Voltage following filtering circuit

Abstract

The invention provides a voltage following filtering circuit. The voltage following filtering circuit comprises an input sampling filtering circuit, an output sampling circuit, a following circuit, afiltering and feedback control circuit and a power loop, wherein the input sampling filtering circuit is connected with a voltage input end, the output sampling circuit is connected with a voltage output end, the voltage input end is connected with the voltage output end by the power loop, an output end of the input sampling filtering circuit and an output end of the output sampling circuit are connected with an input end of the following circuit, and an output end of the following circuit is connected with an input end of the filtering and feedback control circuit. The voltage following filtering circuit has the beneficial effects that the change of an input power supply can be followed, effective DC constituent of power supply is effectively maintained, the voltage following filtering circuit can be widely applied to power supply filtering loops having various voltages and particularly can be applied to a circuit of which an output voltage is needed to adjust, ripple and noise are only filtered, the DC constituent of the power supply is completely maintained, the power consumption of a filter is reduced, and energy saving and emission reduction are achieved.

Description

technical field [0001] The invention relates to a filter circuit, in particular to a power supply following filter circuit. Background technique [0002] Some DC power supply equipment is very sensitive to the ripple noise of the DC input Vin. Therefore, it is necessary to filter the power supply to filter out the AC components of the ripple noise to obtain the expected DC components. [0003] At present, the traditional solution is mainly to use the switching power supply or the linear power supply rectified by the transformer to supply power to the rear stage, and the following solutions are generally used: [0004] Scheme 1: Passive filter circuit: LC filter composed of capacitor C filter or inductor L+capacitor C, the principle is as follows, the input power Vin passes through L1 and C1 to obtain Vout1. [0005] Solution 2: Low dropout linear regulator LDO (low dropout regulator) active filter circuit uses a three-terminal regulator to obtain a fixed DC output. The prin...

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Problems solved by technology

[0009] Among the filtering methods of Scheme 1 and Scheme 2 above, Scheme 1 can only filter out ripple noise, but for low-frequency ripple noise, the cost is too high, or even invalid

Solution 2 is effective for ripple noise, but it will cut off the effective DC component of the power supply. It is especially not suitable for scenarios where Vin is not fixed, and it will cause a lot of loss

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