Patent ID: 8421377
Filing Date: 2013-04-16
Classification: G01R,H01J,H02M,H03H,H05B,H05H,Y02B

Abstract:
1. A method of protecting high-frequency amplifiers of a plasma supply device configured to deliver a high-frequency output signal having a power of more than 500 W and a substantially constant fundamental frequency greater than 3 MHz to a plasma load, the method comprising: driving two high frequency amplifiers with two drive signals having a common frequency and a predetermined phase shift with respect to one another; generating two high frequency source signals using the two high frequency amplifiers, the two high frequency source signals being coupled in a coupler to form a combined high frequency output signal; transmitting the combined high frequency output signal to the plasma load; measuring electrical variables related to load impedances seen by the two high frequency amplifiers; determining load impedances seen by the two high frequency amplifiers; and in response to determining that the load impedance seen by one of the two high frequency amplifiers lies outside a predetermined range, adjusting the phase shift of the two drive signals sufficiently to cause a phase shift of the high frequency source signals with respect to one another, the phase shift of the high frequency source signals causing the load impedances seen by the two high frequency amplifiers to lie within the predetermined range.