Invention Grant
US5646561A High performance current switch for borehole logging tools 失效
用于钻孔测井工具的高性能电流开关

High performance current switch for borehole logging tools
Abstract:
A current switch for borehole logging tools operating at high temperatures with high load currents, which includes a driver unit that responds to an input digital control signal by holding an output field effect transistor in a turn-off state until its gate electrode is fully charged before allowing the transistor to supply current to an inductive or acoustic load, and by effecting a rapid discharge of the gate electrode to turn the transistor off. A digital coupler is inserted between the source of the input digital control signal and the driver unit to electrically decouple the load current from the source. The effects of spurious noise contaminants including power spikes in the load, fly-back coupling, and Miller's capacitance thereby are minimized and a switching action with minimal transition time is achieved. The current switch is particularly adaptable for use in a complementary-symmetric circuit for a bi-directional switch that causes current to flow first in one direction, and then in the opposite direction through the load with minimal cross propagation of noise.
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