Reference Box for Direct-Drive Radiofrequency Power Supply

A radiofrequency calibration system, comprising:

• a reference box including a reference circuit configured to convert a non-reference input impedance to a reference output impedance, the reference box having an input connector and an output connector, the input connector configured to electrically connect with a radiofrequency output coupling of a direct-drive radiofrequency power supply;
• a radiofrequency power meter having a radiofrequency power input electrically connected to the output connector of the reference box, the radiofrequency power meter having a radiofrequency power output and a data interface, the radiofrequency power meter having a reference input impedance and a reference output impedance substantially equal to the reference output impedance of the reference box;
• a cable having an impedance substantially equal to the reference output impedance of the reference box, the cable having a first end electrically connected to the radiofrequency power output of the radiofrequency power meter, the cable having a second end;
• a test load electrically connected to the second end of the cable, the test load having an impedance substantially equal to the reference output impedance of the reference box;
• and
• a controller connected in data communication with the data interface of the radiofrequency power meter.

A method for calibrating a direct-drive radiofrequency power supply, comprising:

• (a) electrically disconnecting a radiofrequency power output of the direct-drive radiofrequency power supply from a downstream radiofrequency power transmission system;
• (b) electrically connecting an input connector of a reference box to the radiofrequency power output of the direct-drive radiofrequency power supply, the reference box including a reference circuit configured to convert a non-reference input impedance to a reference output impedance;
• (c) electrically connecting an output of the reference box to an input of a radiofrequency power meter, the radiofrequency power meter having an output electrically connected through a cable to a test load;
• (d) operating the direct-drive radiofrequency power supply to drive a setpoint amount of radiofrequency power through the reference box, power meter, and cable to the test load;
• (e) operating the radiofrequency power meter to measure an output amount of radiofrequency power at the output of the reference box;
• (f) adjusting the output amount of radiofrequency power measured by the radiofrequency power meter by a known amount of radiofrequency power dissipated by the reference box to determine an actual output amount of radiofrequency power;
• and
• (g) storing the actual output amount of radiofrequency power in relation to the setpoint amount of radiofrequency power as a radiofrequency power calibration datapoint for the direct-drive radiofrequency power supply, a difference between the actual output amount of radiofrequency power and the setpoint amount of radiofrequency power providing a radiofrequency power calibration adjustment factor to ensure that the radiofrequency power output of the direct-drive radiofrequency power supply substantially matches the setpoint amount of radiofrequency power during operation of the direct-drive radiofrequency power supply.