Most integrated circuits for Bluetooth applications need an external precision frequency source that can be multiplied up to around 2.45GHz. There are also pressures for minimum size, good shock resistance, high reliability, low aging and infrared reflow soldering capability.

Advanced Crystal Technology is asked for frequencies of 12, 13, 16, 26, and 32MHz for this application and all parts are required to run in fundamental resonance mode. Frequency tolerance at 25°C is usually ±10ppm, with a frequency stability over the operating temperature (typically –20 to +70 C) adding another 9 or 10ppm. To minimise the effects of temperature drift and aging, the output frequency can be tuned. Load capacitance of these crystals is relatively low at around 9pF, and the change in frequency for a change in load capacitance, usually described as pulling sensitivity, is at least 15ppm/pF. So the integrated circuit changing the load capacitance in its oscillator by 1pF can correct for a near 80°C change in temperature.

Available device sizes form Advanced Crystal technology include 7 x 5 mm, 6 x 3.5mm, 5 x 3.2mm, 4 x 2.5mm, and 3.2 x 2.5mm. Likely developments will introduce parts in 2.5 x 2.0mm and 2.0 x 1.6mm packages. The material is metal lid seam welded on ceramic substrate in LCC.

Please contact your distributor or Advanced Crystal Technology directly with your Bluetooth frequency source needs.