US 6,504,875 B2 · Apparatus for multilevel signaling

Abstract

A system for transmitting information from a source to a destination using multilevel signaling. Multiple conductors are coupled between the transmission source and the transmission destination. Multiple drivers are coupled to the conductors at the transmission source. Each driver is coupled to a pair of conductors. Multiple comparators are coupled to the conductors at the transmission destination. Each comparator is coupled to a pair of conductors. The information is encoded into a sequence of symbols in which each symbol represents a unique permutation of signal levels on the conductors. Each signal level is used at least once for each symbol. All signal levels associated with a particular symbol are transmitted over the conductors simultaneously.

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Drawings

Claims30

Dependent claims

A signaling system comprising:

a first and a second plurality of switches, wherein each switch of the first and second plurality of switches is coupled to a corresponding current source, wherein, in response to one of a plurality of control signals, one of first and second terminals of each switch of the first and second plurality of switches is coupled to the corresponding current source;
a first plurality of conductors, each conductor of the first plurality of conductors having a first end and a second end wherein each first end is coupled to different pairs of switches of the first plurality of switches;
a second plurality of conductors, each conductor of the second plurality of conductors having a first end and a second end wherein each first end is coupled to different pairs of switches of the second plurality of switches;
and
a first and a second plurality of comparators, each comparator of the first and second plurality of comparators having a first input and a second input wherein the first and second inputs of the first plurality of comparators are coupled to different pairs of second ends of the first plurality of conductors and the first and second inputs of the second plurality of comparators are coupled to different pairs of second ends of the second plurality of conductors.

2 more elements

A signaling system comprising:

a first translator to receive a plurality of digital signals, wherein the first translator generates a plurality of control signals based on the plurality of digital signals;
a first switch electrically coupled to a first end of a first conductor, the first switch to provide a first voltage level on the first conductor in response to a first control signal of the plurality of control signals;
a second switch electrically coupled to a first end of a second conductor, the second switch to provide a second voltage level on the second conductor in response to a second control signal of the plurality of control signals, and wherein the second voltage level is different than the first voltage level;
a third switch electrically coupled to a first end of a third conductor, the third switch to provide a third voltage level on the third conductor in response to a third control signal of the plurality of control signals, and wherein the third voltage level is different than the second voltage level;
and
a fourth switch electrically coupled to a first end of a fourth conductor, the fourth switch to provide one of the first, second and third voltage levels on the fourth conductor in response to a fourth control signal of the plurality of control signals.

3 more elements

A transmitter circuit to transmit multi-level signals, the transmitter circuit comprising:

a translator circuit to receive a plurality of binary signals, the translator circuit to generate first through sixth control signals in response to the plurality of binary signals;
a first switch having first and second terminals, wherein one of the first and second terminals of the first switch is coupled to a first current source in response to the first control signal;
a second switch having first and second terminals, wherein one of the first and second terminals of the second switch is coupled to a second current source in response to the second control signal;
a third switch having first and second terminals, wherein one of the first and second terminals of the third switch is coupled to a third current source in response to the third control signal;
a fourth switch having first and second terminals, wherein one of the first and second terminals of the fourth switch is coupled to a fourth current source in response to the fourth control signal;
a fifth switch having first and second terminals, wherein one of the first and second terminals of the fifth switch is coupled to a fifth current source in response to the fifth control signal;
a sixth switch having first and second terminals, wherein one of the first and second terminals of the third switch is coupled to a first current source in response to the sixth control signal;
a first output terminal coupled to the first terminal of the first switch and the second terminal of the second switch;
a second output terminal coupled to the second terminal of the first switch and the first terminal of the third switch;
a third output terminal coupled to the first terminal of the second switch and the second terminal of the third switch;
a fourth output terminal coupled to the first terminal of the fourth switch and the second terminal of the fifth switch;
a fifth output terminal coupled to the second terminal of the fourth switch and the first terminal of the sixth switch;
and
a sixth output terminal coupled to the first terminal of the fifth switch and the second terminal of the sixth switch.

11 more elements

A receiver circuit to receive a plurality of multi-level signals, the receiver circuit comprising:

first through sixth input terminals to receive the plurality of multi-level signals;
a first comparator having a first input, a second input and an output terminal, wherein the first input of the first comparator is coupled to the first input terminal, and the second input of the first comparator is coupled to the second input terminal;
a second comparator having a first input, a second input and an output terminal, wherein the first input of the second comparator is coupled to the third input terminal, and the second input of the second comparator is coupled to the first input terminal;
a third comparator having a first input, a second input and an output terminal, wherein the first input of the third comparator is coupled to the second input terminal, and the second input of the third comparator is coupled to the third input terminal;
a fourth comparator having a first input, a second input and an output terminal, wherein the first input of the fourth comparator is coupled to the fourth input terminal, and the second input of the fourth comparator is coupled to the fifth input terminal;
a fifth comparator having a first input, a second input and an output terminal, wherein the first input of the fifth comparator is coupled to the sixth input terminal, and the second input of the fifth comparator is coupled to the fourth input terminal;
a sixth comparator having a first input, a second input and an output terminal, wherein the first input of the sixth comparator is coupled to the fifth input terminal, and the second input of the sixth comparator is coupled to the sixth input terminal;
and
a translator coupled to the output terminals of the first through sixth comparators, the translator to generate a plurality of binary signals based on comparison results generated by the first through sixth comparators.

6 more elements

A transmitter circuit to transmit multi-level signals, the transmitter circuit comprising:

a first current source coupled to a first switch, the first switch having a first terminal and a second terminal, wherein, in response to a first control signal, the first current source is coupled to one of the first and second terminals of the first switch;
a second current source coupled to a second switch, the second switch having a first terminal and a second terminal, wherein, in response to a second control signal, the second current source is coupled to one of the first and second terminals of the second switch;
a third current source coupled to a third switch, the third switch having a first terminal and a second terminal, wherein, in response to a third control signal, the third current source is coupled to one of the first and second terminals of the third switch;
a fourth current source coupled to a fourth switch, the fourth switch having a first terminal and a second terminal, wherein, in response to a fourth control signal, the fourth current source is coupled to one of the first and second terminals of the fourth switch;
a first output terminal coupled to the first terminal of the first switch and the second terminal of the fourth switch;
a second output terminal coupled to the second terminal of the first switch and the first terminal of the second switch;
a third output terminal coupled to the first terminal of the third switch and the second terminal of the second switch;
and
a fourth output terminal coupled to the first terminal of the fourth switch and the second terminal of the third switch.

6 more elements

Dependencies are inferred from the claim text.

Description7,901 words

Summary817 words

#The present invention relates to a multilevel signaling system for transmitting signals across a multiconductor transmission line.

#Various techniques and systems are available for transmitting data between a source and a destination. When data is electrically transmitted across a conductor, a particular signaling technology or protocol is utilized. A set of symbols may be associated with specific signaling technologies. The symbols are used to encode the data into various electrical patterns on the transmission line conductors such that each symbol may be distinguished from other signals by analyzing the electrical pattern on the conductors. The conductors used to transmit data include wires, cables, traces on printed circuit boards, conductors embedded within a substrate, and various other conductive materials.

#In certain data transmission systems, the conductors are treated as transmission lines and analyzed by considering various electrical and electromagnetic wave properties and characteristics. In these systems, the signaling technology may include the coupling of signal drivers, signal receivers, conductors, and termination devices.

Brief description of the drawings17 figures

#The present invention is illustrated by way of example in the following drawings in which like references indicate similar elements. The following drawings disclose various embodiments of the present invention for purposes of illustration only and are not intended to limit the scope of the invention.

#FIG. 1 illustrates a known differential transmission system using a pair of conductors.

#FIG. 2 illustrates an embodiment of a system capable of performing multilevel signaling according to the present invention.

Detailed description6,763 words

#The following detailed description sets forth numerous specific details to provide a thorough understanding of the invention. However, those skilled in the art will appreciate that the invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the invention.

#The present invention is related to a multilevel signaling system that utilizes multiple transmission lines to transmit information from a source to a destination. Information is transmitted using symbols (or codes) formed from multiple signal levels. A signal level is the physical state of a conductor that can be determined by a detector coupled to the conductor. The symbols are defined such that the sum of the currents flowing on any group of conductors is constant for all symbols.

#Two or more possible signal levels are carried by each conductor. These signal levels may, for example, be generated by different currents flowing through the conductors. Different symbols are transmitted across the multiple conductors by using a permutation of the signal levels. For example, three different current values i0, i1, and i2 may be available for any particular conductor. Based on the combination of current values provided on each conductor, a specific symbol is represented. For example, Table 1 below illustrates a symbol set for use with a three-conductor transmission system using three different current values. The transmission system maintains a constant current on the conductors by providing each of the current values on one of the conductors; i.e., current i0 is provided on one conductor, current i1 is provided on another conductor, and current i2 is provided on the remaining conductor. Therefore, the sum of the currents flowing on the conductors for any symbol is i0+i1+i2. The use of constant current on the signal conductors reduces ground bounce. Ground bounce is the shift in the ground reference voltage due to output switching. If a terminating voltage is used in a termination network, noise on the voltage in the termination network is reduced, thereby providing a better signal-to-noise ratio in the system.

Facts

Application

09/999,812Filed 31 Oct 2001 · continuation

Priority

20 Dec 1996

Published

US 2002/0186777 A112 Dec 2002

Granted

7 Jan 2003

Term ended

20 Dec 2016

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification5 codes

H04L 25/0272
Arrangements for coupling to transmission lines: arrangements for coupling to multiple lines, e.g. for differential transmission
H04L 5/20
Arrangements affording multiple use of the transmission path: using different combinations of lines, e.g. phantom working
H04L 25/028
Arrangements for coupling to transmission lines: arrangements specific to the transmitter end
H04L 25/0292
Arrangements for coupling to transmission lines: arrangements specific to the receiver end

Family

Application08/772,175Parent of this continuation · filed 20 Dec 1996

Application09/418,790Parent of this continuation · filed 15 Oct 1999

US 2002/0186777 A1Pre-grant publication · published 12 Dec 2002

US 6,359,931 B1Parent of this continuation

Application09/418,790Parent of this continuation

US 6,005,895 AParent of this continuation

US 6,504,875 B2This patent

From the US filing history. Foreign family members aren’t listed.

Apparatus for multilevel signaling

Life of this patent

Apparatus for multilevel signaling

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims30

Description7,901 words

Drawings

Description7,901 words

Classification5 codes

Life of this patent