Electronic Design

3.3-V Oscillator Generates Low-Jitter Output To 410 MHz

The M2984 is being introduced as the first 3.3-V oscillator to achieve 150- to 410-MHz output. It relies on an inverted-mesa crystal design, third-overtone operation, and PECL logic to reach such high-frequency operation, while maintaining low jitter—10-ps rms max and 5-ps typical.

Jitter is a critical specification in many datacom applications, and 10-ps performance is now considered to be a virtual standard rather than a goal. Adding to this challenge is the need for 3.3-V operation, as designers of datacom and telecom equipment migrate their designs from 5 to 3.3 V to take advantage of the lower-voltage chips now available.

The M2984 provides dual complementary PECL outputs for differential clock-signal transmission, which enhances immunity to RFI and minimizes waveform distortion. Typical waveform rise and fall times are 225 ps. Frequency stability is better than 20 ppm from 0° to 70°C, including supply, load, and aging variations. Drift is ±3 ppm in the first year, followed subsequently by a drift of ±1 ppm per year. The oscillator consumes 60-mA max at 3.3 V, and supply-voltage tolerance is ±5%.

The M2984 will oscillate regardless of how the supply voltage is applied. It starts up within 5 ms of the dc supply voltage reaching the rated level. Additionally, built-in 0.1-µF bypass capacitors minimize the effects of supply-voltage transients.

Units are housed in 0.8- by 0.5- by 0.2-in. DIL through-hole stainless-steel packages. In production quantities, the oscillator is priced at $25.50 to $29.50, with a delivery of stock to approximately six weeks.

MF Electronics Corp., 10 Commerce Dr., New Rochelle, NY 10801; Will Finkelstein, (800) 331-1236; fax (914) 576-6204; e-mail: [email protected]; Internet: www.mfelectronics.com.

See associated figure.

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