US5179380A
Expired / Lapsed
US
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One-bit sigma-delta modulator with improved signal stability
Assignee: Boeing Co
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Filing: 1992-02-07
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Granted: 1993-01-12
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Expires: 2012-02-07
Abstract
Abstract The one-bit sigma-delta modulator with improved signal stability disclosed herein includes, in order, a first anti-aliasing filter (20), a chopper (22), a second anti-aliasing filter (30), and a one-bit modulator (32). The chopper (22) and one-bit modulator (32) are driven by a clock generator (38). The chopper (22) is introduced to provide a carrier upon which the signal may ride, thereby eliminating dc stability problems. The first anti-aliasing filter (20) eliminates aliasing from the chopper (22), and the second anti-aliasing filter (30) eliminates aliasing from the one-bit modulator (32). The second anti-aliasing filter (30) may be eliminated if the frequency of the chopper (22) is an exact integer submultiple of the sampling frequency of the one-bit modulator (32). This invention may drive a decimation filter (36), also driven by the clock generator (38), to provide a low cost analog-to-digital converter.
Inventors
- 👤 Stanley A. White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:54
CPC Classifications
H; H03; H03M; H03M3/00; H03M3/30; H03M3/322; H03M3/324; H03M3/344; H03M3/326; H03M3/338; H03M3/34; H03M3/39; H03M3/412; H03M3/422; H03M3/43
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
174 words
A method for one-bit sigma-delta modulating an input signal, the method comprising the steps of: (a) producing a first filter signal by first anti-alias filtering the input signal, the first anti-alias filtering step providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) producing a chopper signal by chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi; (c) producing a second filter signal by second anti-alias filtering the chopper signal, the second anti-alias filtering step providing: (1) a flat gain over a band of frequencies from fc-fi to fc+fi; and (2) a second cutoff frequency f2 which is less than fs-fc-2fi; and (d) producing a modulator output signal by one-bit modulating the second filter signal with the sampling signal.
Claim 2
Independent Claim
174 words
A method for one-bit sigma-delta modulating an input signal, the method comprising the steps of: (a) producing a first filter signal by first anti-alias filtering the input signal, the first anti-alias filtering step providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) producing a chopper signal by chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi; (c) producing a second filter signal by second anti-alias filtering the chopper signal, the second anti-alias filtering step providing: (1) a flat gain over a band of frequencies from fc-fi to fc+fi; and (2) a second cutoff frequency f2 which is less than fs-fc-2fi; and (d) producing a modulator output signal by one-bit modulating the second filter signal with the sampling signal.
Claim 3
Dependent Claim
16 words
The method of claim 1, wherein the first cutoff frequency fl is approximately equal to 2fc-2fi.
Claim 4
Dependent Claim
16 words
The method of claim 1, wherein the second cutoff frequency f2 is approximately equal to fs-fc-2fi.
Claim 5
Dependent Claim
19 words
The method of claim 1, further comprising the step of decimating/demodulating the modulator output signal with the sampling signal.
Claim 6
Independent Claim
139 words
A method for one-bit sigma-delta modulating an input signal, the method comprising the steps of: (a) producing a first filter signal by first anti-alias filtering the input signal, the first anti-alias filtering step providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) producing a chopper signal by chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi and by fc being an exact integer submultiple of fs; and (c) producing a modulator output signal by one-bit modulating the chopper signal with the sampling signal.
Claim 7
Independent Claim
139 words
A method for one-bit sigma-delta modulating an input signal, the method comprising the steps of: (a) producing a first filter signal by first anti-alias filtering the input signal, the first anti-alias filtering step providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) producing a chopper signal by chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi and by fc being an exact integer submultiple of fs; and (c) producing a modulator output signal by one-bit modulating the chopper signal with the sampling signal.
Claim 8
Dependent Claim
16 words
The method of claim 5, wherein the first cutoff frequency fl is approximately equal to 2fc-2fi.
Claim 9
Dependent Claim
19 words
The method of claim 5, further comprising the step of decimating/demodulating the modulator output signal with the sampling signal.
Claim 10
Independent Claim
187 words
An apparatus for one-bit sigma-delta modulating an input signal, the apparatus comprising: (a) means for producing a first filter signal, comprising means for first anti-alias filtering the input signal, the first anti-alias filtering means providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) means for producing a chopper signal, comprising means for chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi; (c) means for producing a second filter signal, comprising means for second anti-alias filtering the chopper signal, the second anti-alias filtering means providing: (1) a flat gain over a band of frequencies from fc-fi to fc+fi; and (2) a second cutoff frequency f2 which is less than fs-fc-2fi; and (d) means for producing a modulator output signal, comprising means for one-bit modulating the second filter signal with the sampling signal.
Claim 11
Independent Claim
187 words
An apparatus for one-bit sigma-delta modulating an input signal, the apparatus comprising: (a) means for producing a first filter signal, comprising means for first anti-alias filtering the input signal, the first anti-alias filtering means providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) means for producing a chopper signal, comprising means for chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi; (c) means for producing a second filter signal, comprising means for second anti-alias filtering the chopper signal, the second anti-alias filtering means providing: (1) a flat gain over a band of frequencies from fc-fi to fc+fi; and (2) a second cutoff frequency f2 which is less than fs-fc-2fi; and (d) means for producing a modulator output signal, comprising means for one-bit modulating the second filter signal with the sampling signal.
Claim 12
Dependent Claim
16 words
The apparatus of claim 8, wherein the first cutoff frequency fl is approximately equal to 2fc-2fi.
Claim 13
Dependent Claim
16 words
The apparatus of claim 8, wherein the second cutoff frequency f2 is approximately equal to fs-fc-2fi.
Claim 14
Dependent Claim
17 words
The apparatus of claim 8, further comprising means for decimating/demodulating the modulator signal with the sampling signal.
Claim 15
Independent Claim
148 words
An apparatus for one-bit sigma-delta modulating an input signal, the apparatus comprising: (a) means for producing a first filter signal, comprising means for first anti-alias filtering the input signal, the first anti-alias filtering means providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) means for producing a chopper signal, comprising means for chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi and by fc being an exact integer submultiple of fs; and (c) means for producing a modulator output signal, comprising means for one-bit modulating the chopper signal with the sampling signal.
Claim 16
Independent Claim
148 words
An apparatus for one-bit sigma-delta modulating an input signal, the apparatus comprising: (a) means for producing a first filter signal, comprising means for first anti-alias filtering the input signal, the first anti-alias filtering means providing: (1) a flat gain over a baseband of frequencies, the absolute values of which are less than or equal to some pre-selected input frequency fi; and (2) a first cutoff frequency fl; (b) means for producing a chopper signal, comprising means for chopping the first filter signal at a chopping frequency fc determined by a clock generator, the clock generator being connected to produce a sampling signal at a sampling frequency fs, and fc being characterized by fl being less than 2fc-2fi and by fc being an exact integer submultiple of fs; and (c) means for producing a modulator output signal, comprising means for one-bit modulating the chopper signal with the sampling signal.
Claim 17
Dependent Claim
16 words
The apparatus of claim 12, wherein the first cutoff frequency fl is approximately equal to 2fc-2fi.
Claim 18
Dependent Claim
17 words
The apparatus of claim 12, further comprising means for decimating/demodulating the modulator signal with the sampling 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) | 1996-01-12 | 1996-07-13 | 1997-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-01-12 | 2000-07-13 | 2001-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-01-12 | 2004-07-13 | 2005-01-12 | $7700.00 | Window Closed / Lapsed |