Abstract: A single stage amplifier system that produces an accurate linear output signal during low power demands and a pulse modulated output signal during high power demands is disclosed. A control circuit provides a linear signal and a pulsed signal to an output stage in response to a select signal provided by an external circuit. The single output stage includes two transistors in a push-pull arrangement that can be driven in their saturation regions when a pulsed signal is provided by the control circuit or driven within their linear region when a linear signal is provided. The single stage amplifier system can be used in either a half bridge amplifier system or an H-bridge amplifier system.

Abstract: A highly linear, low-distortion H-bridge amplifier is described. The amplifier includes four interconnected power transistors connected to an inductive load. Each transistor has a precision voltage clamp connected between the source and drain to suppress ringing oscillations. Two or more of the transistors also include high-speed transient-voltage suppressers connected in parallel with their respective voltage clamps. These transient-voltage suppressers do not have the clamping accuracy of the voltage clamps, but respond much more quickly to suppress noise spikes. The amplifier therefore takes advantage of both the fast response time of the transient-voltage suppressers and the precise voltage-clamping characteristics of the voltage clamps.

Abstract: A high-power PWM system with improved low-power performance and which includes an oscillator configured to provide a substantially periodic signal to a pulse-width modulator. The pulse-width modulator outputs a PWM signal, derived from the analog signal and the periodic signal, on the PWM output node to a high-power amplifier that can select from a number of power-supply voltages. The PWM system improves amplification accuracy at low input signal levels by selecting a reduced power-supply voltage. The pulse width of the PWM signal is increased proportional to the decrease in the power-supply voltage to maintain the gain factor of the system at low power.

Abstract: The invention comprises a platform positionable in at least three degrees of freedom at least partly by interaction with coils. The platform includes a support member having a surface. Magnets are attached to the surface and part of a magnet bearing is attached to the support member. Inner and outer platforms are coupled to each other by magnet bearings and interact with coils to position the inner platform in six degrees of freedom. The invention may be particularly useful in precise positioning of semiconductor wafers and materials during photolithography and other processing.

Abstract: A high performance pulse width modulation amplifier system employing an H-bridge amplifier connected to a carrier wave output filter produces a pulsed wave signal with high power transfer efficiency and low total harmonic distortion characteristics. A carrier wave output filter used with the pulse width modulation amplifier system produces little peak resonance at low frequencies.

Abstract: A linear amplifier provides an output signal that is proportional to an input signal. A differential voltage control unit tracks the output signal voltage and controls the outputs of two pulse width modulators which drive a linear amplifier. The differential voltage control unit controls the output of the positive pulse width modulator to a fixed predetermined value in accordance with at least one of the input or output signals. The positive and negative pulse width modulators are driven by a positive and negative high voltage direct current power supplies respectively.

Abstract: A transadmittance amplifier provides an output current that is proportional to an input voltage level. The output current drives a coil of an electric motor (the load) through a sense resistor, the voltage drop across the sense resistor providing an indication of the amount of current flowing through the coil. The indication provided by the sense resistor is applied across the differential input terminals of a feedback amplifier, which responds by outputting a feedback signal proportional to the output current. In one embodiment, the maximum output current is increased by providing a pair of complementary drive amplifiers.