Coherent Logix, Inc.

Christopher L Schreppel

Carl S Dobbs

Michael R Trocino

Kenneth R Faulkner

Embodiments of a synchronous digital system are disclosed that may include generation of clock and synchronization signals. Any of a plurality of available clock signals may be selected for use as a primary clock, without causing clock-induced errors in the synchronous digital system. A clock signal generated on-chip with the synchronous digital system may be automatically selected in response to detecting a condition indicating that use of a local clock may be necessary. Such conditions may include detection of tampering with the synchronous digital system. If an indication of tampering is detected, security measures may be performed.

Clock distribution network for multi-frequency multi-processor systems

Embodiments of a synchronous digital system are disclosed that may include generation of clock and synchronization signals. Any of a plurality of available clock signals may be selected for use as a primary clock, without causing clock-induced errors in the synchronous digital system. The clock signals may be selected automatically or programmatically. Clock generation circuitry may generate a clock signal that is initially used as the primary clock. The clock generation circuitry may be dynamically reconfigured without interrupting operation of the synchronous digital system, by first selecting another of the available clock signals for use as the primary clock.

Automatic selection of on-chip clock in synchronous digital systems

Embodiments are disclosed of an apparatus capable of performing multi-rate synchronous communication between component chips. Each chip may receive a common clock reference signal, and may generate an internal clock signal dependent on the clock reference signal. A clock distribution tree and phase-locked loop may be used to minimize internal clock skew at I/O circuitry at the chip perimeter. Each chip may also generate an internal synchronizing signal that is phase-aligned to the received clock reference signal. Each chip may use its respective synchronizing signal to synchronize multiple clock dividers that provide software-selectable adjusted-frequency clock signals to the I/O cells of the chip. In this way, the adjusted-frequency clock signals of the multiple chips are edge-aligned to the low-skew internal clock signals, and phase-aligned to the common clock reference signal, allowing the I/O cells of the multiple chips to perform synchronous communication at multiple rates with low clock skew.

Multi-frequency clock skew control for inter-chip communication in synchronous digital systems

Embodiments are disclosed of a multi-chip apparatus capable of performing multi-rate synchronous communication between component chips. Each chip may receive a common clock reference signal, and may generate an internal clock signal dependent on the clock reference signal. A clock distribution tree and phase-locked loop may be used to minimize internal clock skew at I/O circuitry at the chip perimeter. Each chip may also generate an internal synchronizing signal that is phase-aligned to the received clock reference signal. Each chip may use its respective synchronizing signal to synchronize multiple clock dividers that provide software-selectable reduced-frequency clock signals to the I/O cells of the chip. In this way, the reduced-frequency clock signals of the multiple chips are edge-aligned to the low-skew internal clock signals, and phase-aligned to the common clock reference signal, allowing the I/O cells of the multiple chips to perform synchronous communication at multiple rates with low clock skew.

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Austin, TX, United States of America

Christopher L Schreppel