US 9,287,851 B2Granted

Finite impulse response filter for producing outputs having different phases

AssigneeESS Technology, Inc.

InventorsA. Martin Mallinson, Hu Jing Yao, Dustin Forman

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Abstract

A method and system for designing and implementing a finite impulse response (FIR) filter to create a plurality of output signals, each output signal having the same frequency but at a different phase shift from the other output(s), is described. Values are determined for the resistors, or other elements having impedance values, in a FIR filter having a plurality of outputs, such that each output has the same frequency response but a different phase than the other output(s). This is accomplished by the inclusion of a phase factor in the time domain calculation of the resistor values that does not change the response in the frequency domain. The phase shift is constant and independent of the frequency of the output signal.

Claims19

Dependent claims

A method of designing a finite impulse response filter having a delay line containing a plurality of delay elements, comprising:

receiving at a processor a selected frequency response for the filter;
calculating by the processor an impedance value for each of a first plurality of impedance elements of a single type by approximating a first set of Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a first phase factor and selecting a set of impedance values that are an inverse of the first set of Fourier transform coefficients, each impedance element from the first plurality of impedance elements to be coupled to the delay line after a different delay element than each other impedance element in the first plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the first plurality of impedance elements calculated such that a sum of the outputs of the first plurality of impedance elements is a first output signal of the selected frequency response;
calculating by the processor an impedance value for each of a second plurality of impedance elements of a single type by approximating a second set of Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a second phase factor and selecting a set of impedance values that are an inverse of the second set of Fourier transform coefficients, each impedance element from the second plurality of impedance elements to be coupled to the delay line after a different delay element than each other impedance element in the second plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the second set of impedance elements calculated such that a sum of the outputs of the second plurality of impedance elements is a second output signal of the selected frequency response, but having a different phase from the first output signal;
and connecting the outputs of the first plurality of impedance elements to provide the first output signal, and connecting the outputs of the second plurality of impedance elements to provide the second output signal.

1 more element

A finite impulse response filter comprising:

an input configured to receive an input signal;
a delay line comprising a plurality of delay elements in series and connected to the input for propagating and delaying the input signal;
a first plurality of buffers, each buffer in the first plurality of buffers receiving the delayed input signal after the input signal has passed through a separate one of the plurality of delay elements;
a first plurality of impedance elements of a single type having impedance values, each of the first plurality of impedance elements connected to a different one of the first plurality of buffers than each other impedance element in the first plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the first plurality of impedance elements being the inverse of a first set of approximated Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a first phase factor, such that the sum of the outputs of the first plurality of impedance elements produces a selected frequency response to the input signal;
a first output connected to the first plurality of impedance elements to produce a first output signal having the selected frequency response;
a second plurality of buffers, each buffer in the second plurality of buffers receiving the delayed input signal after the input signal has passed through a separate one of the plurality of delay elements;
a second plurality of impedance elements of a single type having impedance values, each of the second plurality of impedance elements connected to a different one of the second plurality of buffers than each other impedance element in the second plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the second plurality of impedance elements being the inverse of a second set of approximated Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a second phase factor, such that the sum of the outputs of the second plurality of impedance elements produces the selected frequency response to the input signal as the first plurality of impedance elements but at a different phase;
and a second output connected to the second plurality of impedance elements to produce a second output signal having the selected frequency response, at the different phase from the first output signal.

5 more elements

A finite impulse response filter comprising:

an input configured to receive an input signal;
a delay line comprising a plurality of delay elements in series and connected to the input for propagating and delaying the input signal;
a plurality of buffers, each buffer receiving the delayed input signal after the input signal has passed through a separate one of the plurality of delay elements;
a first plurality of impedance elements of a single type having impedance values, each of the first plurality of elements connected to a different one of the plurality of buffers than each other impedance element in the first plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the first plurality of impedance elements being the inverse of a first set of approximated Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a first phase factor, such that the sum of the outputs of the first plurality of impedance elements produces a selected frequency response to the input signal;
a first output connected to the first plurality of impedance elements to produce a first output signal having the desired frequency response;
a second plurality of impedance elements of a single type having impedance values, each of the second plurality of elements connected to a different one of the plurality of buffers than each other impedance element in the first plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the second plurality of impedance elements being the inverse of a second set of approximated Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a second phase factor, such that the sum of the outputs of the second plurality of impedance elements produces the same frequency response to the input signal as the first plurality of elements but at a different phase;
and a second output connected to the second plurality of impedance elements to produce a second output signal having the selected frequency response, at a different phase from the first output signal.

4 more elements

A non-transitory computer readable storage medium having embodied thereon instructions for causing a computing device to execute a method for designing a finite impulse response filter having a delay line containing a plurality of delay elements, the method comprising:

receiving a selected frequency response for the filter;
calculating an impedance value for each of a first plurality of impedance elements of a single type by approximating a first set of Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a first phase factor and selecting a set of impedance values that are an inverse of the first set of Fourier transform coefficients, each impedance element from the first plurality of impedance elements to be coupled to the delay line after a different delay element than each other impedance element in the first plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the first plurality of impedance elements calculated such that a sum of the outputs of the first plurality of impedance elements is a first output signal of the selected frequency response;
calculating an impedance value for each of a second plurality of impedance elements of a single type by approximating a second set of Fourier transform coefficients of a Dirac function corresponding to the selected frequency response with a second phase factor and selecting a set of impedance values that are an inverse of the second set of Fourier transform coefficients, each impedance element from the second plurality of impedance elements to be coupled to the delay line after a different delay element than each other impedance element in the second plurality of impedance elements so as to receive a delayed input signal and provide an output weighted by the impedance value of the impedance element, the impedance values of the second set of impedance elements calculated such that a sum of the outputs of the second plurality of impedance elements is a second output signal of the selected frequency response, but having a different phase from the first output signal;
and providing a connection of the outputs of the first plurality of impedance elements to provide the first output signal, and a connection of the outputs of the second plurality of impedance elements to provide the second output signal.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 13/414,487Filed 7 Mar 2012 · us provisional application
Priority: 22 Mar 2011
Published: US 2012/0245901 A127 Sep 2012
Granted: 15 Mar 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H03H 15/02
Transversal filters: using analogue shift registers
G06F 30/20
Computer-aided design [CAD]: design optimisation, verification or simulation
H03K 5/15
Manipulating of pulses not covered by one of the other main groups of this subclass: arrangements in which pulses are delivered at different times…
H03K 5/1536
Arrangements in which a pulse is delivered at the instant when a predetermined characteristic of an input signal is present or at a fixed time…:…