Citizen Watch Company, Ltd.

Citizen Holdings Company, Ltd.

Yasuhiro Sakurai

Hiroyuki Fukayama

Toshiyuki Kishi

Kiyoshi Nobuoka

Hiroki Nishi

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.

Method of manufacturing a temperature compensated oscillator

The temperature of an oscillation circuit ( ) is detected by a temperature detection circuit ( ), a cubic term voltage generation circuit of a control voltage generation circuit ( ) generates a cubic term voltage as a control voltage based on an output voltage of the temperature detection circuit ( ), and a frequency adjustment circuit ( ) changes an oscillation frequency of the oscillation circuit ( ) by the control voltage. The cubic term voltage generation circuit includes a first MOS transistor ( ) having a source connected to a first power line ( ), a second MOS transistor ( ) having a source connected to a second power line ( ), and digital control voltage division circuits ( ) for generating a first and a second gate voltage, respectively based on the output voltage of the temperature detection circuit ( ), in which the first and second gate voltages are applied to gates of the first and second MOS transistors ( ) respectively, and a connection point ( ) where respective drains are commonly connected shall be an output terminal of the control voltage.

Temperature compensated oscillator using a control voltage generation circuit

An insulating film and a conducting film are formed in that order on an N type semiconductor substrate to form a capacitor structure of &ldquo;conducting film&mdash;insulating film&mdash;semiconductor&rdquo;; a heavily doped P region having a high impurity concentration is provided on the N type semiconductor substrate to contact a covered region which is covered with the conducting film; and furthermore a heavily doped N region for conducting an electrode on the semiconductor side is provided and connected with the heavily doped P region, resulting in quickly variance of the capacitance values in accordance with the voltage applied between the heavily doped N region and a terminal of the conducting film.

Mis variable capacitor and temperature-compensated oscillator using the same

A constant voltage generation circuit (,) for driving a temperature-compensated crystal oscillation circuit (,) comprises a differential circuit (,), a dc load (,) for supplying feedback signals to the differential circuit (,), a driver (,) for driving the dc load (,) and the temperature-compensated crystal oscillation circuit (,) under control by control signals outputted by the differential circuit (,), and a low-pass filter (,) made up of passive elements only and for applying the control signals to the driver (,) after removing high frequency components out of the control signals, thereby preventing an increase of phase noise while achieving low power consumption.

Temperature-compensated crystal oscillator having constant voltage generator with filter

In a temperature-compensated crystal oscillator wherein a temperature-compensated crystal oscillation circuit is driven by a constant voltage generation circuit, the constant voltage generation circuit comprises a differential circuit, a dc load for supplying feedback signals to the differential circuit, a first driver for driving the dc load under control of the differential circuit, a phase-compensation capacitor coupled between a control terminal of the first driver and an output terminal thereof and a second driver for driving the temperature-compensated crystal oscillation circuit. The second driver is the same kind of device as is used for the first driver, and is under control by the same control signal as a control signal for the first driver, sent out by the differential circuit.

Temperature-compensated crystal oscillator

In a temperature-compensated crystal oscillator, a series connection of an AT-cut crystal resonator, a MOS capacitor, and a first fixed capacitor is coupled in parallel with an amplifier and a second fixed capacitor, making up a crystal oscillation circuit. A first control signal generating circuit for temperature compensation is connected directly or via a first input resistor to one terminal of the MOS capacitor of the crystal oscillation circuit, and a second control signal generating circuit for temperature compensation is connected dirty or via a second input resistor to the other terminal of the MOS capacitor. The first control signal generating circuit serves as a rectilinear correction signal generating circuit on the lower temperature side while the second control signal generating circuit serves as a rectilinear correction signal generating circuit on the higher temperature side.

The invention provides a temperature-compensated crystal oscillator employing an AT-cut crystal resonator in a crystal oscillation circuit, having a substantially constant oscillation frequency at approximately room temperature, wherein an output of a temperature sensor, having a substantially rectilinear temperature characteristic, is converted into square-law cure signals by a square-law converter circuit on the lower temperature side and a square-law converter circuit on the higher temperature side, respectively, which are then combined together by a signal synthesis circuit, producing a rectilinear correction signal. Frequency adjustment circuits are controlled by the signal, and temperature compensation is achieved by executing rectilinear correction of the oscillation frequency of the crystal oscillation circuit. In the case where the oscillation frequency of the AT-cut crystal resonator has a temperature characteristic having any gradient, a gradient is added to the rectilinear correction signal.

Temperature-compensated crystal oscillator using square-law converter

In a temperature sensor, between a first power supply and a second power supply, there are disposed a resistor group consisting of a plurality of resistors connected in series and a MOS transistor in the form of a temperature transducer, the resistor group being connected in series with the MOS transistor having a drain connected to the resistor group and having a source and a bulk which are connected to the first power supply. The temperature sensor further comprises a switch group consisting of switches for opening and closing the connections between the connection points of the adjacent resistors of the resistor group and the second power supply, an external terminal connected to the drain of the MOS transistor, a temperature-compensated constant voltage generating circuit for generating a gate voltage as an output voltage to the MOS transistor, and a non-volatile memory which stores therein data for adjusting the output voltage from the temperature-compensated constant voltage generating circuit and the state of opening and closing of the switches of the switch group. With the voltage at the second power supply as the reference, the drain voltage at the MOS transistor is output as temperature information to the external terminal.

Temperature sensor and method of adjusting the same

A phase and base potential converter according to the invention is constructed as follows. Two MOS transistors having the same size and characteristic are connected in series between a first power supply and a second power supply, a gate of one MOS transistor is served as an input terminal of a voltage based on the first power supply, and a source of the other MOS transistor is served as an output terminal of a voltage based on the second power supply. One of the first power supply or the second power supply is a lower potential power supply, and the other is a higher potential power supply. The phase and base potential converter being thus constructed makes it possible to convert, for example, a signal based on the Vss into a signal based on the Vdd and thereby synthesize signals having different base potentials.

Phase and base potential converter and temperature-compensated crystal

A temperature compensated crystal oscillator comprises a crystal oscillating circuit having an AT-cut crystal resonator; a linearizing correction circuit for transforming a temperature characteristic curve of an oscillating frequency of the crystal resonator into a straight line using a fixed coefficient common to all crystal resonators; a gradient correction circuit for eliminating the gradient of the linearized temperature characteristic of the oscillating frequency usmg a variable coefficient depending on the type of crystal resonator; and an f0 adjustment circuit for adjusting the gradient corrected temperature characteristic of the oscillating frequency so as to cause the oscillating frequency to lie within an allowable range. Thus, upon the temperature compensation of the oscillating frequency, there are separately performed the linearizing correction, the gradient correction and the f0 adjustment, to achieve a fast temperature compensation adjustment of the oscillating frequency.

Temperature compensation crystal oscillator

Between the higher-potential power supply and the lower-potential power supply, a pair of first conductivity type MOS transistors having same configurations except for mutually different work functions of the gate electrode and another pair of second conductivity type MOS transistors having the same properties are provided to constitute a differential amplifier. The drain of the other MOS transistor having the second conductivity type is connected to the output terminal and, at the same time, is connected to the higher-potential power supply via a resistor circuit, thereby connecting the gate of one of the above-mentioned pairs of MOS transistors with the first conductivity type to the intermediate point of the resistor circuit. With this, the differential amplifier outputs at its output terminal a voltage corresponding to a difference in gate work function of the pair of MOS transistors having the first conductivity type.

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Sayama, Japan

Yasuhiro Sakurai