Patent US4306222A successfully refreshed from Google Patents.
US4306222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
(b+a)-Bit D/A converter with b-bit auxiliary D/A converter
Assignee: US Philips Corp
•
Filing: 1979-10-29
•
Granted: 1981-12-15
•
Expires: 1999-10-29
Abstract
Abstract A digital-to-analog converter is described for converting (b+a)-bit code words into an analog signal by means of a b-bit auxiliary digital-to-analog converter. In order to reduce the quantizing noise introduced by the indispensible quantizing of the (b+a)-bit code words for obtaining the b-bit code words these (a+b)-bit code words are applied to an integrating network which has its output connected to an amplitude-limiting device which brings the integrated signal in the signal range of the auxiliary-D/A converter. The output signal of the amplitude-limiting device is now quantized and this quantizing signal is applied to the auxiliary D/A converter which produces analog output signal samples which are applied to, possibly, an analog output filter through a cascade arrangement of an amplitude-restorer and a difference network. The (b+a)-bit code words are assumed to occur with a frequency which is higher than the Nyquist sampling frequency associated with the analog signal represented by these (b+a)-bit code words.
Inventors
- 👤 Johannes B. H. Peek
- 👤 Wolfgang F. G. Mecklenbrauker
- 👤 Theodoor A. C. M. Claasen
- 👤 Nicolaas Van Hurck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:54
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/02; H04B14/04; H04B14/046; H03; H03M; H03M1/00; H03M1/06; H03M1/08; H03M1/0854; H03M1/66
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
188 words
A digital-to-analog converter for converting a digital signal, formed by a sequence of code-words, each having b+a bits, into an analog signal, characterized in that this digital-to-analog converter comprises: a converter input for receiving the digital signal; a converter output; means for integration and amplitude-limiting for producing a digital auxiliary signal which is an amplitude-limited version of the integrated digital signal applied to said means; first coupling means for coupling the input of the integration and amplitude-limiting means to a converter input; quantizing means connected to said integration and amplitude-limiting means for limiting the word length of the code words of the digital auxiliary signal for the generation of a quantizing means output signal formed by a sequence of code-words, each having b-bits; difference and amplitude-restoration means; second coupling means for coupling the input of the difference and amplitude-restoration means to the output of quantizing means; third coupling means for coupling the output of the difference and amplitude-restoration means to the converter output; a b-bit auxiliary digital-to-analog converter included in the circuit formed by the second coupling means, the difference and amplitude-restoration means and the third coupling means.
Claim 2
Dependent Claim
188 words
A digital-to-analog converter for converting a digital signal, formed by a sequence of code-words, each having b+a bits, into an analog signal, characterized in that this digital-to-analog converter comprises: a converter input for receiving the digital signal; a converter output; means for integration and amplitude-limiting for producing a digital auxiliary signal which is an amplitude-limited version of the integrated digital signal applied to said means; first coupling means for coupling the input of the integration and amplitude-limiting means to a converter input; quantizing means connected to said integration and amplitude-limiting means for limiting the word length of the code words of the digital auxiliary signal for the generation of a quantizing means output signal formed by a sequence of code-words, each having b-bits; difference and amplitude-restoration means; second coupling means for coupling the input of the difference and amplitude-restoration means to the output of quantizing means; third coupling means for coupling the output of the difference and amplitude-restoration means to the converter output; a b-bit auxiliary digital-to-analog converter included in the circuit formed by the second coupling means, the difference and amplitude-restoration means and the third coupling means.
Claim 3
Dependent Claim
43 words
A digital-to-analog converter as claimed in claim 1, characterized in that the function which describes the relationship between the auxiliary signal produced by the integration and amplitude-limiting means and the integrated value of the signal applied to this means is a periodic function.
Claim 4
Dependent Claim
86 words
A digital-to-analog converter as claimed in claim 1, characterized in that the relationship between the digital auxiliary signal {y(n)} produced by the integration and amplitude-limiting means and the digital signal {x'(n)} of these means is given by the relation ##EQU8## wherein: η and R each represent a random real and positive number n and i each represent an integral number wherein -≦<n<∞ and -∞<i<∞ k n represents an integral and positive number and has such a value that -A<y(n)<A, wherein A is a suitable positive number.
Claim 5
Dependent Claim
34 words
A digital-to-analog converter as claimed in claim 3, characterized in that the integration and amplitude-limiting means comprise means for generating a digital signal which is representative of the difference k n -k n-1 .
Claim 6
Dependent Claim
58 words
A digital-to-analog converter as claimed in claim 4, characterized in that it further comprises means for generating a signal which is representative of the product (k n -k n-1 )RV max , RV max representing a constant reference signal, these means being coupled to said integration and amplitude-limiting means and to a second input of said adding means.
Claim 7
Dependent Claim
42 words
A digital-to-analog converter as claimed in claim 1, characterized in that said amplitude-restoration means are formed by an adding device which has a first input connected to the output of the difference means and its output connected to said third coupling means.
Claim 8
Dependent Claim
64 words
A digital-to-analog converter as claimed in claim 5, characterized in that the output of the difference means is also connected to a polarity detector circuit which controls a switching device through which either a first or a second reference signal of constant value is applied to a second input of the adding device in dependence on the polarity of the difference means output signal.
Claim 9
Dependent Claim
27 words
A digital-to-analog converter as claimed in claim 1, characterized in that said first coupling means comprise an adding device to which a reference code word is applied.
Claim 10
Dependent Claim
20 words
A digital-to-analog converter as claimed in claim 1, characterized in that said first coupling means comprise an interpolating digital filter.
References Cited (Backward Citations)
US3560957A
Cited
US3893102A
Cited
US4006475A
Cited
US3987436A
Cited
US4079373A
Cited
US4131764A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-14 | 1985-06-15 | 1985-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-14 | 1989-06-15 | 1989-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-14 | 1993-06-15 | 1993-12-15 | $7700.00 | Window Closed / Lapsed |