Method of manufacturing a temperature compensated oscillator

• US 20070030084A1
• Filed: 10/10/2006
• Published: 02/08/2007
• Est. Priority Date: 01/21/2002
• Status: Active Grant

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Sakurai, Yasuhiro
• Granted Patent: US 7,583,157 B2
• Time in Patent Office: Days
• US Class Current: 331/176
• CPC Class Codes: H03L 1/026 by using a memory for digitally storing correction values H03L1/025 takes precedence
• CPC Class Codes: H03L 1/027 by using frequency conversion means which is variable with temperature, e.g. mixer, frequency divider, pulse add/substract logic circuit H03L1/023, H03L1/026 take precedence
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H03L 7/183 a time difference being used for locking the loop, the counter counting between fixed numbers or the frequency divider dividing by a fixed number H03L7/1806 takes precedence

Abstract

A method of manufacturing a temperature compensated oscillator including the steps of assembling an oscillator in which an IC chip constituting a temperature compensation circuit with an oscillation circuit and a compensation data storage circuit, and a resonator for the oscillation circuit are mounted in a package; adjusting the resonator with an oscillation frequency of the oscillation circuit to a desired oscillation frequency in condition that the oscillator is kept at a reference temperature, in condition that a temperature compensation function of the temperature compensation circuit is disabled; sealing the resonator hermetically; creating temperature compensation data and storing it into the compensation data storage circuit; and enabling the temperature compensation function of the temperature compensation circuit.

Claims

1. A method of manufacturing a temperature compensated oscillator comprising the steps of:

assembling an oscillator in which an IC chip constituting a temperature compensation circuit with an oscillation circuit and a compensation data storage circuit, and a resonator for said oscillation circuit are mounted in a package,

adjusting said resonator with an oscillation frequency of said oscillation circuit to a desired oscillation frequency in condition that said oscillator is kept at a reference temperature, in condition that a temperature compensation function of said temperature compensation circuit is disabled,

sealing said resonator hermetically,

creating temperature compensation data and storing it into said compensation data storage circuit,

and enabling said temperature compensation function of said temperature compensation circuit.

2. The method of manufacturing a temperature compensated oscillator according to claim 1,

wherein said package is put into a constant temperature chamber in order to keep said oscillator at the reference temperature in the step of adjusting said resonator.

3. The method of manufacturing a temperature compensated oscillator according to claim 1,

wherein said package is put into a constant temperature chamber in the step of creating the temperature compensation data and storing it into said compensation data storage circuit.

4. The method of manufacturing a temperature compensated oscillator according to claim 1,

wherein said temperature compensation data is created based on measurement values gained by measuring the oscillation frequency of said oscillation circuit at each of the temperature states and the difference with respect to said desired oscillation frequency with exposure of said oscillator to a plurality of temperatures, in the step of creating the temperature compensation data and storing it into said compensation data storage circuit.

5. The method of manufacturing a temperature compensated oscillator according to claim 4,

wherein the plurality of temperatures in which said oscillator is exposed to are set at appropriate points in an operation guaranteed temperature range of said oscillator.

6. The method of manufacturing a temperature compensated oscillator according to claim 5,

wherein said operation guaranteed temperature range is from minus 40°

C. to plus 100°

C., and a number of said points is 11.

7. The method of manufacturing a temperature compensated oscillator according to claim 1,

wherein the temperature compensation function is enabled by particular selection information in the step of enabling the temperature compensation function of said temperature compensation circuit.

8. The method of manufacturing a temperature compensated oscillator according to claim 7,

wherein said particular selection information is the information with the pre-assigned combination of a plurality of bits.

9. The method of manufacturing a temperature compensated oscillator according to claim 1,

wherien the step of adjusting said resonator is performed by the steps of:

depositing a metal film on a surface of said resonator allowing a resonant frequency to be lower than the reference frequency in advance, and

applying an ion beam to an electrode film on the surface of said resonator or sputter etching for the electrode film to gradually decrease the mass of the electrode film.