| 摘要 |
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.
|
