Abstract: A high-frequency amplifier for an active EMI filter with a symmetric class B emitter-follower output stage driven by a driver stage, with a sense output resistor. Both terminals of the sense resistor are brought to the noninverting, respecting inverting input of the driver stage through two dividers of the same ratio, in a global voltage feedback loop. The amplifier is configured to provide a high output impedance at 10 kHz and up to 100 MHz, a peak-to-peak output current of 2-10 ampere and a low quiescent current of less than 400 mA. The invention includes EMI filters with such a high-frequency current source, for example in the current-sense current-inject feedback configuration.

Abstract: A safety device for an automotive EMI filter that is connected in series with a filtering capacitor. The safety device has normally a low impedance and does not alter the functioning of the filter, but it is configured to present an increased inductance in the event of a discharge. The device reduces the discharge current that can be accidentally conducted through a human body.

Abstract: A high-frequency amplifier for an active EMI filter with a symmetric class B emitter-follower output stage driven by a driver stage, with a sense output resistor. Both terminals of the sense resistor are brought to the noninverting, respecting inverting input of the driver stage through two dividers of the same ratio, in a global voltage feedback loop. The amplifier is configured to provide a high output impedance at 10 kHz and up to 100 MHz, a peak-to-peak output current of 2-10 ampere and a low quiescent current of less than 400 mA. The invention includes EMI filters with such a high-frequency current source, for example in the current-sense current-inject feedback configuration.

Abstract: A high-frequency current source with a symmetric bipolar output stage piloted by an active bias network with an extended temperature range. The source is configured to provide a high impedance at 1 MHz and above. The invention includes such active EMI filters with such a high-frequency current source, for example in the current-sense current-inject feedback configuration.

Abstract: An active filter for suppressing an unwanted noise component from an electric supply line connecting a noise source and a load device, the active filter comprising a first active stage and a second active stage on the supply line, wherein the first active stage is between the noise source and the second active stage, wherein the first active stage has a first attenuation, and the second active stage has a second attenuation, characterized in that the first attenuation is lower than the second attenuation.

Abstract: Electromagnetic interference filter for suppressing interferences in DC network, the network comprising a source device powering a load device via a bus connectable to the source device at an input side and to the load device at an output side. The EMI filter being connected to the bus and comprising an active filter circuit having an active filter bandwidth and being configured to sense a noise component superimposed in the bus and inject a cancelling noise in the bus to suppress said noise component. The EMI filter further comprises a passive circuit including a source circuit connected to the bus at the input side and a passive load circuit to the bus connected at the output side, the passive circuit being configured to provide, at least at a cutoff frequency of the active filter bandwidth, a source impedance at the input side that differs from a load impedance at the output side by a factor of at least two.