Cavium, Inc.

Marvell International Limited

Mark Spaeth

Scott E Meninger

Ethan Crain

A clock and data recovery (CDR) circuit operates to recover a clock and sample data from full-rate and sub-rate data signals. The CDR circuit selectively shifts one or more of the sampling clocks based on the rate of a received data signal, facilitating accurate sampling of sub-rate data signals. A masking circuit selectively masks data output bits clocked by a selection of the sampling clocks, thereby outputting relevant sampled data.

Clock and data recovery of sub-rate data

Modular serializer and deserializer circuits convert a data input in a variety of applications. The serializer includes an array of cells that receive a parallel data input and transfer the word, row by row, to an output buffer that generates a corresponding serial data output. The deserializer includes an input buffer that receives a serial data input and transfers partial words sequentially through an array of cells. When the word fully occupies the cells, the array transmits the word as a parallel data output. A modular clock operates to clock the modular serializer and deserializer.

Modular serializer and deserializer

A programmable current driver provides de-emphasis capability. A number of identical transmitter slices, consisting of a unit current source and a unit differential pair, are connected in parallel to the termination resistors. As the transmitter slices are identical, the current density through the differential pairs are identical, and the VDS voltages across them (as well as the VDS voltages across the unit current sources) are the same, ensuring that the current through each slice is identical (within the limits of device matching). Biasing circuitry ensures that each unit current source sinks a current having a fixed proportion to the total current.

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Marlborough, MA, United States of America

Mark Spaeth