Ripple cancellation circuit for ultra-low-noise power supplies

Abstract

A low-ripple power supply includes a storage capacitor coupled across load terminals, and an inductor connected to a source of voltage including a varying or pulsatory component and a direct component, for causing a flow of current to said capacitor through the inductor. The varying component of the inductor current flowing in the capacitor results in ripple across the load. A winding is coupled to the inductor for generating a surrogate of the varying inductor current. The surrogate current is added to the inductor current to cancel or reduce the magnitude of the varying current component. This cancellation effectively reduces the varying current component flowing in the storage capacitor, which in turn reduces the ripple appearing across the load terminals.(121)

Description

FIELD OF THE INVENTION[0001]This invention relates to direct-voltage power supplies, and more particularly to low-noise or low-ripple power supplies.BACKGROUND OF THE INVENTION[0002]Much of the advance in standard of living over the past twenty or so years results from the use of advanced communications, data processing, and environmental sensing techniques. The devices used in such communications, processing, and sensing generally become more useful as their sizes are decreased, such that more of them can be used. For example, computers and cellular phones require ever-smaller elements, and become more capable as the number of devices which can be accommodated increases. Similarly, lightweight and reliable sensors can be used in large numbers in vehicles to aid in control and, in the case of spacecraft and military vehicles, to aid in carrying out their missions.[0003]Most modern semiconductor devices, and other devices important for the above purposes, are generally energized or b...

AI Technical Summary

Problems solved by technology

Unfortunately, a concomitant of low power requirements is often sensitivity to unintended noise or fluctuations in the applied power.

It is less apparent but true that small-percentage variations or noise on the applied powering voltage may result in degradation of the operating characteristics of semiconductor and other devices and the circuits in which they operate, which may adversely affect the performance.

However, transformers operating at 60 Hz tend to be much larger than is desirable in modern miniaturized equipment.

However, batteries have the same general problem as that of mains powering, namely that available direct voltage does not necessarily correspond with the desired operating voltage.

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