US5225836A — Electronic filters, repeated signal charge conver…

Claim 1

Independent Claim 175 words

Electronic signal conversion apparatus comprising: means for temporarily holding a digital value which is to be converted to analog form; first and second capacitors; switch means generally operable for executing selective operations including selectively charging at least one of the first and second capacitors, selectively discharging at least one of the first and second capacitors so that a redistribution of charge between them occurs; and means, responsive to said means for temporarily holding the digital value which is to be converted to analog form, for operating said switch means to make it perform a sequence of the selective operations among which operations the redistribution of charge repeatedly occurs a number of times, wherein the number is a function of the digital value which is to be converted to analog form, so that the voltage across at least one of said capacitors after the operations are executed is an analog voltage which is representative of the digital value which is to be converted to analog form; whereby a digital to analog electronic signal conversion is accomplished.

Claim 2

Dependent Claim 175 words

Electronic signal conversion apparatus comprising: means for temporarily holding a digital value which is to be converted to analog form; first and second capacitors; switch means generally operable for executing selective operations including selectively charging at least one of the first and second capacitors, selectively discharging at least one of the first and second capacitors so that a redistribution of charge between them occurs; and means, responsive to said means for temporarily holding the digital value which is to be converted to analog form, for operating said switch means to make it perform a sequence of the selective operations among which operations the redistribution of charge repeatedly occurs a number of times, wherein the number is a function of the digital value which is to be converted to analog form, so that the voltage across at least one of said capacitors after the operations are executed is an analog voltage which is representative of the digital value which is to be converted to analog form; whereby a digital to analog electronic signal conversion is accomplished.

Claim 3

Dependent Claim 68 words

Electronic signal conversion apparatus as set forth in claim 1 wherein the number of times that the redistribution of charge occurs is substantially proportional to the digital value which to be converted to analog form, so that the voltage across one of said capacitors after the operations are executed is an analog voltage which is representative of the digital value which is to be converted to analog form.

Claim 4

Dependent Claim 60 words

Electronic signal conversion apparatus as set forth in claim 1 wherein said means for operating said switch means includes means for causing said switch means to perform a sequence of initially charging the first capacitor, and repeatedly both discharging the second capacitor and then connecting the first and second capacitors so that charge is progressively removed from the first capacitor.

Claim 5

Dependent Claim 60 words

Electronic signal conversion apparatus as set forth in claim 1 wherein the voltage across the first capacitor is the analog voltage to which the digital value is converted and is substantially proportional to a first constant d to a power number N where N is substantially Proportional to the number of times that the first and second capacitors are connected.

Claim 6

Dependent Claim 41 words

Electronic signal conversion apparatus as set forth in claim 1 wherein the capacitance of the first capacitor divided by the sum of capacitance of the first and second capacitors is a ratio d representing a base of logarithms of the conversion.

Claim 7

Dependent Claim 19 words

Electronic signal conversion apparatus as set forth in claim 5 wherein the ratio d is between 0.85 and 0.99.

Claim 8

Dependent Claim 28 words

Electronic signal conversion apparatus as set forth in claim 1 wherein the capacitance of the first capacitor is at least ten times the capacitance of the second capacitor.

Claim 9

Dependent Claim 50 words

Electronic signal conversion apparatus as set forth in claim 1 wherein said means for operating said switch means includes counter means for continually incrementing a count and decoder means responsive to the count of said counter means for generating a series of control signals in sequence for said switch means.

Claim 10

Dependent Claim 226 words

Electronic conversion signal apparatus as set forth in claim 1 for use with a hearing aid comprising: microphone means for generating an electrical output from sounds external to a user of the hearing aid; electrically driven receiver means for emitting sound into the ear of the user of the hearing aid, some of the sound emitted by the receiver returning to the microphone means to add a feedback contribution to its electrical output; means, including said electronic conversion signal apparatus for converting the electrical output of the microphone means to a substantially logarithmic electrical representation; first means for combining the microphone output so converted with an adaptive output in logarithmic electrical representation to produce a combined signal input including a first polarity signal; means for electronic processing of the combined signal input in logarithmic form to produce a filtered signal in logarithmic form; means for generating a noise signal including a second polarity signal; and second means for combining the filtered signal with the noise signal for the receiver of the hearing aid, said means for electronic processing also including adaptive filter means for electronic processing of the filtered signal and the noise signal to produce an adaptive output in logarithmic form to said first means for combining to substantially offset the feedback contribution in the electrical output of the microphone means in the hearing aid.

Claim 11

Dependent Claim 78 words

A hearing aid as set forth in claim 9 wherein said adaptive filter means comprises all-hardware logarithmic digital filter means for processing the filtered signal and the noise signal in accordance with a series of digital parameters to produce the adaptive output in logarithmic form for said first means for combining; and logic circuit means for adaptively varying the digital parameters of the all-hardware logarithmic digital filter means so that the adaptive output substantially offsets the feedback contribution.

Claim 12

Dependent Claim 44 words

A hearing aid as set forth in claim 10 wherein said means for electronic processing also includes all-hardware digital filter-limit-filter means for processing the combined signal input in logarithmic form in accordance with a second series of digital parameters to produce the filtered signal.

Claim 13

Dependent Claim 93 words

Electronic signal conversion apparatus as set forth in claim 9 comprising: first and second VLSI dies; logarithmic analog-to-digital and digital-to-analog signal conversion means fabricated on said first VLSI die and including said first and second capacitors having respective electrical charges and means for redistributing the charges repeatedly a variable number of times, wherein the variable number relates digital to analog; and a logarithmic filter-limit-filter circuit fabricated on said second VLSI die and having a digital input and a digital output respectively connected to said logarithmic signal conversion means on said first VLSI die.

Claim 14

Dependent Claim 174 words

An electronic filter as set forth in claim 12 wherein said logarithmic filter-limit-filter circuit includes logarithmic filter means having a series of filter stages with inputs and outputs in cascade and respective means associated with said filter stages for storing electrical representations of filter parameters, said filter stages including means for respectively adding the electrical representations of the filter parameters to the digital input thereby producing a set of filter sum signals, at least one of said filter stages including means for producing a filter signal in substantially logarithmic form at its output by combining a filter sum signal for that filter stage with a signal from an output of another filter stage; limiting means, responsive to a signal from an output of a filter stage in said logarithmic filter means, for producing a limiter output signal generally limited to a predetermined range of electrical values; and means for multiplexing the limiter output signal with the digital input so that said logarithmic filter means operates as both a logarithmic prefilter and a logarithmic postfilter.

Claim 15

Dependent Claim 142 words

Electronic signal conversion apparatus as set forth in claim 13 wherein said limiting means comprises: storing means for holding an electrical representation of a boost value; means connected to said storing means for electrically increasing the electrical signal with the digital representation of the boost value, said means for electrically increasing producing a first output signal having a variable level depending on the magnitude of said boost value and the electrical signal and not exceeding a maximum output level of which said means for increasing is capable; and means, connected to said storing means and to said means for increasing, for decreasing the first output signal by the digital representation of said boost value to produce a limiter output which represents the same magnitude as the electrical signal unless the electrical signal exceeds a predetermined magnitude inversely related to the boost value.

Claim 16

Dependent Claim 132 words

Signal processing apparatus as set forth in claim 14 wherein said storing means includes means for holding a plurality of electrical representations of boost values and further comprising filter means having a series of filter stages in cascade and respective means associated with said filter stages for storing a plurality of electrical representations of filter parameter for each individual filter stage; and said multiplexing means includes means for multiplexing the operations of each individual filter stage for filtering with respect to each of the plurality of filter parameters for that individual filter stage and for concurrently multiplexing, for said means for increasing and said means for decreasing, the electrical representations of the boost values from said storing means so that the boost values for limiting purposes respectively correspond to particular filter parameters.

Claim 17

Dependent Claim 103 words

An electronic filter as set forth in claim 12 wherein said logarithmic filter-limit-filter circuit includes an electronic filter having a series of filter stage means responsive to the digital input and having inputs and outputs in cascade, means for storing electrical representations of filter parameters for said filter stage means, and said series of filter stage means including means for filtering signals through the series of filter stage means from a first to a last of said filter stage means and then filtering signals back through said series of filter stage means from the last to the first of said filter stage means.

Claim 18

Dependent Claim 35 words

An electronic filter as set forth in claim 12 further comprising adaptive logarithmic filter means fabricated on one of said VLSI dies and interconnected with said logarithmic signal conversion means and said logarithmic filter-limit-filter circuit.

Claim 19

Dependent Claim 128 words

Electronic signal conversion apparatus as set forth in claim 1 for use with a hearing aid comprising: microphone means for generating an electrical output from sounds external to a user of the hearing aid; and electrically drive receiver means for emitting sound into the ear of the user of the hearing aid; and a logarithmic filter-limit-filter circuit having a digital input and a digital output connected to said electronic signal conversion apparatus, said microphone output connected to said electronic signal conversion apparatus as analog input for conversion to digital form for the input of said logarithmic filter-limit-filter circuit and said receiver means connected elsewhere to said electronic signal conversion apparatus for conversion of the digital output of said logarithmic filter-limit-filter circuit to analog form for said receiver means.

Claim 20

Dependent Claim 102 words

A hearing aid as set forth in claim 18 further comprising a logarithmic filter-limit-filter circuit having a digital input and a digital output connected to said logarithmic signal conversion means, said microphone output connected to said logarithmic signal conversion means as analog input for conversion means, said microphone output connected to said logarithmic signal conversion means as analog input for conversion to digital form for the input of said logarithmic filter-limit-filter circuit and said receiver means connected elsewhere to said logarithmic signal conversion means for conversion of the digital output of said logarithmic filter-limit-filter circuit to analog form for said receiver means.

Claim 21

Dependent Claim 194 words

A digital-to-analog converter for use with an electrical source, comprising: counter means for holding a digital value which is to be converted to analog form; first and second capacitors; first switch means generally operable for charging said first capacitor to a first voltage from the electrical source; second switch means generally operable for discharging said second capacitor to a voltage level different from the voltage to which said first capacitor is charged; third switch means generally operable for connecting said first capacitor so charged to said second capacitor so that a redistribution of charge occurs and the voltage across said first capacitor is reduced to a predetermined fraction of the first voltage; and means responsive to said counter means for repeatedly operating said second and third switch means alternately so that three voltage across said first capacitor is repeatedly reduced by the predetermined fraction a number of times, the number being represented by the digital value held in said counter means, so that the voltage remaining across said first capacitor after being reduced for that number of times is an analog voltage which is representative of the digital value which is to be converted.

Claim 22

Dependent Claim 194 words

A digital-to-analog converter for use with an electrical source, comprising: counter means for holding a digital value which is to be converted to analog form; first and second capacitors; first switch means generally operable for charging said first capacitor to a first voltage from the electrical source; second switch means generally operable for discharging said second capacitor to a voltage level different from the voltage to which said first capacitor is charged; third switch means generally operable for connecting said first capacitor so charged to said second capacitor so that a redistribution of charge occurs and the voltage across said first capacitor is reduced to a predetermined fraction of the first voltage; and means responsive to said counter means for repeatedly operating said second and third switch means alternately so that three voltage across said first capacitor is repeatedly reduced by the predetermined fraction a number of times, the number being represented by the digital value held in said counter means, so that the voltage remaining across said first capacitor after being reduced for that number of times is an analog voltage which is representative of the digital value which is to be converted.

Claim 23

Dependent Claim 63 words

A method of operating a digital-to-analog converter as set forth in claim 20 wherein said means for repeatedly operating includes means for operating said second and forth switch means together and then operating said third and fifth switch means together so that voltage across said first capacitor is reduced with each operation repeatedly for the number of times represented by the digital value.

Claim 24

Independent Claim 161 words

A method of operating a digital-to-analog converter for converting a digital value to analog form using first and second capacitors and switches, comprising the steps of: charging the first capacitor to a first voltage from the source of voltage; discharging the second capacitor to a voltage level different from the voltage to which the first capacitor is charged; connecting the first capacitor so charged to the second capacitor so that a redistribution of charge occurs and the voltage across the first capacitor is reduced to a predetermined fraction of its previous voltage; and repeatedly performing the discharging and connecting steps alternately so that the voltage across said first capacitor is repeatedly reduced by the predetermined fraction a number of times, the number being represented by the digital value, so that the voltage remaining across said first capacitor after being reduced for that number of times is an analog voltage which is representative of the digital value which is to be converted.

Claim 25

Independent Claim 161 words

A method of operating a digital-to-analog converter for converting a digital value to analog form using first and second capacitors and switches, comprising the steps of: charging the first capacitor to a first voltage from the source of voltage; discharging the second capacitor to a voltage level different from the voltage to which the first capacitor is charged; connecting the first capacitor so charged to the second capacitor so that a redistribution of charge occurs and the voltage across the first capacitor is reduced to a predetermined fraction of its previous voltage; and repeatedly performing the discharging and connecting steps alternately so that the voltage across said first capacitor is repeatedly reduced by the predetermined fraction a number of times, the number being represented by the digital value, so that the voltage remaining across said first capacitor after being reduced for that number of times is an analog voltage which is representative of the digital value which is to be converted.

Claim 26

Dependent Claim 206 words

Electronic signal conversion apparatus comprising: means for temporarily holding a sample of an analog signal which is to be converted to a digital value; first and second capacitors, when the capacitance of the first capacitor divided by the sum of capacitance of the first and second capacitors is a ratio d representing a base of logarithms of the conversion, wherein the ratio d is between 0.85 and 0.99; switch means generally operable for executing selective operations including selectively charging at least one of the first and second capacitors, selectively discharging at least one of the first and second capacitors, and selectively connecting the first and second capacitors so that a redistribution of charge between them occurs; means for operating said switch means to make it perform a sequence of the selective operations among which operations the redistribution of charge repeatedly occurs a number of times until a predetermined electrical condition, involving the sample of the analog signal, occurs; and means for producing a digital value as a function of the number of times the redistribution of charge occurs, so that the digital value so produced when the operations are executed is representative of the digital value to which the sample of the analog signal is converted.

Claim 27

Dependent Claim 206 words

Electronic signal conversion apparatus comprising: means for temporarily holding a sample of an analog signal which is to be converted to a digital value; first and second capacitors, when the capacitance of the first capacitor divided by the sum of capacitance of the first and second capacitors is a ratio d representing a base of logarithms of the conversion, wherein the ratio d is between 0.85 and 0.99; switch means generally operable for executing selective operations including selectively charging at least one of the first and second capacitors, selectively discharging at least one of the first and second capacitors, and selectively connecting the first and second capacitors so that a redistribution of charge between them occurs; means for operating said switch means to make it perform a sequence of the selective operations among which operations the redistribution of charge repeatedly occurs a number of times until a predetermined electrical condition, involving the sample of the analog signal, occurs; and means for producing a digital value as a function of the number of times the redistribution of charge occurs, so that the digital value so produced when the operations are executed is representative of the digital value to which the sample of the analog signal is converted.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-07-05	1997-01-04	1997-07-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-07-05	2001-01-04	2001-07-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-07-05	2005-01-04	2005-07-06	$7700.00	Window Closed / Lapsed

Electronic filters, repeated signal charge conversion apparatus, hearing aids and methods

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag