US5550544A
Expired / Lapsed
US
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Signal converter, noise shaper, AD converter and DA converter
Assignee: Panasonic Holdings Corp
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Filing: 1994-02-23
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Granted: 1996-08-27
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Expires: 2014-02-23
Abstract
Abstract The present invention provides a first-order delta-sigma AD converter adapted to conduct noise shaping and having a quantizer arranged such that, when the amplitude of an input signal entered into the quantizer is small, the amplitude of a difference signal between the input signal entered into the quantizer and an output signal therefrom, is small. It is therefore possible to achieve an efficient AD- or DA-converter reduced in power consumption, which satisfies the transmission characteristics of the specifications of CCITT G.714 based on a method of PCM-encoding an audio frequency band signal stipulated in the specifications of CCITT G.711.
Inventors
- 👤 Shiro Sakiyama
- 👤 Shiro Dosho
- 👤 Masakatsu Maruyama
- 👤 Hiroyuki Nakahira
- 👤 Toshiyuki Shono
- 👤 Akira Matsuzawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:42
CPC Classifications
H; H03; H03M; H03M3/00; H03M3/30; H03M3/39; H03M3/412; H03M3/422; H03M3/424; H03M3/436; H03M3/456
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
73 words
A signal converter comprising a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals, said (n-1) reference levels in said quantizer being set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and an output signal of said quantizer.
Claim 2
Dependent Claim
73 words
A signal converter comprising a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals, said (n-1) reference levels in said quantizer being set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and an output signal of said quantizer.
Claim 3
Dependent Claim
135 words
In an oversampling noise shaper comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying a digital output signal of said quantizer by a preset period of time; and signal accumulating means for accumulating each difference signal between each external input signal and each output signal of said delay device, an output signal of said signal accumulating means being entered into said quantizer; said oversampling noise shaper characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 4
Dependent Claim
135 words
In an oversampling noise shaper comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying a digital output signal of said quantizer by a preset period of time; and signal accumulating means for accumulating each difference signal between each external input signal and each output signal of said delay device, an output signal of said signal accumulating means being entered into said quantizer; said oversampling noise shaper characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 5
Dependent Claim
160 words
In a noise shaping AD converter comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying a digital output signal of said quantizer by a preset period of time; a DA converting circuit for converting an n-level digital output signal of said delay device into an n-level analog signal; and signal accumulating means for accumulating each difference signal between each external analog input signal and each analog signal supplied from said DA converting circuit, an output signal of said signal accumulating means being entered into said quantizer; said noise shaping AD converter characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 6
Dependent Claim
160 words
In a noise shaping AD converter comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying a digital output signal of said quantizer by a preset period of time; a DA converting circuit for converting an n-level digital output signal of said delay device into an n-level analog signal; and signal accumulating means for accumulating each difference signal between each external analog input signal and each analog signal supplied from said DA converting circuit, an output signal of said signal accumulating means being entered into said quantizer; said noise shaping AD converter characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitudes for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 7
Dependent Claim
160 words
In a noise shaping DA converter comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying an n-level digital output signal of said quantizer by a preset period of time; signal accumulating means for accumulating each difference signal between each external digital input signal and each digital signal supplied from said delay device, an output signal of said signal accumulating means being entered into said quantizer; and a DA converting circuit for converting said n-level digital output signal of said quantizer into an n-level analog signal; said noise shaping DA converter characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitude levels for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 8
Dependent Claim
160 words
In a noise shaping DA converter comprising: a quantizer in which an input signal is compared with each of preset (n-1) reference levels and quantized into one of n-digital output signals; a delay device for delaying an n-level digital output signal of said quantizer by a preset period of time; signal accumulating means for accumulating each difference signal between each external digital input signal and each digital signal supplied from said delay device, an output signal of said signal accumulating means being entered into said quantizer; and a DA converting circuit for converting said n-level digital output signal of said quantizer into an n-level analog signal; said noise shaping DA converter characterized in that said (n-1) reference levels in said quantizer are set such that there are present, according to the amplitude of said input signal, a plurality of average amplitude levels for a difference signal representing a difference between said input signal and said output signal of said quantizer.
Claim 9
Dependent Claim
69 words
A signal converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 1 to 4, wherein the (n-1) reference levels in the quantizer are set such that the average amplitude of a difference signal representing a difference between the input signal and the output signal of said quantizer is small when the amplitude of said input signal is small.
Claim 10
Dependent Claim
78 words
A signal converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 1 to 4, wherein the (n-1) reference levels in the quantizer are set such that the interval between adjacent reference levels is narrower as the amplitude of the input signal is closer to zero, and the interval between adjacent reference levels is broader as the absolute value of said amplitude of said input signal is greater.
Claim 11
Dependent Claim
52 words
A signal converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 1 to 4, wherein the (n-1) reference levels in the quantizer are 4-level values of -1/4, -1/32, +1/32 and +1/4 with respect to the maximum amplitude of the input signal.
Claim 12
Dependent Claim
69 words
A signal converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 1 to 4, wherein the (n-1) reference levels in the quantizer are set such that the average amplitude of a difference signal representing a difference between the input signal and the output signal of said quantizer, is great when the amplitude of said input signal is small.
Claim 13
Dependent Claim
54 words
A converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 2 to 4, wherein the number of the signal accumulating means is one and said noise shaper, said noise shaping AD converter or said noise shaping DA converter is of the delta-sigma type.
Claim 14
Dependent Claim
60 words
A signal converter, a noise shaper, a shaping AD converter or a noise shaping DA converter according to any of claims 2 to 4, wherein a plurality of signal accumulating means are disposed and connected in series to one another and said noise shaper, said noise shaping AD converter or said noise shaping DA converter is of the delta-sigma type.
Claim 15
Dependent Claim
42 words
A noise shaper, a noise shaping AD converter or a noise shaping DA converter according to any of claims 2 to 4, wherein said noise shaper, said noise shaping AD converter or said noise shaping DA converter is of the delta-sigma type.
Claim 16
Dependent Claim
47 words
A signal converter, a noise shaper noise shaping AD converter or a noise shaping DA converter according to claim 5, wherein the (n-1) reference levels in the quantizer are 4-level values of -1/4, -1/32, +1/32 and +1/4 with respect to the maximum amplitude of the input signal.
Claim 17
Dependent Claim
48 words
A signal converter, a noise shaper, a noise shaping AD converter or a noise shaping DA converter according to claim 6, wherein the (n-1) reference levels in the quantizer are 4-level values of -1/4, -1/32, +1/32 and +1/4 with respect to the maximum amplitude of the input signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-08-27 | 2000-02-26 | 2000-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-27 | 2004-02-26 | 2004-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-27 | 2008-02-26 | 2008-08-27 | $7700.00 | Window Closed / Lapsed |