The NJM2555 is a 622.08MHz VCXO (Voltage Controlled Crystal Oscillator) IC designed for optical fiber telecommunication systems, using NewJRC superior Bipolar technology, which consists of an oscillation amplifier, a variable capacitor diode, a quadruple (x4) frequency circuit, high pass filter, and limiter amplifier. The NJM2555 generate x4 frequency to add the only 155.52MHz crystal and LC filter, and the output is differential NJM2555C-C