Inductively-Coupled RF Power Source

• US 20090058304A1
• Filed: 11/06/2008
• Published: 03/05/2009
• Est. Priority Date: 11/21/2005
• Status: Active Grant

• Current Assignee: Thermo Electron Manufacturing Limited (Thermo Fisher Scientific Incorporated)
• Original Assignee: Paul J. Mattaboni, Robert Mellor, Roger Fletcher
• Inventors: Fletcher, Roger, Mellor, Robert, MATTABONI, Paul J.
• Granted Patent: US 7,940,008 B2
• Time in Patent Office: Days
• US Class Current: 315/111.210
• CPC Class Codes: G01N 21/73 using plasma burners or torches
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H03L 5/02 of power
• CPC Class Codes: H03L 7/06 using a reference signal applied to a frequency- or phase-locked loop
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

A system and method are disclosed for implementing a power source including a power amplifier that generates a radio-frequency power signal with an adjustable operating frequency. The power amplifier also generates a reference phase signal that is derived from the radio-frequency power signal. An impedance match provides the radio-frequency power signal to a plasma coil that has a variable resonance condition. A phase probe is positioned adjacent to the plasma coil to generate a coil phase signal corresponding to the adjustable operating frequency. A phase-locked loop then generates an RF drive signal that is based upon a phase relationship between the reference phase signal and the coil phase signal. The phase-locked loop provides the RF drive signal to the power amplifier to control the adjustable operating frequency, so that the adjustable operating frequency then tracks the variable resonance condition.

Claims

1. A system for implementing a power source, comprising:

a power amplifier that generates a radio-frequency power signal with an adjustable operating frequency, said power amplifier also generating a reference phase signal derived from said radio-frequency power signal;

an impedance match that provides said radio-frequency power signal to a plasma coil that has a variable resonance condition;

a phase probe positioned adjacent to said plasma coil to generate a coil phase signal corresponding to said adjustable operating frequency; and

a phase-locked loop device that generates a drive signal to said power amplifier to control said adjustable operating frequency, said drive signal being based upon a phase relationship between said reference phase signal and said coil phase signal, said adjustable operating frequency then tracking said variable resonance condition.