Apparatus for controlled overshoot in a RF generator
A radio-frequency (RF) generator is provided that produces a controlled overshoot. One embodiment includes a RF power amplifier and a direct-current (DC) power supply that includes a primary DC power supply, an auxiliary DC power supply, a half-bridge circuit, and a control circuit. The half-bridge circuit, in a first switching state, electrically connects, in series, the auxiliary DC power supply with the primary DC power supply and, in a second switching state, electrically disconnects the auxiliary DC power supply from the primary DC power supply. The control circuit places the half-bridge circuit in the first switching state for a first period of time and places the half-bridge circuit in the second switching state for a second period of time to produce a controlled overshoot in the power produced by the RF generator throughout the first period of time.
1. A radio-frequency (RF) generator, comprising:
a RF power amplifier; and
a direct-current (DC) power supply electrically connected with the RF power amplifier to supply electrical power to the RF power amplifier, the DC power supply including:
a primary DC power supply;
an auxiliary DC power supply;
a half-bridge circuit that, in a first switching state, applies power to the RF power amplifier by electrically connecting, in series, the auxiliary DC power supply with the primary DC power supply and that, in a second switching state, electrically disconnects the auxiliary DC power supply from the primary DC power supply while applying power from the primary DC power supply to the RF power amplifier; and
a control circuit that places the half-bridge circuit in the first switching state for a first period and that places the half-bridge circuit in the second switching state for a second period to produce a controlled overshoot in the power produced by the RF generator throughout the first period,
wherein the first period begins at a leading edge of a power pulse produced by the RF generator and the second period immediately follows the first period.
2. The RF generator of claim 1 , wherein the RF power amplifier is a balanced RF power amplifier.
3. The RF generator of claim 1 , wherein at least one of the primary DC power supply and the auxiliary DC power supply is variable.
4. The RF generator of claim 1 , wherein the RF generator directly or indirectly supplies power to a plasma load through one or more matching networks.
5. The RF generator of claim 1 , wherein the controlled overshoot in the power produced by the RF generator is used for plasma ignition.
6. The RF generator of claim 1 , wherein the first and second periods are followed by zero, one, or a plurality of additional periods during which the RF generator produces a different amount of power than during the first and second periods.
7. The RF generator of claim 1 , wherein the first, second, and any additional periods repeat in a predetermined pattern to form a pulse train.
8. The RF generator of claim 1 , wherein the control circuit is configured to determine the first period by observing a change in the properties of a load connected with an output of the RF generator.
9. A radio-frequency (RF) generator, comprising:
a RF power amplifier; and
a direct-current (DC) power supply electrically connected with the RF power amplifier to supply electrical power to the RF power amplifier, the DC power supply including:
a primary DC power supply;
an auxiliary DC power supply;
a half-bridge circuit that, in a first switching state, electrically connects, in series, the auxiliary DC power supply with the primary DC power supply and that, in a second switching state, electrically disconnects the auxiliary DC power supply from the primary DC power supply; and
a control circuit that includes a non-transitory, tangible, machine-readable medium encoded with instructions to perform a method, the method including:
placing the half-bridge circuit in the first switching state for a first period, beginning at a leading edge of a power pulse produced by the RF power amplifier, to produce, for plasma ignition, a controlled overshoot in the power produced by the RF generator throughout the first period; and
placing the half-bridge circuit in the second switching state for a second period, the second period immediately following the first period.
10. The RF generator of claim 9 , wherein the first and second periods are followed by zero, one, or a plurality of additional periods during which the RF generator produces a different amount of power than during the first and second periods.
11. The RF generator of claim 9 , wherein the first, second, and any additional periods repeat in a predetermined pattern to form a pulse train.
12. The RF generator of claim 9 , wherein the first period is fixed.
13. The RF generator of claim 9 , wherein the method further includes:
determining the first period by observing a change in the properties of a load connected with an output of the RF generator.
14. The RF generator of claim 9 , wherein the RF generator directly or indirectly supplies power to a plasma load through one or more matching networks and the controlled overshoot in the power produced by the RF generator is used for plasma ignition.
15. A radio-frequency (RF) generator, comprising:
means for amplifying RF power;
means for supplying direct-current (DC) power to the means for amplifying RF power, the means for supplying DC power including primary means for supplying DC power and auxiliary means for supplying DC power;
means for switching that, in a first switching state, electrically connects, in series, the auxiliary means for supplying DC power with the primary means for supplying DC power and that, in a second switching state, electrically disconnects the auxiliary means for supplying DC power from the primary means for supplying DC power; and
means for controlling the means for switching that places the means for switching in the first switching state for a first period, beginning at a leading edge of a power pulse produced by the means for amplifying RF power, and that places the means for switching in the second switching state for a second period, immediately following the first period, to produce, for plasma ignition, a controlled overshoot in the power produced by the RF generator throughout the first period.
16. The RF generator of claim 15 , wherein the means for controlling the means for switching is configured to cause the first and second periods to be followed by zero, one, or a plurality of additional periods during which the RF generator produces a different amount of power than during the first and second periods.
17. The RF generator of claim 15 , wherein the means for controlling the means for switching is configured to cause the first, second, and additional periods to repeat in a predetermined pattern to form a pulse train.
18. The RF generator of claim 15 , wherein the first period is fixed.
19. The RF generator of claim 15 , wherein the means for controlling the means for switching is configured to determine the first period by observing a change in the properties of a load connected to an output of the RF generator.
20. The RF generator of claim 15 , wherein the RF generator directly or indirectly supplies power to a plasma load through one or more matching networks.