficient magnitude is calculated with respect to an impedance of 50Ω. ### Claim 13 (depends on 9) The generator of claim 9, wherein the probe-time-period is less than 100 microseconds. ### Claim 14 (depends on 9) The generator of claim 9, wherein the probe-time-period is less than ten percent of the main-time-period. ### Claim 15 (depends on 9) The generator of claim 9, wherein the power amplifier includes a balanced amplifier.