US5248943A — Multi-view coil bandpass filter array system

Claim 1

Independent Claim 172 words

An MRI signal processing apparatus for providing a low noise output signal including a plurality of input channels for receiving a plurality of MRI signals, each MRI signal originating from a sensing coil which produces an MRI signal in a first frequency range, comprising: input mixer means for frequency shifting each of the plurality of MRI signal from the first frequency range to a second frequency range; controllable bandpass filter means coupled to the input mixer means for bandpass filtering each of the plurality of frequency shifted MRI signals; output mixer means for frequency shifting each MRI signal output from the controllable bandpass filter means from the second frequency range to the first frequency range; summing means for combining the frequency shifted signals output from the output mixer means to produce the low noise output signal; mixer control means for controlling the respective frequency shifts of the input mixer means and the output mixer means; and filter control means for controlling bandwidth and phase shift characteristics of the controllable bandpass filter means.

Claim 2

Dependent Claim 172 words

An MRI signal processing apparatus for providing a low noise output signal including a plurality of input channels for receiving a plurality of MRI signals, each MRI signal originating from a sensing coil which produces an MRI signal in a first frequency range, comprising: input mixer means for frequency shifting each of the plurality of MRI signal from the first frequency range to a second frequency range; controllable bandpass filter means coupled to the input mixer means for bandpass filtering each of the plurality of frequency shifted MRI signals; output mixer means for frequency shifting each MRI signal output from the controllable bandpass filter means from the second frequency range to the first frequency range; summing means for combining the frequency shifted signals output from the output mixer means to produce the low noise output signal; mixer control means for controlling the respective frequency shifts of the input mixer means and the output mixer means; and filter control means for controlling bandwidth and phase shift characteristics of the controllable bandpass filter means.

Claim 3

Dependent Claim 18 words

The apparatus of claim 1, wherein the input mixer means comprises bandpass filter means for removing unwanted frequencies.

Claim 4

Dependent Claim 19 words

The apparatus of claim 1, wherein the output mixer means comprises a bandpass filter means for removing unwanted frequencies.

Claim 5

Dependent Claim 45 words

The apparatus of claim 1, wherein the input mixer means further comprises: band pass filter means for passing a wide range of frequencies; and signal mixer means for mixing a signal from the first buffer amplifier means with a signal from the mixer control means.

Claim 6

Dependent Claim 37 words

The apparatus of claim 4, wherein the input mixer means further comprises: first buffer amplifier means coupled to the band pass filter means; and second buffer amplifier means coupled to the output of the signal mixer means.

Claim 7

Dependent Claim 50 words

The apparatus of claim 1, wherein the input mixer means comprises a plurality of signal mixer means for respectively mixing the MRI signals of the plurality of input channels with a signal from the mixer control means to produce a plurality of MRI output signals in the second frequency range.

Claim 8

Dependent Claim 46 words

The apparatus of claim 6, wherein each MRI signal is in a desired adjacent sub frequency range within the first frequency range and wherein each MRI signal is frequency shifted by a corresponding one of the plurality of signal mixer means to the second frequency range.

Claim 9

Dependent Claim 29 words

The apparatus of claim 1, wherein the controllable bandpass filter means comprises a plurality of bandpass filters for respectively receiving the MRI signals of the plurality of input channels.

Claim 10

Dependent Claim 17 words

The apparatus of claim 8, wherein each bandpass filter has the second frequency range as a passband.

Claim 11

Dependent Claim 32 words

The apparatus of claim 1, wherein the controllable bandpass filter means comprises a plurality of quadrature bandpass filters for respectively receiving the frequency shifted MRI signals received from the input mixer means.

Claim 12

Dependent Claim 75 words

The apparatus of claim 10, wherein each quadrature bandpass filter comprises: a pair of input signal mixers for down mixing the MRI signal to a baseband frequency range; a pair of controllable lowpass filters coupled to the pair of input signal mixers; and a pair of output signal mixers for up mixing a signal from a baseband frequency range to the frequency range of the frequency shifted MRI signals received from the input mixer means.

Claim 13

Dependent Claim 35 words

The apparatus of claim 11, wherein each quadrature bandpass filter further comprises a bandpass filter, coupled to the pair of output signal mixers, for removing unwanted frequencies from the output of the output signal mixers.

Claim 14

Dependent Claim 63 words

The apparatus of claim 11, wherein the pair of input signal mixers receives a first and a second mixing signal and the pair of output signal mixers receives a third and a fourth mixing signal, the first and second mixing signals having a desired first phase difference therebetween and the third and fourth mixing signals having the same desired first phase difference therebetween.

Claim 15

Dependent Claim 14 words

The apparatus of claim 13, wherein the desired first phase difference is 90 degrees.

Claim 16

Dependent Claim 51 words

The apparatus of claim 13, wherein the first and third mixing signals have a desired second phase difference therebetween and the second and fourth mixing signals having the same desired second phase difference therebetween, the second phase difference being selected to control an overall phase shift of each quadrature bandpass filter.

Claim 17

Dependent Claim 14 words

The apparatus of claim 15, wherein the desired second phase difference is 90 degrees.

Claim 18

Dependent Claim 34 words

The apparatus of claim 11, wherein each of the controllable lowpass filters includes a switched capacitor lowpass filter which is controlled by a signal with a variable clock frequency from the filter control means.

Claim 19

Dependent Claim 20 words

The apparatus of claim 11, wherein each of the controllable lowpass filters comprises: an anti-aliasing filter; and a lowpass filter.

Claim 20

Dependent Claim 22 words

The apparatus of claim 11, wherein each of the controllable lowpass filters comprises: a lowpass filter; and an active high pass filter.

Claim 21

Dependent Claim 52 words

The apparatus of claim 1, wherein the output mixer means comprises a plurality of signal mixer means for mixing the plurality of bandpass filtered signals from the controllable bandpass filter means with a signal from the mixer control means to produce a plurality of MRI output signals in the first frequency range.

Claim 22

Dependent Claim 36 words

The apparatus of claim 1, wherein the input mixer means and the output mixer means receive identical signals from the mixer control means to provide exactly opposite frequency shift upon input mixing and output mixing, respectively.

Claim 23

Dependent Claim 26 words

The apparatus of claim 1, wherein the summing means includes a summing amplifier which adds a plurality of MRI output signals from the output mixing means.

Claim 24

Dependent Claim 68 words

The apparatus of claim 1, wherein the filter control means comprises: local oscillator means for generating a single frequency signal; phase network means coupled to the controllable bandpass filter means for producing a plurality of phase shifted output signals from the single frequency signal generated by the local oscillator means; and filter oscillator means for generating a signal to control a bandwidth of the controllable bandpass filter means.

Claim 25

Dependent Claim 46 words

The apparatus of claim 23, wherein the phase network means produces four signals at the same frequency from the single frequency signal from the local oscillator means, and wherein the four signals have phase angles of 0°, 90°, 180°, and 270° with respect to each other.

Claim 26

Dependent Claim 32 words

The apparatus of claim 1, wherein the mixer control means comprises a controllable multiple frequency oscillator which provides a plurality of output frequencies to the input mixer means and output mixer means.

Claim 27

Dependent Claim 25 words

The apparatus of claim 25, wherein the plurality of frequencies output from the controllable multiple frequency oscillator are regularly spaced in a desired frequency range.

Claim 28

Dependent Claim 211 words

An MRI signal processing apparatus for providing a low noise output signal including a plurality of input channels for receiving a plurality of MRI signals, each MRI signal originating from a sensing coil, comprising: quadrature bandpass filter means for bandpass filtering each MRI signal to remove unwanted noise from the MRI signal, the quadrature bandpass filter means including a plurality of quadrature bandpass filters, each filter including: a pair of input signal mixers for down mixing the MRI signal to a baseband frequency range; a pair of controllable lowpass filters coupled to the pair of input signal mixers; a pair of output signal mixers for up mixing a signal from a baseband frequency range to a frequency range of the MRI signal inputted to the pair of input signal mixers; summing means for combining the filtered MRI signals outputted by the quadrature bandpass filter means to produce the low noise output signal; and filter control means for controlling bandwidth and phase shift characteristics of the quadrature bandpass filter means, the filter control means including local oscillator means for generating a single frequency signal and phase network means for producing a plurality of phase shifted output signals from the single frequency signal to control the phase shift of the quadrature bandpass filters.

Claim 29

Dependent Claim 211 words

An MRI signal processing apparatus for providing a low noise output signal including a plurality of input channels for receiving a plurality of MRI signals, each MRI signal originating from a sensing coil, comprising: quadrature bandpass filter means for bandpass filtering each MRI signal to remove unwanted noise from the MRI signal, the quadrature bandpass filter means including a plurality of quadrature bandpass filters, each filter including: a pair of input signal mixers for down mixing the MRI signal to a baseband frequency range; a pair of controllable lowpass filters coupled to the pair of input signal mixers; a pair of output signal mixers for up mixing a signal from a baseband frequency range to a frequency range of the MRI signal inputted to the pair of input signal mixers; summing means for combining the filtered MRI signals outputted by the quadrature bandpass filter means to produce the low noise output signal; and filter control means for controlling bandwidth and phase shift characteristics of the quadrature bandpass filter means, the filter control means including local oscillator means for generating a single frequency signal and phase network means for producing a plurality of phase shifted output signals from the single frequency signal to control the phase shift of the quadrature bandpass filters.

Claim 30

Independent Claim 121 words

A method for processing a plurality of MRI signals to provide a low noise output signal including a plurality of input channels for receiving the plurality of MRI signals, each MRI signal originating from a sensing coil which produces the MRI signal in a first frequency range, comprising the steps of: frequency shifting each of the plurality of MRI signals from the first frequency range to a second frequency range; bandpass filtering each frequency shifted MRI signal to remove unwanted noise from the MRI signal; frequency shifting each bandpass filtered MRI signal from the second frequency range to the first frequency range; and combining the MRI signals frequency shifted to the first frequency range to produce the low noise output signal.

Claim 31

Independent Claim 121 words

A method for processing a plurality of MRI signals to provide a low noise output signal including a plurality of input channels for receiving the plurality of MRI signals, each MRI signal originating from a sensing coil which produces the MRI signal in a first frequency range, comprising the steps of: frequency shifting each of the plurality of MRI signals from the first frequency range to a second frequency range; bandpass filtering each frequency shifted MRI signal to remove unwanted noise from the MRI signal; frequency shifting each bandpass filtered MRI signal from the second frequency range to the first frequency range; and combining the MRI signals frequency shifted to the first frequency range to produce the low noise output signal.

Claim 32

Independent Claim 126 words

A method for processing a plurality of MRI signals to provide a low noise output signal including a plurality of input channels, each input channel originating from a sensing coil which produces an MRI signal, comprising the steps of: bandpass filtering each of the plurality of MRI signal to remove unwanted noise from the MRI signal, the bandpass filtering step including the substeps of: down mixing each MRI signal to a baseband frequency range to produce first and second signals in phase quadrature; lowpass filtering the first and second signals to remove unwanted noise therefrom; and up mixing and recombining the lowpass filtered first and second signals to produce a filtered signal; and combining the plurality of filtered signals to produce the low noise output signal.

Claim 33

Independent Claim 126 words

A method for processing a plurality of MRI signals to provide a low noise output signal including a plurality of input channels, each input channel originating from a sensing coil which produces an MRI signal, comprising the steps of: bandpass filtering each of the plurality of MRI signal to remove unwanted noise from the MRI signal, the bandpass filtering step including the substeps of: down mixing each MRI signal to a baseband frequency range to produce first and second signals in phase quadrature; lowpass filtering the first and second signals to remove unwanted noise therefrom; and up mixing and recombining the lowpass filtered first and second signals to produce a filtered signal; and combining the plurality of filtered signals to produce the low noise output signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-09-27	1997-03-29	1997-09-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-09-27	2001-03-29	2001-09-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-09-27	2005-03-29	2005-09-28	$7700.00	Window Closed / Lapsed

Multi-view coil bandpass filter array system

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