Patent attributes
In one aspect, protecting high frequency (HF) amplifiers of a plasma supply device configured to deliver >500 W at a substantially constant fundamental frequency >3 MHz is accomplished by: driving two HF amplifiers with two drive signals having a common frequency and a predetermined phase shift with respect to one another; generating two HF source signals using the HF amplifiers, the HF source signals coupled in a coupler to form a HF output signal; transmitting the HF output signal to the plasma load; measuring electrical variables related to the load impedances seen by the two HF amplifiers; determining whether the load impedance seen by one of the HF amplifiers lies outside a predetermined range; and adjusting the phase shift of the two drive signals, wherein neither of the load impedances seen by the HF amplifiers lies outside the predetermined range.
