Jitter-attenuating clock translator cuts power in communications systems
An embedded cross-point switch at its input provides greater flexibility and lower cost of ownership than maintaining different clocking configurations of multiple parts. The AD9554 dissipates only 940 mW while generating up to eight output clocks over an output range of 430 kHz to 941 MHz, synchronised to four 2-kHz to 1-GHz external input references, with a loop bandwidth as low as 0.1 Hz. The four analogue-digital phase-locked loops (ADPLLs) enable the reduction of input jitter or phase noise associated with the external references. The digitally controlled loop and holdover circuitry of the AD9554 continuously generates a low jitter output clock even when all reference inputs have failed. The AD9554 has adaptive clocking capability that allows the user to dynamically change the DPLL divide ratios while they are locked.
The AD9554 clock’s high level of integration, adaptive clocking capability, and optical transport network (OTN) mapping algorithm embedded in DPLL reduces system costs by simplifying clocking circuitry and eliminating software control routines. Output jitter is 250 fsec over the 50-kHz to 80-MHz range and 350 fsec over the 12-kHz to 20-MHz range.
Features include:
GR-1244 Stratum 3 stability in holdover mode
Smooth reference switchover with virtually no disturbance on output phase
Adaptive clocking allows dynamic adjustment of feedback dividers in OTN mapping/demapping
Quad ADPLL architecture:
Four reference inputs (single-ended or differential)
Eight outputs (single-ended or differential)
4×4 crosspoint allows any reference input to drive any output
Supports ITU-T G.823, ITU-T G.824, ITU-T G.825, and ITU-T G.8261, and ITU-T G.8262
Loop bandwidth as low as 0.1Hz to guarantee SyncE compliance
In a 72-lead LFCSP the part costs $21.33 (1000).
Analog Devices; www.analog.com/AD9554
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