The CF5011 series are low-voltage crystal oscillator module ICs that operate at 1.8V. The crystal oscillator circuit and output buffer employ a low-voltage CMOS process operating at 1.8V. The crystal oscillator circuit has a built-in thin-film feedback resistor with good temperature characteristics and built-in capacitors with excellent frequency response, making possible a stable 3rd-harmonic oscillator with only the addition of a crystal element.