Wide frequency band coupling network for an active ripple and noise filter
First Claim
1. A filter for filtering ripple and noise voltages from a DC voltage, said filter comprising:
- a common terminal, an input terminal and an output terminal;
voltage sensing means for producing a sense signal which is proportional to an output voltage at said output terminal;
an active filtering circuit having an input for receiving said sense signal and an output terminal, said active filtering circuit being adapted to generate at said output terminal of said circuit a correction signal having a magnituide and waveform such that coupling said correction signal onto said output terminal of said filter tends to reduce said ripple and noise voltages;
a passive coupling element connected between said output terminal of said active filtering circuit and said output terminal of said filter; and
a passive filter element connected between said output terminal and said common terminal of said filter, said passive coupling element and said passive filter element having nearly identical electrical characteristics.
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Accused Products
Abstract
A ripple and noise filter for high voltage DC converters or power supplies. The filter includes a common terminal, an input terminal and an output terminal. A voltage sensing circuit is connected between the output and common terminals of the filter and is adapted to produce a sense signal which is proportional to the output voltage at the output terminal. An active filtering circuit, preferably an amplifier having a frequency operating range which covers the frequency spectrum of the ripple and noise voltages, includes an input for receiving the sense signal and an output at which a correction signal is generated. The correction signal has a magnitude and waveform such that coupling the correction signal onto the output terminal of the filter eliminates or reduces the ripple and noise. A passive coupling element, preferably a capacitor, isolates the amplifier from the output terminal and couples the correction signal thereto. A passive filter, also a capacitor, is connected across the output and common terminals of the filter. The coupling capacitor and the passive filter capacitor have nearly identical electrical characteristics so that the correction signal is coupled onto the output terminal without distortion over the full frequency operating range of the amplifier.
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Citations
14 Claims
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1. A filter for filtering ripple and noise voltages from a DC voltage, said filter comprising:
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a common terminal, an input terminal and an output terminal; voltage sensing means for producing a sense signal which is proportional to an output voltage at said output terminal; an active filtering circuit having an input for receiving said sense signal and an output terminal, said active filtering circuit being adapted to generate at said output terminal of said circuit a correction signal having a magnituide and waveform such that coupling said correction signal onto said output terminal of said filter tends to reduce said ripple and noise voltages; a passive coupling element connected between said output terminal of said active filtering circuit and said output terminal of said filter; and a passive filter element connected between said output terminal and said common terminal of said filter, said passive coupling element and said passive filter element having nearly identical electrical characteristics. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A ripple and noise filter for filtering a high voltage DC signal, said filter comprising:
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a common terminal, an input terminal and an output terminal; an inductor having first and second terminals, said first terminal of said inductor being connected to said input terminal of said filter, said second terminal being coupled to said output terminal of said filter; voltage sensing means for producing a sense signal which is proportional to an output voltage at said output terminal, said voltage sensing means being connected between said output terminal and said common terminal of said filter; an active filtering circuit having an input for receiving said sense signal and an output terminal, said active filtering circuit being adapted to generate at said output terminal of said active filtering circuit a correction signal having a magnitude and waveform such that coupling said correction signal onto said output terminal of said filter tends to reduce said ripple and noise voltages; a passive coupling element connected between said output terminal of said active filtering circuit and said output terminal of said filter; and a passive filter element connected between said output terminal and said common terminal of said filter, said passive coupling element and said passive filter element having nearly identical electrical characteristics. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification