US3699568A
Expired / Lapsed
US
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Weighted ladder technique
Assignee: Motorola Solutions Inc
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Filing: 1970-12-21
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Granted: 1972-10-17
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Expires: 1990-12-21
Abstract
Abstract There is disclosed a weighted ladder network for use in digital to analog converters which s characterized by faster speeds than the common R/2R and binary ladder configurations for the same total power consumption. The technique involves splitting up a conventional ladder network into two separate sections. The first section is a conventional binary ladder driven by equal current sources. The second section, however, involves weighting the resistance elements and the current sources in such a manner that the total resistance of the circuit is minimized.
Inventors
- 👤 James E Thompson
- 👤 Gerald J D Amato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:57
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/10; H03M1/1009
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
228 words
A ladder network for providing a series of binary weighted currents comprising: a first section having a first number of series connected resistive elements weighted in a binary fashion and a like number of current sources each generating a current equal numerically to the resistance of the first resistive element in said series, said current sources adapted to be connected between a reference potential and one end of a corresponding resistive element; and a second section, connected in series with said first section and having a second number of series connected resistive elements, each having a resistance equal to a predetermined number, and a like number of current sources, the current sources in said second section adapted to be connected between said reference potential and one end of a corresponding resistive element in said second series, the current source adapted to be connected to the last of the elements in said second number generating a current equal to said predetermined number, and the remaining current sources in said second section generating those currents which will provide binary weighted voltages between the free end of said last resistive element and said reference potential, when they are connected to their respective resistive elements, whereby the resistance ratio of said network can be minimized such that said network has a low settling time and can be fabricated in integrated circuit form.
Claim 2
Dependent Claim
228 words
A ladder network for providing a series of binary weighted currents comprising: a first section having a first number of series connected resistive elements weighted in a binary fashion and a like number of current sources each generating a current equal numerically to the resistance of the first resistive element in said series, said current sources adapted to be connected between a reference potential and one end of a corresponding resistive element; and a second section, connected in series with said first section and having a second number of series connected resistive elements, each having a resistance equal to a predetermined number, and a like number of current sources, the current sources in said second section adapted to be connected between said reference potential and one end of a corresponding resistive element in said second series, the current source adapted to be connected to the last of the elements in said second number generating a current equal to said predetermined number, and the remaining current sources in said second section generating those currents which will provide binary weighted voltages between the free end of said last resistive element and said reference potential, when they are connected to their respective resistive elements, whereby the resistance ratio of said network can be minimized such that said network has a low settling time and can be fabricated in integrated circuit form.
Claim 3
Dependent Claim
32 words
The ladder network as recited in claim 1 wherein said ladder contains an odd number of resistive elements and wherein said first section contains one less resistive element than said second section.
Claim 4
Dependent Claim
18 words
The ladder network as recited in claim 1 wherein each section contains an equal number of resistive elements.
Claim 5
Dependent Claim
33 words
The ladder network as recited in claim 3 wherein said predetermined number is given by solving the following formula for Rho where n is the total number of resistive elements in said network.
Claim 6
Dependent Claim
45 words
The ladder network as recited in claim 4 wherein the current generated by a given current source is given by the following formula where Ik is the current in the kth current source, whereby the resistance ratio of said ladder network is at a minimum.
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) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |