Multilane SERDES clock and data skew alignment for multi-standard support
A communication system may include a number of communication channels operating in accordance with one or more communication standards. The channels may generate data clocks from one or more master clock signals. The phase of the data clocks may be aligned using phase detectors for determining respective phase relationships and using phase interpolators for adjusting respective clock phases. The communication system may include communication channels that operate at different data clock frequencies. These systems may divide their respective data clocks in order to achieve a common clock frequency for use in their phase alignment. The phase detectors and associated circuitry may be disabled to save power when not in use.
1. A communication system, comprising:
a first communication channel that includes
a first divider configured to generate a first divided clock signal based on a master clock signal, the first divided clock signal configured to clock a first data stream through the first communication channel; and
a second communication channel that includes
a phase interpolator configured to receive the master clock signal and generate a first phase adjusted clock signal,
a second divider configured to generate a second divided clock signal from the first phase adjusted clock signal, the second divided clock signal configured to clock a second data stream through the second communication channel, and
a phase detector configured to determine a phase difference between the first divided clock signal and the second divided clock signal;
wherein the phase interpolator is configured to adjust a phase of the first phase adjusted clock signal based on the determined phase difference.
2. The communication system of claim 1 , further comprising:
at least one additional communication channel that includes
a corresponding phase interpolator configured to receive the master clock signal and generate a corresponding phase adjusted clock signal,
a corresponding divider configured to generate a corresponding divided clock signal from the corresponding phase adjusted clock signal, the corresponding divided clock signal configured to clock a corresponding data stream through the corresponding communication channel, and
a corresponding phase detector configured to determine a phase difference between the first divided clock signal and the corresponding divided clock signal;
wherein the corresponding phase interpolator is configured to adjust a phase of the corresponding phase adjusted clock signal based on the determined phase difference between the first divided clock signal and the corresponding divided clock signal.
3. The communication system of claim 1 , further comprising:
a third communication channel that includes
a second phase interpolator configured to receive the master clock signal and generate a second phase adjusted clock signal,
a third divider configured to generate a third divided clock signal from the second phase adjusted clock signal, the third divided clock signal configured to clock a third data stream through the third communication channel, and
a second phase detector configured to determine a phase difference between the first divided clock signal and the third divided clock signal;
wherein the second phase interpolator is configured to adjust a phase of the second phase adjusted clock signal based on the determined phase difference between the second divided clock signal and the third divided clock signal.
4. The communication system of claim 1 , wherein the communication system includes a plurality of communication channels that includes the first and second communication channels;
wherein in a first implementation of the plurality of communication channels, at least a first subset of the plurality of communication channels are configured to transmit a first plurality of data streams according to a first communication standard; and
wherein in a second implementation of the plurality of communication channels, at least a second subset of the plurality of communication channels are configured to transmit a second plurality of data streams according to a second communication standard, the first communication standard being different from the second communication standard.
5. The communication system of claim 4 , wherein the first implementation and the second implementation are simultaneously present in the communication system; and
wherein the communication system is configured to transmit the first plurality of data streams and the second plurality of data streams in at least one of a synchronous manner or an asynchronous manner with respect to each other.
6. The communication system of claim 1 , wherein the phase detector comprises a flip flop configured to receive the first divided clock signal at a clock input and configured to receive the second divided clock signal at a data input.
7. The communication system of claim 1 , further comprising a digital circuit portion configured to receive a signal indicative of the determined phase difference from the phase detector and configured to transmit a phase adjustment signal to the phase interpolator based at least in part on the received signal indicative of the determined phase difference.
8. The communication system of claim 7 , wherein the signal indicative of the determined phase difference comprises at least one of a value associated with a leading phase or a value associated with a lagging phase; and
wherein the digital circuit portion is further configured to transmit the phase adjustment signal based at least in part on a predetermined number of samples of the signal indicative of the determined phase difference having the same value of a period of time.
9. The communication system of claim 1 , further comprising at least one of:
the phase detector being configured to be disabled in response to completing the adjustment of the first phase adjusted clock signal, or
at least one physical connection made to one or more of the phase detector, the phase interpolator, the first divider, or the second divider is a balanced routing connection configured to reduce signal delay or to reduce a skew mismatch.
10. The communication system of claim 1 , further comprising:
an additional communication channel that includes
an additional phase interpolator configured to receive the master clock signal and generate an additional phase adjusted clock signal, and
an additional divider configured to generate an additional divided clock signal from the second phase adjusted clock signal, the additional divided clock signal configured to clock an additional data stream through the additional communication channel; and
a selector configured to select, as a selector input, at least one of the additional divided clock signal or the second divided clock signal, the selector further configured to output the selector input to the phase detector;
wherein the additional phase interpolator is configured to adjust a phase of the additional phase adjusted clock signal based on an additionally determined phase difference between the additional phase adjusted clock signal and the first divided clock signal, the additionally determined phase difference being determined by the phase detector.
11. A communication system, comprising:
a first communication channel that includes
a first phase interpolator configured to receive a first master clock signal and generates a first phase adjusted clock signal,
a first divider configured to divide the first phase adjusted clock signal by a first factor to generate a first divided clock signal, the first divided clock signal configured to clock a first data stream through the first communication channel, and
a second divider configured to divide the first divided clock signal to generate a second divided clock signal;
a second communication channel that includes
a second phase interpolator configured to receive a second master clock signal and generate a second phase adjusted clock signal,
a third divider configured to divide the second phase adjusted clock signal by a second factor that is different than the first factor to generate a third divided clock signal, the third divided clock signal configured to clock a second data stream through the second communication channel, and
a fourth divider configured to divide the third divided clock signal to generate a fourth divided clock signal of a same frequency as the second divided clock signal; and
a phase detector configured to determine a phase difference between the second divided clock signal and the fourth divided clock signal;
wherein a phase of the second phase adjusted clock signal is adjusted by the second phase interpolator based on the determined phase difference.
12. The communication system of claim 11 , wherein the phase detector comprises a flip flop configured to receive the second divided clock signal at a clock input and configured to receive the fourth divided clock signal at a data input.
13. The communication system of claim 11 , further comprising a digital circuit portion configured to receive a signal indicative of the determined phase difference from the phase detector and configured to transmit a phase adjustment signal to the second phase interpolator based at least in part on the received signal indicative of the determined phase difference.
14. The communication system of claim 11 , further comprising a time-delay element configured to delay at least one of the first data stream or the second data stream.
15. The communication system of claim 11 , wherein the phase detector is configured to be disabled in response to completing the adjustment of the second phase adjusted clock signal.
16. The communication system of claim 12 , wherein the first communication channel is configured to transmit at least one data stream according to a first communication standard, and wherein the second communication channel is configured to transmit at least one other data stream according to a second communication standard.
17. A method, comprising:
generating a first phase adjusted clock signal for a first communication channel based on a master clock signal;
generating a first divided clock signal based on the first phase adjusted clock signal;
generating a second phase adjusted clock signal for a second communication channel based on the master clock signal;
generating a second divided clock signal based on the second phase adjusted clock signal;
determining a first phase difference between the first divided clock signal and the second divided clock signal; and
adjusting a phase of the second phase adjusted clock signal based on the first determined phase difference.
18. The method of claim 17 , further comprising
transmitting data on the first communication channel based on the first divided clock according to a first communication protocol; and
transmitting data on the second communication channel based on the second divided clock according to a second communication protocol.
19. The method of claim 17 , further comprising:
generating a third phase adjusted clock signal for a third communication channel;
generating a third divided clock signal based on the third phase adjusted clock signal;
determining a second phase difference between the first divided clock signal and the third divided clock signal; and
adjusting a phase of the third phase adjusted clock signal based on the second determined phase difference.
20. The method of claim 17 , further comprising:
generating a third phase adjusted clock signal for a third communication channel;
generating a third divided clock signal based on the third phase adjusted clock signal;
determining a second phase difference between the second divided clock signal and the third divided clock signal; and
adjusting a phase of the third phase adjusted clock signal based on the second determined phase difference.