Deskew in a high speed link
View Patent ↗Systems and methods for high speed communications are described herein. In certain aspects, the systems and methods include innovative transceiver architectures and techniques for re-timing, multiplexing, de-multiplexing and transmitting data. The systems and methods can be used to achieve reliable high-speed point-to-point communication between different electronic devices, computing devices, storage devices and peripheral devices.
1. A transceiver integrated circuit (IC) for a communication system, wherein the transceiver IC comprises:
a differential transmitter configured to generate a differential signal for transmission via an external cable, wherein the differential transmitter comprises:
a first transmitter configured to generate a non-inverted component of the differential signal, wherein the first transmitter is configured to receive a first data signal and a first clock signal that controls timing of transmissions of the first transmitter; and
a second transmitter configured to generate an inverted component of the differential signal, wherein the second transmitter is configured to receive a second data signal and a second clock signal that controls timing of transmissions of the second transmitter; and
a skew adjustment circuit configured to provide a first amount of skew adjustment to the differential transmitter by adjusting a relative delay between the first data signal and the second data signal, and to provide a second amount of skew adjustment to the differential transmitter by adjusting a relative delay between the first clock signal and the second clock signal.
2. The transceiver IC of claim 1 , wherein the first transmitter comprises a first digital-to-analog converter (DAC) configured to generate the non-inverted component of the differential signal based on converting the first data signal, and the second transmitter comprises a second DAC configured to generate the inverted component of the differential signal based on converting the second data signal.
3. The transceiver IC of claim 1 , wherein the first amount of skew adjustment comprises a coarse adjustment and the second amount of skew adjustment comprises a fine adjustment having a finer resolution than the coarse adjustment, wherein the skew adjustment circuit is configured to provide the second amount of skew adjustment after the first amount of skew adjustment.
4. The transceiver IC of claim 1 , wherein the transceiver IC further comprises a skew control circuit configured to receive a skew indication signal indicating a skew of the differential signal, and to control at least one of the first amount of skew adjustment and the second amount of skew adjustment provided by the skew adjustment circuit based on the skew indication signal.
5. The transceiver IC of claim 4 , wherein the skew control circuit is further configured to incrementally control the at least one of the first amount of skew adjustment and the second amount of skew adjustment until the skew indication signal indicates that a direction of the skew has reversed.
6. The transceiver IC of claim 1 , wherein the skew adjustment circuit comprises a clock generation unit configured to generate at least one clock signal having a clock cycle, and a first phase selection circuit configured to provide the first amount of skew adjustment by providing phase adjustment in full increments of the clock cycle.
7. The transceiver IC of claim 6 , wherein the skew adjustment circuit further comprises a second phase selection circuit configured to provide the second amount of skew adjustment by providing phase adjustment in increments of less than the clock cycle.
8. A communication system comprising:
a cable; and
a first integrated circuit (IC) comprising:
a differential transmitter configured to transmit a differential signal over the cable, wherein the differential transmitter comprises a first transmitter configured to generate a non-inverted component of the differential signal and a second transmitter configured to generate an inverted component of the differential signal, wherein the first transmitter is configured to receive a first data signal and a first clock signal that controls timing of transmissions of the first transmitter, and wherein the second transmitter is configured to receive a second data signal and a second clock signal that controls timing of transmissions of the second transmitter; and
a skew adjustment circuit configured to provide a first amount of skew adjustment to the differential transmitter by adjusting a relative delay between the first data signal and the second data signal, and to provide a second amount of skew adjustment to the differential transmitter by adjusting a relative delay between the first clock signal and the second clock signal.
9. The communication system of claim 8 , further comprising a second IC comprising a differential receiver configured to receive the differential signal from the cable.
10. The communication system of claim 9 , wherein the second IC further comprises a skew detector configured to generate a skew indication signal indicating a skew between the non-inverted component and the inverted component of the differential signal, and a skew transmitter configured to transmit the skew indication signal to the first IC.
11. The communication system of claim 10 , wherein the cable comprises a pair of micro coaxial lines configured to carry the differential signal and a control line configured to carry the skew indication signal.
12. The communication system of claim 8 , wherein the first transmitter comprises a first digital-to-analog converter (DAC) configured to generate the non-inverted component of the differential signal based on converting the first data signal, and the second transmitter comprises a second DAC configured to generate the inverted component of the differential signal based on converting the second data signal.
13. The communication system of claim 8 , wherein the first amount of skew adjustment comprises a coarse adjustment and the second amount of skew adjustment comprises a fine adjustment having a finer resolution than the coarse adjustment, wherein the skew adjustment circuit is configured to provide the second amount of skew adjustment after the first amount of skew adjustment.
14. The communication system of claim 8 , wherein the first IC further comprises a skew control circuit configured to receive a skew indication signal indicating a skew of the differential signal, and to control at least one of the first amount of skew adjustment and the second amount of skew adjustment provided by the skew adjustment circuit based on the skew indication signal.
15. The communication system of claim 14 , wherein the skew control circuit is further configured to incrementally control at at least one of the first amount of skew adjustment and the second amount of skew adjustment until the skew indication signal indicates that a direction of the skew has reversed.
16. The communication system of claim 8 , wherein the skew adjustment circuit comprises a clock generation unit configured to generate at least one clock signal having a clock cycle, and a first phase selection circuit configured to provide the first amount of skew adjustment by providing phase adjustment in full increments of the clock cycle.
17. The communication system of claim 16 , wherein the skew adjustment circuit further comprises a second phase selection circuit configured to provide the second amount of skew adjustment by providing phase adjustment in increments of less than the clock cycle.
18. A method of skew correction in a communication system, the method comprising:
transmitting a non-inverted component of a differential signal over a cable using a first transmitter of a differential transmitter;
transmitting an inverted component of the differential signal over the cable using a second transmitter of the differential transmitter;
providing a first amount of skew adjustment to the differential transmitter by adjusting a relative delay between a first data signal inputted to the first transmitter and a second data signal inputted to the second transmitter; and
providing a second amount of skew adjustment to the differential transmitter by adjusting a relative delay between a first clock signal for timing transmissions of the first transmitter and a second clock signal for timing transmissions of the second transmitter,
wherein the first clock signal is inputted to the first transmitter and the second clock signal is inputted to the second transmitter.
19. The method of claim 18 , further comprising receiving the differential signal at a differential receiver via the cable, observing a skew of the differential signal using a skew detector of the differential receiver, and controlling the first amount of skew adjustment and the second amount of skew adjustment based on the observed skew.
20. The method of claim 18 , further comprising providing the second amount of skew adjustment after the first amount of skew adjustment, wherein the first amount of skew adjustment comprises a coarse adjustment and the second amount of skew adjustment comprises a fine adjustment having a finer resolution than the coarse adjustment.