The SM5073 series are VCXO ICs with built-in varicap diode. They use a recently developed negative-resistance switching oscillation circuit, at oscillation startup and during normal oscillation, for both good oscillation startup characteristics and wide pullrange. Furthermore, it employs a CMOS process varicap diode, and also features all the necessary VCXO structure circuit components on a single chip, forming a VCXO with just the connection of an external crystal.