Constant temperature crystal oscillator

摘要

A constant temperature crystal oscillator includes on a circuit substrate (3) : a surface-mount crystal resonator (1A) which is provided with two crystal terminals (9a) as mount terminals and a dummy terminal (9b) on the bottom surface, and has a metal cover (8); an oscillation circuit element (1) which forms an oscillation circuit together with the crystal resonator (1A); and a temperature control element (2) which keeps a constant operation temperature of the crystal resonator (1A), in which the temperature control element (2) includes at least a heating chip resistor (2a), a power transistor (2b) for supplying electric power to the chip resistor (2a), and a temperature sensitive resistor (2c) for detecting the operation temperature of the crystal resonator (1A), wherein a dummy terminal (14x) on the substrate side of the circuit substrate for connection to the dummy terminal (9b) of the crystal resonator (1A) is connected to a resistor terminal (14y) on the substrate side to which the temperature sensitive resistor (2c) is connected through a conductive path (14z).