Temperature-compensated oscillator and electronic device

• US 8,680,933 B2
• Filed: 05/02/2012
• Issued: 03/25/2014
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Terasawa, Katsuyoshi
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US13/462,148
• Publication Number:
  US 20120286890A1
• Time in Patent Office: 692 Days
• Field of Search: 310/315, 310/346, 331/154, 331/156, 331/158, 331/176, 331/186
• US Class Current: 331/176
• CPC Class Codes: H03L 1/022 by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence

Abstract

A temperature-compensated oscillator includes a temperature sensor, a temperature compensation circuit, a voltage-controlled oscillation circuit adapted to output an oscillation signal on which temperature compensation is performed based on the temperature compensation voltage, an output circuit adapted to output an ON/OFF signal based on a relationship between variation of the detected-temperature voltage output by the temperature sensor and a reference voltage, a switch circuit adapted to supply the temperature compensation circuit with electrical power in response to the ON/OFF signal, and a sample-and-hold circuit adapted to be switched between a state of outputting the temperature compensation voltage to the voltage-controlled oscillation circuit while holding the temperature compensation voltage output by the temperature compensation circuit, and a state of outputting the temperature compensation voltage held to the voltage-controlled oscillation circuit while cutting the connection to the temperature compensation circuit in response to the ON/OFF signal.

Claims

1. A temperature-compensated oscillator comprising:

a temperature sensor adapted to output a detected-temperature voltage corresponding to temperature;

a temperature compensation circuit adapted to output a temperature compensation voltage based on the detected-temperature voltage;

a voltage-controlled oscillation circuit adapted to output an oscillation signal on which temperature compensation is performed based on the temperature compensation voltage;

an output circuit adapted to output an ON/OFF signal based on a magnitude relation between an amplitude of a voltage variation in the detected-temperature voltage in a desired period and a reference voltage;

a switch circuit adapted to perform ON/OFF control on power supply to the temperature compensation circuit in response to the ON/OFF signal; and

a sample-and-hold circuit controlled to be switched between

a state of outputting the temperature compensation voltage to the voltage-controlled oscillation circuit while holding the temperature compensation voltage output by the temperature compensation circuit, and

a state of outputting the temperature compensation voltage held to the voltage-controlled oscillation circuit while cutting the connection to the temperature compensation circuit in response to the ON/OFF signal.

2. The temperature-compensated oscillator according to claim 1, wherein

the output circuit includes

a low-pass filter to which the detected-temperature voltage is input,

a differential amplifier circuit adapted to perform differential amplification on an output of the temperature sensor and an output of the low-pass filter to thereby output a voltage corresponding to the voltage variation,

an absolute value circuit adapted to output a voltage representing an absolute value of an output of the differential amplifier circuit to thereby output a voltage corresponding to an amplitude of the voltage variation, and

a comparator adapted to output a signal, which represents a magnitude relation between an output of the absolute value circuit and the reference voltage, as the ON/OFF signal.

3. The temperature-compensated oscillator according to claim 1, wherein

the output circuit includes

a timer adapted to output a drive signal at a constant period,

a second sample-and-hold circuit which can be switched between a state of outputting the detected-temperature voltage while connecting to the temperature sensor, and holding the detected-temperature voltage, and a state of outputting the detected-temperature voltage held while cutting the connection with the temperature sensor,

a differential amplifier circuit adapted to perform differential amplification on an output of the temperature sensor and an output of the second sample-and-hold circuit to thereby output a voltage corresponding to the voltage variation,

an absolute value circuit adapted to output a voltage representing an absolute value of an output of the differential amplifier circuit to thereby output a voltage corresponding to an amplitude of the voltage variation, and

a comparator adapted to output a signal, which represents a magnitude relation between an output of the absolute value circuit and the reference voltage, as the ON/OFF signal.

4. The temperature-compensated oscillator according to claim 2, wherein

the output circuit includes a blocking circuit adapted to block the ON/OFF signal if the detected-temperature voltage is a value between a first threshold voltage previously set, and a second threshold voltage set previously and higher than the first threshold voltage.

5. The temperature-compensated oscillator according to claim 2, wherein

the output circuit includes

a delay circuit to which the ON/OFF signal is input, and which outputs a delay signal obtained by delaying a voltage variation in the ON/OFF signal,

an OR circuit adapted to output a signal representing an OR result between the ON/OFF signal and the delay signal to the switch circuit as the ON/OFF signal, and

an AND circuit adapted to output a signal representing an AND result between the ON/OFF signal and the delay signal to the sample-and-hold circuit as the ON/OFF signal.

6. The temperature-compensated oscillator according to claim 1, further comprising:

a second low-pass filter disposed one of between the temperature compensation circuit and the sample-and-hold circuit, and between the sample-and-hold circuit and the voltage-controlled oscillation circuit.

7. An electronic device comprising:

the temperature-compensated oscillator according to claim 1.

8. An electronic device comprising:

the temperature-compensated oscillator according to claim 2.

9. An electronic device comprising:

the temperature-compensated oscillator according to claim 3.