Circuit device, oscillator, real-time clock device, electronic device, and vehicle

Patent metadata

Field	Value
Publication number	US-11038509-B2
Application number	US-202016999318-A
Country	US
Kind code	B2
Filing date	Aug 21, 2020
Priority date	Aug 22, 2019
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A circuit device includes an oscillation circuit and a processing circuit. The oscillation circuit includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to the capacitance value of the variable capacitance circuit. First temperature data and second temperature data subsequent to the first temperature data are input to the processing circuit as temperature data. In the period between the start of the capacitance control based on the first temperature data and the start of the capacitance control based on the second temperature data, the processing circuit switches the first capacitance control data corresponding to the first temperature data and the second capacitance control data different from the first capacitance control data in a time-division manner to be output to the variable capacitance circuit.

First claim

What is claimed is:

1. A circuit device comprising:
an oscillation circuit that includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to a capacitance value of the variable capacitance circuit; and
a processing circuit to which temperature data obtained by A/D converting a temperature detection voltage from a temperature sensor is input and that performs capacitance control on the variable capacitance circuit based on the temperature data, wherein
the processing circuit receives first temperature data as the temperature data and second temperature data subsequent to the first temperature data and switches first capacitance control data corresponding to the first temperature data and second capacitance control data different from the first capacitance control data in a time-division manner in a period between a start of capacitance control based on the first temperature data and a start of capacitance control based on the second temperature data to be output to the variable capacitance circuit, and
the second capacitance control data is data different from the first capacitance control data by a predetermined value.

2. The circuit device according to claim 1 , wherein
the first capacitance control data is first integer data, and
the second capacitance control data is second integer data obtained by adding or subtracting the predetermined value to or from the first integer data.

3. A circuit device comprising:
an oscillation circuit that includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to a capacitance value of the variable capacitance circuit;
a processing circuit to which temperature data obtained by A/D converting a temperature detection voltage from a temperature sensor is input and that performs capacitance control on the variable capacitance circuit based on the temperature data, wherein
the processing circuit receives first temperature data as the temperature data and second temperature data subsequent to the first temperature data and switches first capacitance control data corresponding to the first temperature data and second capacitance control data different from the first capacitance control data in a time-division manner in a period between a start of capacitance control based on the first temperature data and a start of capacitance control based on the second temperature data to be output to the variable capacitance circuit; and
a memory that stores time-division pattern information, wherein
the processing circuit switches the first capacitance control data and the second capacitance control data in a time-division manner based on the time-division pattern information read from the memory to be output to the variable capacitance circuit.

4. The circuit device according to claim 3 , wherein
the memory stores the temperature data and a capacitance adjustment value of the variable capacitance circuit in association with each other and stores decimal data of the capacitance adjustment value and the time-division pattern information in association with each other,
the processing circuit reads the capacitance adjustment value corresponding to the temperature data from the memory and reads the time-division pattern information corresponding to the decimal data of the read capacitance adjustment value from the memory, and
the processing circuit switches the first capacitance control data based on the capacitance adjustment value read from the memory, and the second capacitance control data that is integer data obtained by adding or subtracting a predetermined value to or from the first capacitance control data in a time-division manner based on the time-division pattern information read from the memory to be output to the variable capacitance circuit.

5. The circuit device according to claim 1 , further comprising:
a memory that stores the temperature data and a capacitance adjustment value of the variable capacitance circuit in association with each other, wherein
the processing circuit obtains a capacitance adjustment value corresponding to the temperature data by reading a first capacitance adjustment value and a second capacitance adjustment value corresponding to upper bits of the temperature data and linearly interpolating the first capacitance adjustment value and the second capacitance adjustment value based on lower bits of the temperature data, and
the processing circuit switches the first capacitance control data that is integer data of the capacitance adjustment value and the second capacitance control data in a time-division manner based on decimal data of the capacitance adjustment value to be output to the variable capacitance circuit.

6. The circuit device according to claim 1 , wherein
the processing circuit includes a digital filter that performs digital filtering on the temperature data, and
the processing circuit controls the capacitance value of the variable capacitance circuit based on the temperature data after the digital filter processing.

7. The circuit device according to claim 1 , wherein
the capacitor array includes
first to n-th capacitors (n is an integer of 2 or more) weighted in binary,
first to n-th switches having one end coupled to one end of the first to n-th capacitors and the other end coupled to an output node or an input node of a drive circuit of the oscillation circuit,
a switching capacitor, and
a switching switch having one end coupled to one end of the switching capacitor and the other end coupled to the output node or the input node of the drive circuit,

on/off states of the first to n-th switches do not change between when the first capacitance control data is input and when the second capacitance control data is input, and
the switching switch is turned to one of on or off when the first capacitance control data is input, and is turned to the other of on or off when the second capacitance control data is input.

8. An oscillator comprising:
the circuit device according to claim 1 ; and
a resonator that is electrically coupled to the oscillation circuit and oscillates by the oscillation circuit.

9. A real-time clock device comprising:
a temperature sensor that generates a temperature detection voltage;
an A/D conversion circuit that generates temperature data by A/D converting the temperature detection voltage;
an oscillation circuit that includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to a capacitance value of the variable capacitance circuit;
a memory that stores a capacitance adjustment value corresponding to the temperature data;
a processing circuit that controls the capacitance value of the variable capacitance circuit based on the temperature data and the capacitance adjustment value; and
a clocking circuit that generates time information based on a clock signal output from the oscillator circuit, wherein
the capacitor array includes a plurality of capacitors and a switching switch that is coupled to one of the plurality of capacitors, and
the processing circuit controls the capacitance value of the variable capacitance circuit with a resolution smaller than a minimum capacitance value of the plurality of capacitors by controlling the switching switch in a time-division manner.

10. The real-time clock device according to claim 9 , wherein
the processing circuit is configured to
perform digital filtering on the temperature data, and
obtain the capacitance adjustment value corresponding to the digitally filtered temperature data by performing interpolation processing on the capac

Assignees

• Seiko Epson Corp

Inventors

• Takahashi Tomoaki
• Sudo Yasuhiro

Classifications

• G04G3/04 Primary

  Temperature-compensating arrangements · CPC title

• H03B2201/025

  the means being an electronic switch for switching in or out oscillator elements · CPC title

• H03M1/66

  Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• G04F10/005

  Time-to-digital converters [TDC] (analog-to-digital converters with intermediate conversion to time or phase H03M1/50, H03M1/60) · CPC title

• H03J5/0218

  Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, by selecting the corresponding analogue value between a set of preset values · CPC title