Interfacing between integrated circuits with asymmetric voltage swing

1. An apparatus comprising:

a first integrated circuit including a first transmitter and a first receiver;

a second integrated circuit including a second transmitter and a second receiver; and

an interface including communication channel linking the first transmitter with the second receiver and the first receiver with the second transmitter, wherein the communication channel is one of a single channel or a dual channel;

wherein the first transmitter is operable to transmit a first signal and the second transmitter is operable to transmit a second signal, a first average voltage swing of the first signal being asymmetric with a second average voltage swing of the second signal.

2. The apparatus of claim 1 , wherein the first transmitter is one of a single-ended transmitter or a differential transmitter.

3. The apparatus of claim 1 , wherein the first transmitter output is referenced either to low supply wherein a signal reference is to ground, to high supply wherein a signal reference is to a supply voltage, or to a combination of both low supply and high supply.

4. The apparatus of claim 1 , wherein an output of the first transmitter includes non-return to zero (NRZ) coding.

5. The apparatus of claim 1 , wherein one of the first transmitter's outputs is substantially equal to a supply voltage of one or more supply voltages supplied to the transmitter.

6. The apparatus of claim 1 , wherein the first integrated circuit includes a memory controller and wherein the second integrated circuit includes a memory.

7. The apparatus of claim 6 , wherein the memory is a dynamic random access memory (DRAM).

8. The apparatus of claim 6 , wherein the memory controller is a system on chip (SoC).

9. The apparatus of claim 1 , wherein the first receiver of the first integrated circuit has greater signal sensitivity than the second receiver of the second integrated circuit.

10. The apparatus of claim 1 , where a supply voltage of the first integrated circuit is smaller than a supply voltage of the second integrated circuit.

11. A method comprising:

establishing a first voltage swing for transmission from a first integrated circuit, the first integrated circuit including a first transmitter and a first receiver, to a second integrated circuit, the second integrated circuit including a second transmitter and a second receiver;

establishing a second voltage swing for transmission from the second integrated circuit to the first integrated circuit;

transmitting a first signal from the first transmitter to the second receiver using the first voltage swing; and

transmitting a second signal from the second transmitter to the first receiver using the second voltage swing;

wherein the first voltage swing and the second voltage swing are asymmetric.

12. The method of claim 11 , wherein the first integrated circuit includes a memory controller and wherein the second integrated circuit includes a memory.

13. The method of claim 11 , wherein:

establishing the first voltage swing includes establishing a signal swing that is sufficient to meet specifications of the second integrated circuit after attenuation by a communication channel between the first transmitter and the second receiver; and

establishing the second voltage swing includes establishing a signal swing that is sufficient to meet specifications of the first integrated circuit after attenuation by a communication channel between the second transmitter and the first receiver.

14. The method of claim 13 , wherein the communication channel between the first transmitter and the second receiver is a first channel of a dual communication channel and the communication channel between the second transmitter and the first receiver is a second channel of the dual communication channel.

15. The method of claim 13 , wherein the communication channel between the first transmitter and the second receiver is the same as the communication channel between the second transmitter and the first receiver.

16. The method of claim 13 , wherein the first receiver has greater signal sensitivity than the second receiver.

17. A system comprising:

a processing element for processing data;

a memory controller including a first transmitter and a first receiver;

a DRAM (dynamic random access memory) for storage of data, the DRAM including a second transmitter and a second receiver; and

an interface between the memory controller and the DRAM including a communication channel linking the first transmitter with the second receiver and the first receiver with the second transmitter;

wherein the first transmitter is operable to transmit a first signal and the second transmitter is operable to transmit a second signal, a first average voltage swing of the first signal being asymmetric with a second average voltage swing of the second signal.

18. The system of claim 17 , wherein the memory controller is a system on chip (SoC).

19. The system of claim 17 , wherein the first receiver of the controller has greater signal sensitivity than the second receiver of the DRAM.

20. A computer-readable storage medium having stored thereon data representing sequences of instructions that, when executed by a processor, cause the processor to perform operations comprising:

establishing a first voltage swing for transmission from a memory controller, the first memory controller including a first transmitter and a first receiver, to a memory, the memory including a second transmitter and a second receiver, via an I/O (input/output) interface;

establishing a second voltage swing for transmission from the memory to the memory controller;

transmitting a first signal from the first transmitter to the second receiver using the first voltage swing; and

transmitting a second signal from the second transmitter to the first receiver using the second voltage swing;

wherein the first voltage swing of the memory controller and the second voltage swing of the memory are asymmetric with each other.

21. The medium of claim 20 , wherein:

establishing the first voltage swing includes establishing a signal swing that is sufficient to meet specifications of the memory after attenuation by a communication channel between the first transmitter and the second receiver; and

establishing the second voltage swing includes establishing a signal swing that is sufficient to meet specifications of the memory controller after attenuation by a communication channel between the second transmitter and the first receiver.

22. The medium of claim 21 , wherein the communication channel between the first transmitter and the second receiver is a first channel of a dual communication channel and the communication channel between the second transmitter and the first receiver is a second channel of the dual communication channel.

23. The medium of claim 21 , wherein the communication channel between the first transmitter and the second receiver is the same as the communication channel between the second transmitter and the first receiver.

24. The medium of claim 21 , wherein the controller is a device with faster performance and more sensitivity than the memory and can tolerate lower signal voltages in comparison with the memory.