Active EMI filter and power management device

Abstract

The embodiment of the invention discloses an active EMI filter and a power management device. The active EMI filter comprises an auxiliary source circuit, a current sampling circuit, a voltage-current conversion circuit, a biasing circuit and a current injection circuit. The auxiliary source circuit is used for conducting voltage stabilizing on voltage signals obtained from a power line and outputting the voltage signals which receive voltage stabilizing processing to other circuits for power supply, and common-mode noise currents sequentially pass through the current sampling circuit, the voltage-current conversion circuit and the current injection circuit and are finally injected to a protected area. The biasing circuit can compensate for input signals of the voltage-current conversion circuit according to current signals output by the voltage-current conversion circuit and provide a correct static working point for the voltage-current conversion circuit. According to the active EMI filter and the power management device, distortion of the active EMI filter can be prevented, and the performance and reliability of the active EMI filter are improved.

Description

technical field [0001] The invention relates to the field of electronic technology, in particular to an active EMI filter and a power management device. Background technique [0002] With the extensive application of electrical and electronic equipment, the problem of Electromagnetic Interference (EMI) is becoming more and more serious. In order to filter out the EMI signal on the wire, an active EMI filter is generally added to the circuit system. [0003] Commonly used active EMI filters usually use the voltage-current conversion circuit to process the voltage-current (V-I) conversion of the noise signal, and then inject the processed noise signal into the protection ground through the current injection circuit to avoid electromagnetic interference to other equipment , to achieve EMI filtering effect. Usually, the input differential circuit of the voltage-current conversion circuit cannot be completely symmetrical, and there is an offset voltage. However, in a general a...

AI Technical Summary

Problems solved by technology

Usually the input differential circuit of the voltage-current conversion circuit cannot be completely symmetrical, and there is an offset voltage

However, in a general active EMI filter, the current injection circuit is a DC blocking circuit. When the AC input is zero, the output signal of the voltage-current conversion circuit will have nothing to do with the current injection circuit, but is determined by the offset voltage. At this time, the voltage- The static operating point of the current conversion circuit will shift, resulting in distortion of the amplification circuit

In addition, the composition of the noise signal is very complex and may contain a small amount of transient DC components. If these DC components are not processed, the signal output by the amplifier circuit will be distorted.

The distortion of the amplifier circuit will greatly reduce the performance of the active EMI filter, and even cause the active EMI filter to fail to work properly.

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