Oscillator Delivers Super-Fast Clocks With Low Jitter

The ever-widening bandwidth of datacomm and other systems is creating a demand for low-jitter clock generators that can operate at higher and higher frequencies. One of the latest devices claiming to meet the required specs is a line of 3.3V oscillators that spans a 150-to-410-MHz frequency range. Employing an inverted mesa crystal and PECL logic, Model M2984 clock oscillator operates at 250 MHz and offers a guaranteed maximum jitter of 10 ps_RMS (5 ps typ.)--inverted mesa crystals are quartz crystals with a well etched into them to overcome their frequency-generating limitations.The oscillator draws 60 mA at 3.3V, with the fast PECL logic providing dual complementary outputs, 45/55 waveform symmetry, and preservation of the crystal’s inherently low jitter. Rise/fall time of the output waveform is 225 ps. Frequency stability over a 0°C to 70°C range is better than 20 ppm, including variations in dc supply, load and aging. The unit is designed to ensure that oscillation will take place regardless of how the supply voltage is applied (e.g., gradual ramp up, sudden-on, etc.). M2984 comes in a standard stainless steel DIL package measuring 0.8" x 0.5" x 0.2".