Active low-pass filter based on positive feedback inductance substitution method

Abstract

The invention relates to an active low-pass filter based on a positive feedback inductance substitution method, belonging to the field of analog filter design. The active low-pass filter comprises capacitor units, an input unit and an active inductance unit, wherein the capacitor cell is used to integrate the low-pass filtering performance; the second capacitor and the fourth capacitance are used to transform active inductance; the input unit is used to convert an input signal in a voltage domain; the active inductance unit is used to realize the active inductance based on positive feedback. According to the invention, a high-order active low-pass filter is designed by the inductance substitution method on the basis of the positive feedback technology, so that the filter can be influenced by process variation hardly; since analog signals are processed by using a current multiplexing technology and the voltage domain, high linearity can be obtained with low power consumption; few transistors are used, the structure is symmetrical and simple and is easy to design; and meanwhile, different pass band grains can be realized through adjusting the width ratio of a first PMOS (P-channel metal oxide semiconductor) tube to a third PMOS tube and a second PMOS tube to a fourth PMOS tube in an input part.

Description

technical field [0001] The invention relates to the field of analog filter design, in particular to an active low-pass filter based on a positive feedback inductance substitution method. Background technique [0002] With the rapid development of analog filter design technology based on CMOS technology, new filter circuit structures are constantly emerging. D'Amico in reference "Stefano D'Amico, Matteo Conta and Andrea Baschirotto, "A4.1-mW 10-MHz Fourth-Order Source-Follower-Based Continuous-Time Filter With 79-dB DR," IEEE Journal of Solid- State Circuits, pp.2713-2719, Dec.2006 describes that the source follower-based active filter breaks the traditional active filter design structure and achieves high linearity and high dynamic range at low power consumption . figure 1 A first-order source-follower-based integrator is shown in p1 (its transconductance is G m1 ) and load capacitance C L Form an integrator whose transfer function is: [0003] H ...

AI Technical Summary

Problems solved by technology

[0007] In short, there are two shortcomings in the current existing technology: (1) The high-order filter realized by cascading method based on biquad cells is greatly affected by process deviation; (2) The circuit design of the inductance substitution method based on negative feedback technology is complicated , using more transistors

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