Satellite NASA

Low-Power OCXOs Take Flight in LEOS Systems

These oven-controlled crystal oscillators provide stable output signals with low phase noise and power consumption and high radiation tolerance for satellite applications.

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Running out of power in a satellite can be costly, since changing batteries is no simple matter. Fortunately, advances made by Bliley Technologies on its Iris line of oven-controlled crystal oscillators (OCXOs) have instilled the traditional stability of OCXOs without the traditionally high power consumption.

Available with sinewave or HCMOS-level outputs, the product family includes high radiation tolerance, low phase noise, and excellent acceleration sensitivity with output frequencies reaching 100 MHz. The Iris OCXOs are designed for long running times in low-Earth-orbit satellites (LEOS) or any application where power consumption is a concern, including unmanned aerial vehicles (UAVs).

One example of a LEOS master reference oscillator available in the Iris line is model NV45AY (see figure), a 100-MHz sinewave Iris OCXO designed to handle the radiation exposure typical of LEOS, both total ionizing dosage (TID) and linear energy transfer (LET). It is radiation-tolerant to 40 krad TID and 40 MeV LET. For space use, it also boasts 0.3 ppb/g acceleration sensitivity. Model NV45AY provides +10 dBm typical output power at 100 MHz with 1.5-W typical steady-state power consumption from a +5-V dc supply. Power consumption at startup is only 2.5 W, with a maximum warmup time of about 3 min.

The Iris line of OCXOs, which comes in compact surface-mount housings with low power consumption, includes the 100-MHz model NV45AY with high radiation tolerance for LEOS applications.

The NV45AY OCXO is well-suited for battery-powered electronic devices, such as commercial and military portable radios, and even in guidance/navigation devices that require accurate timing but Global Positioning System (GPS) coverage may not be available. Maximum harmonic and spurious levels into a 50-Ω load are ‒30 and ‒80 dBc, respectively. Room-temperature (+25ºC) phase noise for the model NV45AY is quite impressive, with worst-case values at ‒95 dBc/Hz offset 10 Hz from the carrier, ‒125 dBc/Hz offset 100 Hz, ‒155 dBc/Hz offset 1 kHz, ‒168 dBc/Hz offset 10 kHz from the carrier, and ‒168 dBc/Hz offset 100 kHz from the carrier.

All members of the Iris line come in surface-mount-technology (SMT) housings measuring 0.5 × 0.5 in. They can be designed for supply voltages of +3.3 V dc ±5% or +5.0 V dc ±5%.

The oscillators are available with various grades of frequency-versus-temperature performance: ±25, 50, 75, or 100 ppb from ‒20 to +70ºC, or ±75 or 100 ppb from ‒40 to +85ºC. The aging rate is ±100 ppb within one minute for the first year and ±500 ppb within one minute for the first 15 years, both per MIL-PRF-55310. The Allan deviation for frequency versus load is ±5 ppb; for frequency versus voltage, it is also ±5 ppb. They are equipped with electronic frequency control from typically 0 to +4 V dc for a frequency tuning range of ±2 ppm.

Whether with HCMOS or sinewave outputs, the Iris OCXOs provide clean, stable output signals for a fraction of the power consumption of traditional OCXOs. They also add little in weight and size to a circuit design, and help keep satellites stay on time.

Bliley Technologies Inc., 2545 Grandview Blvd., Erie, PA 16506; (814) 838-3571

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