Oscillators for timing purposes should maintain their frequency over time, temperature, and various changing environmental conditions. The G326 series of voltage-controlled crystal oscillators (VCXOs) from Saelig Company Inc. ranges in frequency from 1 to 50 MHz with outstanding timing consistency, measured in terms of integrated phase jitter of typically only 200 fs. These miniature crystal oscillators are suitable for use in phase-locked loops (PLLs) and applications that depend on precise timing, including SONET systems and wireless-communications equipment.
The G326 series of oscillators differ from conventional fixed-frequency crystal oscillators since they can be tuned by 50 to 200 ppm in frequency for applications requiring dynamic changes to system clock frequency. The frequency is tuned by varying a control voltage feeding a varactor tuning diode within the crystal-oscillator package. The VCXOs come in a miniature six-pad surface-mount-device (SMD) package measuring just 3.2 × 2.5 × 1.0 mm. They are available in numerous versions for use with different supply voltages, including +1.8, +2.5, +3.3, and +5.0 V dc, and with CMOS or two-gate transistor-transistor-logic (TTL) oscillator outputs.
The clock oscillators achieve rise/fall times of 6 ns or better with startup time of 10 ms and current consumption of 10 to 45 mA, depending on frequency. They are designed for 50 ± 10% duty cycle (with ±5% tolerance available to order) and provide linearity of 10% or better, and typically 5%. The G326 series, manufactured by quartz-crystal specialist Euroquartz, handle commercial operating temperatures from –10 to +70°C and industrial operating temperatures from –40 to +85°C.