Feed-forward filtering device and associated method

Patent metadata

Field	Value
Publication number	US-10756933-B2
Application number	US-201715853878-A
Country	US
Kind code	B2
Filing date	Dec 25, 2017
Priority date	Mar 1, 2016
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A filtering device includes a low-pass filter (LPF), a noise estimation circuit and a first combining circuit. The LPF receives and filters a pre-filtering signal to generate an output signal of the filtering device. The noise estimation circuit estimates an estimated noise signal according to the output signal and the pre-filtering signal. The first combining circuit subtracts the estimated noise signal from an input signal of the filtering device to generate the pre-filtering signal.

First claim

What is claimed is:

1. A filtering device, comprising:
a low-pass filter (LPF), arranged to receive and filter a pre-filtering signal from an interconnection node to generate an output signal of the filtering device;
a feedback circuit, arranged to receive the output signal to generate a feedback signal; and
a resistor circuit, wherein the resistor circuit comprises a voltage divider coupled between an input signal of the filtering device and the feedback signal, and the voltage divider generates the pre-filtering signal at the interconnection node using the input signal and the feedback signal;
wherein the input signal, the pre-filtering signal and the output signal are voltage signals,
wherein the voltage divider comprises:
a first resistor, wherein a first terminal of the first resistor is directly connected to the interconnection node and a second terminal of the first resistor is coupled to the input signal; and
a second resistor, wherein a first terminal of the second resistor is coupled to the interconnection node and a second terminal of the second resistor is directly connected to the feedback signal, and

wherein the feedback circuit comprises a feedback buffer that generates the feedback signal based on the output signal.

2. The filtering device of claim 1 , further comprising: a buffer, coupled between the input signal and the first resistor.

3. The filtering device of claim 1 , wherein the low-pass filter is a resistor-capacitor filter.

4. The filtering device of claim 3 , wherein the low-pass filter comprises:
a resistor, coupled between the output signal and the interconnection node; and
a capacitor, coupled between the output signal and a reference voltage.

5. The filtering device of claim 1 , wherein the interconnection node is connected to the LPF, and the LPF directly receives the pre-filtering signal from the interconnection node.

6. The filtering device of claim 1 , wherein the feedback circuit buffers the output signal to generate a buffered output signal serving as the feedback signal.

7. A filtering method, comprising:
performing a low-pass filtering (LPF) operation upon a pre-filtering signal received from an interconnection node to generate an output signal;
generating a feedback signal by a feedback buffer based on the output signal; and
using a resistor circuit comprising a voltage divider coupled between an input signal and the feedback signal to divide the input signal with the feedback signal to generate the pre-filtering signal at the interconnection node, wherein the voltage divider generates the pre-filtering signal at the interconnection node, wherein the voltage divider comprises a first resistor, wherein a first terminal of the first resistor is directly connected to the interconnection node and a second terminal of the first resistor is coupled to the input signal, and the resistor circuit comprises a second resistor, wherein a first terminal of the second resistor is coupled to the interconnection node and a second terminal of the second resistor is directly connected to the feedback signal,
wherein the input signal, the pre-filtering signal and the output signal are voltage signals.

8. The filtering method of claim 7 , further comprising:
buffering the input signal to generate a buffered input signal to the first resistor.

9. The filtering method of claim 7 , wherein performing the LPF operation upon the pre-filtering signal from the interconnection node to generate the output signal comprises:
using a resistor-capacitor filter to filter the pre-filtering signal from the interconnection node to generate the output signal.

10. The filtering method of claim 9 , wherein the resistor-capacitor filter comprises:
a resistor, coupled between the output signal and the interconnection node; and
a capacitor, coupled between the output signal and a reference voltage.

Assignees

• Mediatek Inc

Inventors

• Lu Tai-You

Classifications

• H03H11/1213

  using transistor amplifiers (H03H11/1204 takes precedence; parallel-T filters H03H11/1295) · CPC title

• H03H11/1269

  Filters using the operational amplifier pole · CPC title

• H03H11/0461

  Current mode filters · CPC title

• H04L25/03993 Primary

  Noise whitening · CPC title

• G10K2210/108

  Communication systems, e.g. where useful sound is kept and noise is cancelled · CPC title