US 2018/0295758 A1 · COMPENSATED ACTIVE ELECTRO-MAGNETIC INTERFERENCE FILTERS

Abstract

An active electromagnetic interference (EMI) filter includes an amplifier configured to sense noise signals on a power conductor, and drive a cancellation signal onto the power conductor. The cancellation signal is to reduce the amplitude of the noise signals. Some embodiments of the active EMI filter include a high frequency compensation network that improves the high frequency phase margin of the active EMI filter and improves the stability of the active EMI filter at high frequencies. Some embodiments of the active EMI filter include a low frequency compensation capacitor that increases the phase margin of the active EMI filter at low frequencies. Some embodiments of the active EMI filter include low frequency compensation circuitry that increases the low frequency tolerance of the active EMI filter.

Claims20

Dependent claims

An active electromagnetic interference (EMI) filter, comprising:

an amplifier configured to:
sense noise signals on a power conductor;
and
drive a cancellation signal, to reduce an amplitude of the noise signals, onto the power conductor;
a high frequency compensation network connected to the power conductor and a reference conductor, the high frequency compensation network comprising:
a first capacitor;
and
a first resistor;
wherein the first capacitor and the first resistor are connected in series across the power conductor and the reference conductor.

6 more elements

An active electromagnetic interference (EMI) filter, comprising:

an amplifier configured to:
sense noise signals on a power conductor;
and
drive a cancellation signal, to reduce an amplitude of the noise signals, onto the power conductor;
a first sense capacitor in series with a second sense capacitor;
wherein:
a first terminal of the first sense capacitor is connected to the power conductor;
a first terminal of the second sense capacitor is connected to an inverting input of the amplifier;
and
a second terminal of the first sense capacitor is connected to a second terminal of the second sense capacitor;
a first injection capacitor in series with a second injection capacitor;
wherein:
a first terminal of the first injection capacitor is connected to the power conductor;
a first terminal of the second injection capacitor is connected to an output of the amplifier;
and
a second terminal of the first injection capacitor is connected to a second terminal of the second injection capacitor;
a compensation capacitor connected between a sensing capacitor branch and an injection capacitor branch, wherein:
a first terminal of the compensation capacitor is connected to the second terminal of the first sense capacitor;
and
a second terminal of the compensation capacitor is connected to the second terminal of the first injection capacitor.

17 more elements

An active electromagnetic interference (EMI) filter, comprising:

an amplifier configured to:
sense noise signals on a power conductor;
and
drive a cancellation signal, to reduce an amplitude of the noise signals, onto the power conductor;
a first resistor connected to provide feedback from an output of the amplifier to an inverting input of the amplifier;
and
a first low frequency compensation capacitor connected to provide feedback from the output of the amplifier to the inverting input of the amplifier.

4 more elements

Dependencies are inferred from the claim text.

Compensated active electro-magnetic interference filters

Life of this patent

Compensated active electro-magnetic interference filters

Life of this patent

Abstract

Claims20