Oscillators’ Jitter Specs Are Low Or Super-Low

A pair of high-end, 155.52-MHz clock oscillators for datacomm applications have virtually identical specifications except for their jitter. Model M18407 applies ECLPS logic to achieve maximum jitter of 5 ps rms, while the M18405 achieves 10-ps rms jitter using slower ECL10K logic.Both units achieve frequencies to 155.52 MHz by resonating AT-cut crystals at the fifth harmonic of their natural frequency. The overtone technique solves the problems related to the excessive fragility of crystals thin enough to resonate in fundamental mode at such high frequencies.Both operate from -5 vdc ±5% supplies and draw 45 mA at -5V and 60 mA maximum at -5.5V. Waveform symmetry is typically 45/55 and 40/60 worst case. Frequency stability over the zero to 70°C range is better than 20 ppm.