On-chip low pass filter

Abstract

The invention discloses an on-chip low pass filter consisting of four P-channel MOS (Metal Oxide Semiconductor) transistors, two capacitors and a current source. On the basis of the traditional on-chip low pass filter, an outside control circuit for starting a circuit is removed, and an MOS transistor and a capacitor are additionally provided to form another low pass filtering unit for carrying out low pass filtering on high input noise of the whole circuit so as to prevent the high input noise from being fed forward to output by a parasitic capacitor of the MOS transistor and improve a filtering performance of the on-chip low pass filter. The low pass filtering unit further forms a fast start-up circuit with the current source, thus a complex control circuit in the prior art is saved, the cost can be effectively saved, and the design area can be reduced.

Description

technical field [0001] The invention relates to the technical field of low-pass filter design, in particular to an on-chip low-pass filter. Background technique [0002] The on-chip low-pass filter is an important part of the low-noise linear regulator, and the filtering performance of the on-chip low-pass filter is directly related to the working performance of the low-noise linear regulator. In the design of low-noise linear regulators, the design of the on-chip low-pass filter requires a very low cut-off frequency, generally around 1Hz. In addition, due to the consideration of the design area, the simplicity of the circuit is also one of the important issues to be considered in the design. [0003] Such as figure 1 Shown is a circuit schematic diagram of an on-chip low-pass filter in the prior art. The MOS transistor M1 is the resistive element of the filter, the capacitor C1 is the capacitive element of the filter, the MOS transistor M2 provides a bias voltage for the...

AI Technical Summary

Problems solved by technology

[0006] In view of this, the present invention provides an on-chip low-pass filter to solve the problems of existing on-chip low-pass filter with poor ability to filter out high-frequency signals and complex structure. The technical solution is as follows:

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