Tunable biquad filter circuit including phase shift detection and methods for using such

摘要

Various embodiments of the present invention provide tunable filter circuits and methods for using such. As an example, a tunable biquad filter is disclosed that includes a tunable biquad circuit, a mixer circuit and a low pass filter. The tunable biquad circuit exhibits a cutoff frequency corresponding to an adjustment value, and is operable to receive an filter input and to provide a filter output. The mixer circuit is operable to provide a product of the filter input and the filter output. The product includes a time dependent component and a static component. The low pass filter is operable to receive the product and to provide the static component.

主权项

1. A filter circuit, the filter circuit comprising:
a tunable biquad circuit exhibiting a cutoff frequency corresponding to an adjustment value, wherein the tunable biquad circuit is operable to receive a filter input and to provide a filter output; a mixer circuit, wherein the mixer circuit is operable to provide a product of the filter input and the filter output, and wherein the product includes a time dependent component and a static component; a low pass filter, wherein the low pass filter is operable to receive the product and to provide the static component; and a transconductance circuit operable to receive a reference input and to provide a corresponding amplified output, wherein a gain of the amplified output is governed by a gain value.