Using General-Purpose PLLs with APEX II Devices

    APEXTM II devices have ClockLockTM, ClockBoostTM, and ClockShiftTM features that use general-purpose phase-locked loops (PLLs) to increase performance and provide clock-frequency synthesis. The ClockLock feature minimizes clock delay and clock skew within the device, reducing clock-to-output and setup times while maintaining zero hold times. APEX II devices also include advanced ClockBoost circuitry for fractional or integer multiplication. Designers can use ClockBoost circuitry to run the internal logic of the device at a faster or slower rate than the input clock frequency. The ClockShift circuitry allows complex clock phase- and delay-shifting applications. APEX II general-purpose PLLs also generate external clock outputs with feedback ability. These enhanced features permit system-level clock management and skew control in APEX II devices.