US4857927A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dither circuit having dither level changing function
Assignee: Yamaha Corp
•
Filing: 1986-12-16
•
Granted: 1989-08-15
•
Expires: 2006-12-16
Abstract
Abstract A dither circuit for improving linearity in A/D or D/A conversion by adding dither to an input signal of an A/D or D/A converter and subtracting dither from an output signal of the A/D or D/A converter. The dither circuit comprises a dither generator for supplying dither to the input and output signals for addition and subtraction of the dither and dither level changing means for detecting the level of the input signal to the A/D or D/A converter for controlling the dither generator to change the level of dither supplied by the dither generator, in accordance with the level of the input signal. The level of dither is controlled to increase as the level of the input signal decreases and to decrease as the level of the input signal increases.
Inventors
- 👤 Osamu Takabayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:09
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/06; H03M1/0617; H03M1/0634; H03M1/0636; H03M1/0639
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
86 words
A dither circuit comprising: and A/D converter; an adder provided in a prior stage to said A/D converter; a subtractor provided in a posterior stage to said A/D converter; a dither generator for supplying dither to said adder and subtractor and, dither level changing means for detecting the level of an input signal to said A/D converter for controlling said dither generator to change the level of dither supplied by said dither generator in accordance with the level of the input signal to said A/D converter.
Claim 2
Dependent Claim
86 words
A dither circuit comprising: and A/D converter; an adder provided in a prior stage to said A/D converter; a subtractor provided in a posterior stage to said A/D converter; a dither generator for supplying dither to said adder and subtractor and, dither level changing means for detecting the level of an input signal to said A/D converter for controlling said dither generator to change the level of dither supplied by said dither generator in accordance with the level of the input signal to said A/D converter.
Claim 3
Dependent Claim
65 words
A dither circuit as defined in claim 1 wherein said dither level changing means controls the level of dither stepwise in accordance with the level of the input signal to said A/D converter in such a manner that the level of dither increases as the level of the input signal decreases and the level of dither decreases as the level of the input signal increases.
Claim 4
Dependent Claim
66 words
A dither circuit as defined in claim 1 wherein said dither level changing means continuously variably controls the level of dither in accordance with the level of the input signal to said A/D converter in such a manner that the level of dither increases as the level of the input signal decreases and the level of dither decreases as the level of the input signal increases.
Claim 5
Dependent Claim
61 words
A dither circuit as defined in claim 2 wherein said dither level changing means reduces the level of dither supplied from said dither generator to zero when the level of the input signal to said A/D converter has reached a predetermined level above which clipping occurs in the input signal to said A/D converter which has been superposed with the dither.
Claim 6
Dependent Claim
61 words
A dither circuit as defined in claim 3 wherein said dither level changing means reduces the level of dither supplied from said dither generator to zero when the level of the input signal to said A/D converter has reached a predetermined level above which clipping occurs in the input signal to said A/D converter which has been superposed with the dither.
Claim 7
Dependent Claim
42 words
A dither circuit as defined in claim 1 wherein said dither level changing means comprises a level detector provided in a posterior stage to said subtractor for detecting the level of the input signal to said A/D converter after subtraction of dither.
Claim 8
Dependent Claim
42 words
A dither circuit as defined in claim 1 wherein said dither level changing means comprises a level detector provided in a prior stage to said adder for detecting the level of the input signal to said A/D converter before addition of dither.
Claim 9
Dependent Claim
16 words
A dither circuit as defined in claim 6 wherein said level detector comprises a window comparator.
Claim 10
Dependent Claim
16 words
A dither circuit as defined in claim 7 wherein said level detector comprises a window comparator.
Claim 11
Dependent Claim
86 words
A dither circuit comprising: a D/A converter; an adder provided in a prior stage to said D/A converter; a substractor provided in a posterior stage to said D/A converter; a dither generator for supplying dither to said adder and subtractor; and dither level changing means for detecting the level of an input signal to said D/A converter for controlling said dither generator to change the level of dither supplied by said dither generator in accordance with the level of the input signal to said D/A converter.
Claim 12
Dependent Claim
86 words
A dither circuit comprising: a D/A converter; an adder provided in a prior stage to said D/A converter; a substractor provided in a posterior stage to said D/A converter; a dither generator for supplying dither to said adder and subtractor; and dither level changing means for detecting the level of an input signal to said D/A converter for controlling said dither generator to change the level of dither supplied by said dither generator in accordance with the level of the input signal to said D/A converter.
Claim 13
Dependent Claim
65 words
A dither circuit as defined in claim 10 wherein said dither level changing means controls the level of dither stepwise in accordance with he level of the input signal to said D/A converter in such a manner that the level of dither increases as the level of the input signal decreases and the level of dither decreases as the level of the input signal increases.
Claim 14
Dependent Claim
66 words
A dither circuit as defined in claim 10 wherein said dither level changing means continously variably controls the level of dither in accordance with the level of the input signal to said D/A converter in such a manner that the level of dither increases as the level of the input signal decreases and the level of dither decreases as the level of the input signal increases.
Claim 15
Dependent Claim
60 words
A dither as defined in claim 11 wherein said dither level changing means reduces the level of dither supplied from said dither generator to zero when the level of the input signal to said D/A converter has reached a predetermined level above which clipping occurs in the input signal to said D/A converter which has been superposed with the dither.
Claim 16
Dependent Claim
60 words
A dither circuits defined in claim 12 wherein said dither level changing means reduces the level of dither supplied from said dither generator to zero when the level of the input signal to said D/A converter has reached a predetermined level above which clipping occurs in the input signal to said D/A converter which has been superposed with the dither.
Claim 17
Dependent Claim
42 words
A dither circuit as defined in claim 10 wherein said dither level changing means comprises a level detector provided in a posterior stage to stage subtractor for detecting the level of the input signal to said D/A converter after subtraction of dither.
Claim 18
Dependent Claim
42 words
A dither circuit as defined in claim 10 wherein said dither level changing means comprises a level detector provided in a prior stage to said adder for detecting the level of the input signal to said D/A converter before addition of dither.
Claim 19
Dependent Claim
16 words
A dither circuit as defined in claim 15 wherein said level detector comprises a window comparator.
Claim 20
Dependent Claim
16 words
A dither circuit as defined in claim 16 wherein said level detector comprises a window comparator.
References Cited (Backward Citations)
US3577123A
Cited
US4490714A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-14 | 1993-02-13 | 1993-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-14 | 1997-02-13 | 1997-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-14 | 2001-02-13 | 2001-08-15 | $7700.00 | Window Closed / Lapsed |