Multiple phase-locked loops for high-power RF-power combiners

1. Radio frequency (RF) power-supply apparatus for driving a gas-discharge laser, the apparatus comprising:

a reference oscillator generating an RF output at a first frequency;

a plurality of power-oscillators each thereof generating an RF output at a second common frequency, and each thereof phase-locked to the output frequency of the reference oscillator, each said power-oscillator including an oscillator and one or more stages of RF power amplification; and

a power combiner arranged to combine the outputs of the power oscillators into a single combined output for driving the gas-discharge laser.

2. The apparatus of claim 1 , wherein the second frequency is a harmonic of the first frequency.

3. The apparatus of claim 1 , wherein the oscillators of the power-oscillators are analog power oscillators including a voltage controlled oscillator (VCO).

4. The apparatus of claim 1 , wherein the oscillators of the power-oscillators are digital power-oscillators including a direct digital synthesizer (DDS).

5. The apparatus of claim 4 , wherein each of the power-oscillators includes switching means for selectively enabling and disabling the output thereof, the switching arrangements being simultaneously operable for providing that the combined output of the power-oscillators is in a pulsed form.

6. The apparatus of claim 5 , wherein the switching means includes an RF switch located between the DDS and the one or more amplification stages.

7. The apparatus of claim 6 , wherein the RF switches are simultaneously operable in response to a single common switch command signal.

8. A gas laser apparatus comprising:

a sealed housing containing a laser gas and a pair of discharge electrodes,

a radio frequency (RF) power-supply connected to the electrodes for generating a gas discharge within the housing, said power supply including:

a reference oscillator generating an RF output at a first frequency;

a plurality of power-oscillators each thereof generating an RF output at a second common frequency, each said power-oscillator including an oscillator and one or more stages of RF power amplification;

a power combiner arranged to combine the outputs of the power oscillators into a single combined output and electrically connected to the electrodes wherein each of the outputs of the power-oscillators is phase-locked to the output frequency of the reference oscillator.

9. The apparatus of claim 8 , wherein the second frequency is a harmonic of the first frequency.

10. The apparatus of claim 8 , wherein the oscillators of the power-oscillators are analog power oscillators including a voltage controlled oscillator (VCO).

11. The apparatus of claim 8 , wherein the oscillators of the power-oscillators are digital power-oscillators including a direct digital synthesizer (DDS).

12. The apparatus of claim 11 wherein the one or more stages of amplification include a driver amplifier feeding an even plurality of amplifier modules, with pairs of the modules connected in parallel in a push-pulse mode, and with the push-pull pairs of modules also being connected in parallel.

13. The apparatus of claim 11 , wherein each of the power-oscillators includes switching means for selectively enabling and disabling the output thereof, the switching arrangements being simultaneously operable for providing that the combined output of the power-oscillators is in a pulsed form.

14. The apparatus of claim 13 , wherein the switching means includes an RF switch located between the DDS and the one or more amplification stages.

15. The apparatus of claim 14 , wherein the RF switches are simultaneously operable in response to a single common switch command signal.