US 12,009,796 B2 · High-order passive filter with capacitive inner tapping technique

Abstract

A high-order filter with a capacitive inner tapping technique is disclosed. The filter includes an inductor and a first resonant circuit including a first portion of the inductor and a first capacitor. The first resonant circuit is configured to attenuate first frequency components of an input signal above a cutoff frequency to generate a filtered signal. The filter further includes a second resonant circuit coupled in parallel with the first resonant circuit and including the first portion of the inductor and a second capacitor. The second resonant circuit is configured to attenuate the first frequency components of the input signal to generate the filtered signal. A third resonant circuit includes a second portion of the inductor and a third capacitor, wherein the third resonant circuit is configured to attenuate second frequency components of the filtered signal above the cutoff frequency to generate an output signal.

Claims20

Dependent claims

An apparatus comprising:

a filter circuit configured to attenuate frequency components in a differential input signal outside of a filter passband to generate a filtered differential signal, wherein the filter circuit includes;
a first inductor coupled between a first input port and a first output port of the filter circuit;
a second inductor coupled between a second input port and a second output port of the filter circuit, wherein the first and second inductors share a magnetic core;
a first capacitance coupled between the first input port and a first tap point of the first inductor such that the first capacitance is in parallel with a first portion of the first inductor and in series with a second portion of the first inductor;
and
a second capacitance coupled between the second input port and a second tap point of the second inductor such that the second capacitance is in parallel with a first portion of the second inductor and in series with a second portion of the second inductor.

3 more elements

A method comprising:

attenuating, using a filter circuit, frequency components outside of a filter passband present in a differential input signal, wherein the attenuating includes:
inputting a first component of the differential input signal, via a first input port, into a first inductor coupled between the first input port and a first output port;
inputting a second component of the differential input signal, via a second input port, into a second inductor coupled between the second input port and a second output port;
attenuating at least a portion of the frequency components from the first component of the differential input signal using a first resonant circuit including a first capacitance coupled between the first input port and a first tap point of the first inductor such that the first capacitance is in parallel with a first portion of the first inductor and in series with a second portion of the first inductor;
attenuating at least a portion of the frequency components from the second component of the differential input signal using a second capacitance coupled between the second input port and a second tap point of the second inductor such that the second capacitance is in parallel with a first portion of the second inductor and in series with a second portion of the second inductor;
and
outputting first and second components of a filtered differential signal from the first and second output ports, respectively.

4 more elements

A system comprising:

a digital-to-analog converter (DAC) configured to output an analog signal based on a digital word;
a filter circuit configured to generate a filtered signal based on the analog signal, wherein the filter circuit includes:
a first inductor coupled between a first input port and a first output port of the filter circuit;
and
a first capacitance coupled between the first input port and a first tap point of the first inductor such that the first capacitance is in parallel with a first portion of the first inductor and in series with a second portion of the first inductor, wherein the filter circuit is further configured to output at least a portion of the filtered signal on the first output port;
and
a transmitter circuit configured to generate and transmit a radio frequency signal based on the filtered signal.

4 more elements

Dependencies are inferred from the claim text.

High-order passive filter with capacitive inner tapping technique

Life of this patent

High-order passive filter with capacitive inner tapping technique

Life of this patent

Abstract

Claims20