Abstract: A system and method for synchronizing clocks across a packet-switched network eliminates wander accumulation to enable precision clock distribution across a large network. In addition to standard Precision Time Protocol (PTP) synchronization messages or similar time synchronization messages, each clock regenerator stage receives a grand clock error message from the previous stage, updates this error message with its own stage clock error, and then transmits the updated grand clock error to the next stage. This enables the synchronization algorithm to compensate for the error of the previous stage, effectively locking each clock regenerator stage to the grand master clock directly.
Abstract: A single-wire serial communications bus has a master device and one or more slave devices. The slave devices are addressed according to a predetermined addressing scheme in an address space. The master device starts a transmission with a number of line state changes which define a clock period to be used by the slave devices in clocking and framing the serial data. This permits omitting a clock line, thus saving a pin and saving printed circuit board space. This also permits the slave devices to shut down their own clocks during periods of inactivity on the bus, thus saving power. Likewise the master device is able to shut down its clock during periods of bus inactivity.
Type:
Grant
Filed:
April 28, 2003
Date of Patent:
April 14, 2009
Assignee:
Semtech Corp.
Inventors:
Carl Hejdeman, Victor Marten, Andrew McKnight
Abstract: A phase detection system allows the capture range, lock range and jitter tolerance to be extended beyond ±360°. The capture range for the phase detection system may be extended in programmable amounts up to several thousand clock cycles or can be set to any desired maximum capture range in steps of approximately 360°. The phase detection system circuit utilizes a coarse phase detector and a fine phase detector. The phase detection system uses the digital cycle slip counter phase detector to provide a wide phase capture and lock range for a large jitter tolerance. The phase detection system combines this detector with a fine phase measurement from a PFD (phase and frequency detector) for very accurate phase control and low output jitter. The PFD operates in the approximately ±540° range and provides overlap in response with a coarse phase detector using a digital cycle counter approach.