High frequency fundamental VCXO for SDH system

This paper describes a high frequency fundamental (HFF) crystal resonator in the frequency range from 156 MHz to nearly 1 GHz, which is fabricated by an industrial photolithographic batch manufacturing process with chemical etching. It also describes a 156 MHz voltage controlled crystal oscillator (VCXO) and a 622 MHz VCXO employing the prototype HFF crystal resonators developed for SDH (synchronous digital hierarchy) system. The 155 MHz HFF-VCXO has been constructed in an industrially standardized 14-pin dual in-line package (DIP) of 20.8 mm×13.2 mm×7.1 mm (volume 1.4 cc) that is one-seventh as big as that of a conventional third overtone mode VCXO. It is composed of a prototype 156 MHz HFF crystal resonator, an emitter coupled logic (ECL) IC and a varactor diode. It still provides the same characteristic as a conventional oscillator. Also, a compact 622 MHz HFF-VCXO with ECL level output has been developed utilizing the same circuit and package as those of the 156 MHz HFF-VCXO, which provides a frequency deviation of approximately ±150 ppm versus control voltage change at 2.5 V±2 V, and then, a temperature frequency stability of less than ±50 ppm over the range from -40°C to +85°C