Rapid sampling phase recovery
View Patent ↗In a communication receiver, timing recovery circuitry includes a loop filter associated with a timing recovery loop of a first communication device. The first communication device is in communication with a second communication device prior to a temporary power down/power up sequence in the first communication device. The loop filter is configured to: (i) temporarily disable at least a portion of the timing recovery loop after the temporary power down/power up sequence in the first communication device; and (ii) initiate a progression through a set of potential sampling phases to determine a given sampling phase at which the first communication device can recommence communication with the second communication device.
1. An apparatus comprising:
timing recovery circuitry comprising a loop filter associated with a timing recovery loop of a first communication device, the first communication device being in communication with a second communication device prior to a temporary power down/power up sequence in the first communication device;
wherein the loop filter is configured to: (i) temporarily disable at least a portion of the timing recovery loop after the temporary power down/power up sequence in the first communication device; and (ii) while the portion of the timing recovery loop is temporarily disabled, introduce a signal in a frequency recovery portion of the timing recovery loop operative to initiate a progression through a set of potential sampling phases to determine a given sampling phase at which the first communication device can recommence communication with the second communication device.
2. The apparatus of claim 1 , wherein the loop filter is further configured to re-enable the disabled portion of the timing recovery loop upon determination of the given sampling phase.
3. The apparatus of claim 1 , wherein the given sampling phase is determined in accordance with a metric indicative of a proximity to determining the given sampling phase.
4. The apparatus of claim 3 , wherein the metric comprises a performance metric.
5. The apparatus of claim 4 , wherein the performance metric comprises an establishment of a lock condition in a scrambler of the first communication device.
6. The apparatus of claim 4 , wherein the performance metric comprises a given mean square error at a slicer of the first communication device.
7. The apparatus of claim 4 , wherein the performance metric comprises a quality measure of an eye diagram associated with a slicer of the first communication device.
8. The apparatus of claim 1 , wherein the signal initiating the progression through the set of potential sampling phases has a given frequency offset value.
9. The apparatus of claim 8 , wherein the given frequency offset value is fixed.
10. The apparatus of claim 8 , wherein the given frequency offset value is variable.
11. The apparatus of claim 10 , wherein the given frequency offset value has a variable magnitude proportional to a metric associated with the first communication device.
12. The apparatus of claim 1 , wherein the loop filter comprises:
a first branch; and
a second branch;
wherein at least one of a portion of the first branch and a portion of the second branch is disabled, to allow introduction of the signal that initiates the progression through the set of potential sampling phases, until the given sampling phase is determined.
13. An integrated circuit comprising the timing recovery circuitry of claim 1 .
14. A method comprising:
temporarily disabling at least a portion of a timing recovery loop after a temporary power down/power up sequence in a first communication device, the first communication device being in communication with a second communication device prior to the temporary power down/power up sequence in the first communication device; and
while the portion of the timing recovery loop is temporarily disabled, introducing a signal in a frequency recovery portion of the timing recovery loop operative to initiate a progression through a set of potential sampling phases to determine a given sampling phase at which the first communication device can recommence communication with the second communication device.
15. The method of claim 14 , further comprising re-enabling the disabled portion of the timing recovery loop upon determination of the given sampling phase.
16. The method of claim 14 , wherein the given sampling phase is determined in accordance with a metric indicative of a proximity to determining the given sampling phase.
17. The method of claim 16 , wherein the metric comprises a performance metric.
18. The method of claim 14 , wherein the signal initiating the progression through the set of potential sampling phases has a given frequency offset value.
19. The method of claim 14 , wherein the temporary power down/power up sequence is in accordance with an Energy-Efficient Ethernet standard.
20. A method of recovering an optimal sampling phase in a receiver after a power down/power up sequence, comprising:
disabling a sampling phase recovery portion of a timing recovery loop of the receiver;
introducing a frequency offset in a frequency recovery portion of the timing recovery loop such that the timing recovery loop progresses through a set of potential sampling phases;
as progression through the set of potential sampling phases proceeds, using a metric to determine how close the timing recovery loop is to the optimal sampling phase; and
when it is determined that the timing recovery loop is suitably close to the optimal sampling phase, removing the frequency offset and re-enabling the phase recovery portion of the timing recovery loop.