Apparatus and method for multilevel signaling
AssigneeRambus Inc.
InventorsDonald V. Perino, John B. Dillon
Life of this patent
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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.
Claims17
A signaling apparatus 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 either the first terminal or second terminal 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 either the first terminal or second terminal 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 either the first terminal or second terminal 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 either the first terminal or second terminal of the fourth switch, and
- a plurality of conductors including:
- a first conductor having a first end connected to the first terminal of the first switch and the second terminal of the second switch;
- a second conductor having a first end connected to the first terminal of the second switch and the second terminal of the third switch;
- a third conductor having a first end connected to the first terminal of the third switch and the second terminal of the fourth switch;
- and
- a fourth conductor having a first end connected to the first terminal of the fourth switch and the second terminal of the first switch.
A receiver circuit for receiving multi-level signals, the receiver circuit comprises:
- a first comparator having a first input and a second input wherein the first input is coupled to a first terminal and the second input is coupled to a second terminal;
- a second comparator having a first input and a second input wherein the first input is coupled to the second terminal and the second input is coupled to a third terminal;
- a third comparator having a first input and a second input wherein the first input is coupled to the third terminal and the second input is coupled to a fourth terminal;
- a fourth comparator having a first input and a second input wherein the first input is coupled to the fourth terminal and the second input is coupled to the first terminal;
- a fifth comparator having a first input and a second input wherein the first input is coupled to the fourth terminal and the second input is coupled to the second terminal;
- and
- a sixth comparator having a first input and a second input wherein the first input is coupled to the third terminal and the second input is coupled to the first terminal.
Dependencies are inferred from the claim text.