US Patent No. 9,077,347

OVEN CONTROLLED CRYSTAL OSCILLATOR


Patent No. 9,077,347
Issue Date July 07, 2015
Title Oven Controlled Crystal Oscillator
Inventorship Takahiro Yoshimura, Saitama (JP)
Junichi Arai, Saitama (JP)
Assignee NIHON DEMPA KOGYO CO., LTD., Tokyo (JP)

Claim of US Patent No. 9,077,347

1. An oven controlled crystal oscillator, comprising:
a crystal unit;
a temperature control circuit configured to control a temperature of the crystal unit; and
a circuit board on which the crystal unit and the temperature control circuit are mounted, wherein
the crystal unit includes a flange that projects outward to an entire outer periphery in one end, and
the circuit board includes a depressed portion in which the flange is partially inserted, wherein
the crystal unit is positioned in a state where the flange is partially inserted in the depressed portion, the crystal unit
being connected to a metal pattern,

wherein the temperature control circuit includes:
a heater resistance having one end, a supply voltage being supplied to the one end to generate heat;
a thermistor having one end and another end, the supply voltage being supplied to the one end, the other end being grounded,
the thermistor being a temperature sensor with a variable resistance value depending on temperature, the thermistor outputting
a voltage corresponding to the temperature to the one end;

a differential amplifier configured to: receive a voltage between the supply voltage and the one end of the thermistor at
one input terminal of the differential amplifier; receive a voltage of a signal line disposed in parallel in the thermistor
at another input terminal of the differential amplifier; and amplify a difference between the voltage input to the other input
terminal and the voltage input to the one input terminal to output as a control voltage, the output of the differential amplifier
being inputted to the one input terminal as feedback via a resistance;

a PNP type power transistor that includes: an emitter to which the other end of the heater resistance is connected; a base
that receives the output of the differential amplifier; and a collector that is grounded; and

a PNP type current ng transistor that includes: an emitter that receives the supply voltage; a base that receives the voltage
between the other end of the heater resistance and the emitter of the power transistor; and a collector connected to the base
of the power transistor, wherein

the collector of the power transistor and the other end of the thermistor are connected and grounded by the metal pattern
that commonly connect.