Small-sized rubidium oscillator

Demand for a small, extremely steady base frequency source is rising as the result of the miniaturization of communication devices that support ISDN and the development of positioning systems such as GPS. Answering this need, NEC has developed the Rb-5000 rubidium atomic oscillator, a compact, light, and low-consumption oscillator. The Rb-5000 uses an especially miniaturized high-frequency block and cavity design, employing principally the following three new technologies. First, the Rb-5000 uses a small 760 MHz PLL module, eliminating the multiplier conventionally used as a servo circuit. Second, it integrates the frequency generator of the phase modulation block and 5.3 MHz frequency synthesizer, and the control of the 760 MHz PLL module into one chip. Third, the efficiency of the microwave mode is raised by designing a gold-plated printed board as part of the cavity, on which a 6.8 GHz transmission antenna, 6.8 GHz monitor antenna, 9× multiplier, and photo detector are formed in a compact design. Through the use of the above-described technologies, the Rb-5000 achieves a size of only 300 cc, a weight of approximately 600 grams, and a power consumption of 8 W, while maintaining almost the same performance level as the previous type rubidium atomic oscillators