Altera Corporation

John Oh

Curt Wortman

Jean Luc Berube

Samson Tam

Jamshid Foroudian

Double data rate ('DDR') circuitry or the like is modified or enhanced to include edge detection capability. During edge detection mode the circuitry is supplied with serial training data that includes successive pairs of equal-valued bits. Several, differently-phased, candidate clock signals are used one after another in order of increasing phase to clock the DDR circuitry. Adjacent bits in the training data that should be equal-valued are captured by the DDR circuitry and compared. Any candidate clock signal that causes the bits thus compared to be unequal is flagged as having phase close to edges in the data. The approximate phase of data edges is thereby indicated by the phase (or phases) of the candidate clock signal (or signals) causing the bits compared as described above to be unequal.

Signal edge detection circuitry and methods

A multi-phase-locked loop (PLL) solution is described for multi-link multi-rate line cards. A reconfigurable enhanced phase-locked loop (EPLL) associated with a particular port in a line card is cascaded with an fast phase-locked loop (FPLL) and their combined output is used to provide a sampling clock to a data handler such as a serializer/deserializer (SERDES). The enhanced phase-locked loop (EPLL) is operable to take a multi-rate clock input and scale it accordingly to provide a fixed rate clock to the fast phase-locked loop (FPLL) input. The enhanced phase-locked loop (EPLL) can be dynamically reconfigured without affecting operation of other ports in the line card. The fast phase-locked loop (FPLL) and serializer/deserializer (SERDES) sample link data at a fixed rate and pass the data down through the communication system.

Growing community of inventors

San Jose, CA, United States of America

John Oh