A DC to DC converter which maintains high efficiency over broad current ranges in a current mode switching regulator circuit without changing operational mode. A low ripple voltage is maintained over the entire load range and good voltage regulation is maintained with high efficiency. This is possible because the switching frequency is adjusted in accordance with the load without changing operational states, thus making it unnecessary to define plural states of operation. The timing of turning on the switch(es) varies since the switch(es) is (are) turned on when two set (ready) signals both become ready. For fixed frequency switching applications, switching pulses from a fixed frequency oscillator as a first set signal are skipped when a second set signal is not ready. On the other hand, for a variable frequency switching scheme which is implemented by driving the switching with a one-shot having a constant OFF time, the switching pulse is created after both set signals become active. A low pass filter is also used to dynamically adjust the minimum peak inductor current and to minimize ripple voltage for low load conditions so that a smaller output capacitor may be used.

DC to DC converter with high efficiency for light loads

A toroidal plasma source (28) within a substrate processing chamber (10). The toroidal plasma source forms a poloidal plasma with theta symmetry. The poloidal plasma current is essentially parallel to a surface of the plasma generating structure, thus reducing sputtering erosion of the inner walls. The plasma current is similarly essentially parallel to a process surface (32) of a substrate (34) within the chamber. In a further embodiment, a shaped member (66) between the substrate and the plasma source controls the plasma density in a selected fashion to enhance plasma processing uniformity.

Toroidal plasma source for plasma processing

A quasi-resonant converter is disclosed as comprising a power source, a load and a resonant switch circuit for periodically connecting the power source to the load The resonant switch circuit includes a switch for connecting the power source to the load and for disconnecting the power source from the load, and a resonant circuit comprised of a resonant capacitor and a resonant inductor The switch is operated at a switching frequency in excess of 1 MHz and in the order of 10 to 20 MHz or greater The resonant circuit is connected to the switch to impose thereon a voltage waveform as developed across the resonant capacitor The resonant capacitor and the resonant inductor have respective impedances selected to shape the voltage waveform such that a zero-voltage condition is imposed upon the switch when it is disposed to its on state, whereby the parasitic capacitive losses associated with the switch are eliminated

Zero-voltage switching quasi-resonant converters

A transformer-coupled plasma source using toroidal cores forms a plasma with a high-density of ions along the center axis of the torus. In one embodiment, cores of a plasma generator are stacked in a vertical alignment to enhance the directionality of the plasma and generation efficiency. In another embodiment, cores are arranged in a lateral array into a plasma generating plate that can be scaled to accommodate substrates of various sizes, including very large substrates. The symmetry of the plasma attained allows simultaneous processing of two substrates, one on either side of the plasma generator.

Multi-core transformer plasma source

A family of quasi-resonant converters for providing regulated power is disclosed as comprising a voltage source, a load and a resonant switch circuit, for periodically connecting the voltage source to the load. The resonant switch circuit includes a switch, and a resonant circuit comprised of a resonant capacitor and a resonant inductor. The switch is actuated to its first state to permit a current flow in a first direction from the voltage source to the load and to block a current flow in a second, opposite direction, and deactuated to a second state to permit a current flow in the second direction from the load to the voltage source and to block the current flow in the first direction, whereby the quasi-resonant converter is operative in a full-wave mode. More specifically, the switch in its first state couples the resonant capacitor and the resonant inductor together to form a resonant switch circuit. The impedances of the resonant capacitor and the resonant inductor are selected to establish a resonating current waveform on the resonant inductor to apply zero-current conditions to the switch at turn on and turn off.

Zero-current switching quasi-resonant converters operating in a full-wave mode

A power supply for driving an inductive load current from a dc power supplyhrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

George R. Dyer

Papers

DC switching regulated power supply for driving an inductive load