RF match detector circuit with dual directional coupler

A RF matching circuit for matching an RF power source to a load, said RF matching circuit comprising:

• an RF match section connected to the load;
• and
• a detector circuit connected between said RF source and said RF match section,
• said RF match section comprising:
• a first variable reactance element;
• a second variable reactance element;
• a first control circuit controlling the reactance of the first variable reactance element in response to a first control signal;
• and
• a second control circuit controlling the reactance of the second variable reactance element in response to a second control signal;
• said detector circuit comprising:
• a dual directional coupler having an input for connecting to the RF source and an output connected to the RF match section, said dual directional coupler generating a forward signal and a reflected signal, said forward signal being proportional to RF power delivered to the RF match section and said reflected signal being proportional to RF power reflected back from the RF match section;
• a first branch circuit receiving the reflected signal and producing a first and second output signal therefrom;
• a second branch circuit receiving the forward signal and producing a first and second output signal therefrom;
• a first phase detector receiving the first output signals of the first and second branch circuits and generating a first phase detection output signal from which said first control signal is derived;
• and
• a second phase detector receiving the second output signals of the first and second branch circuits and generating a second phase detection output signal from which said second control signal is derived.

A plasma processing system comprising:

• a plasma chamber;
• an RF matching circuit for matching an RF power source to said plasma chamber, said RF matching circuit comprising:
• an RF match section connected to the plasma chamber;
• and
• a detector circuit connected between said RF power source and said RF match section,
• said RF match section comprising:
• a first variable reactance element;
• a second variable reactance element;
• a first control circuit controlling the reactance of the first variable reactance element in response to a first control signal;
• and
• a second control circuit controlling the reactance of the second variable reactance element in response to a second control signal;
• said detector circuit comprising:
• a dual directional coupler having an input for connecting to the RF source and an output for connecting to the RF match circuit, said dual directional coupler generating a forward signal and a reflected signal, said forward signal being proportional to RF power delivered to the match circuit and said reflected signal being proportional to RF power reflected back from the RF match circuit;
• a first branch circuit receiving the reflected signal and producing a first and second output signal therefrom;
• a second branch circuit receiving the forward signal and producing a first and second output signal therefrom;
• a first phase detector receiving the first output signals of the first and second branch circuits and generating a first phase detection output signal from which said first control signal is derived;
• and
• a second phase detector receiving the second output signals of the first and second branch circuits and generating a second phase detection signal from which said second control signal is derived.