阅读说明：本技术 半导体装置、机芯以及电子钟表 (Semiconductor device, movement, and electronic timepiece ) 是由 二宫正也 于 2019-08-27 设计创作，主要内容包括：本发明提供一种能够防止振荡开始时的因闭环而导致的导致自激振荡的发生的半导体装置、机芯以及电子钟表。半导体装置具备振荡电路以及控制电路。振荡电路具备：与振子连接的输入端子以及输出端子；直流切断电容器,其两个端子中的一个端子被连接于所述输入端子上；反相器,其输入侧被连接于所述直流切断电容器的另一个端子且输出侧被连接于所述输出端子；第一反馈电阻,其与所述反相器并联连接；第二反馈电阻,其与所述直流切断电容器以及所述反相器并联连接；开关,其与所述直流切断电容器并联连接。控制电路在所述振子的振荡开始时,使所述开关短路,并且在从所述振荡开始起经过预定时间之后,使所述开关断开。(The invention provides a semiconductor device, a movement, and an electronic timepiece, which can prevent self-oscillation caused by a closed loop at the start of oscillation. The semiconductor device includes an oscillation circuit and a control circuit. The oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current blocking capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a switch connected in parallel with the DC cut capacitor. The control circuit short-circuits the switch at the start of oscillation of the oscillator, and turns off the switch after a predetermined time has elapsed from the start of oscillation.)

1. A semiconductor device is characterized by comprising an oscillation circuit and a control circuit,

the oscillation circuit includes:

an input terminal and an output terminal to which the vibrator is connected;

a direct current blocking capacitor having one terminal connected to the input terminal;

an inverter connected between the other terminal of the dc cut capacitor and the output terminal;

a first feedback resistor connected in parallel with the inverter;

a second feedback resistor connected in parallel to the dc cut capacitor and the inverter;

a switch connected in parallel with the DC cut-off capacitor,

the control circuit short-circuits the switch at a start of oscillation of the oscillator, and turns off the switch after a predetermined time has elapsed from the start of oscillation.

2. A semiconductor device is characterized by comprising an oscillation circuit and a control circuit,

the oscillation circuit includes:

a vibrator input terminal and an output terminal are connected;

a direct current blocking capacitor having one terminal connected to the input terminal;

an inverter connected between the other terminal of the dc cut capacitor and the output terminal;

a first feedback resistor connected in parallel with the inverter;

a second feedback resistor connected in parallel to the dc cut capacitor and the inverter;

a first switch connected in parallel to the dc cut capacitor;

a second switch connected between an input side of the first feedback resistance and an input side of the inverter;

a third switch connected between the output side of the inverter and a space between the second switch and the first feedback resistor;

a fourth switch connected between output sides of the first and second feedback resistors and an output side of the inverter,

the control circuit, when oscillation of the oscillator starts, short-circuits the first switch and the third switch and turns off the second switch and the fourth switch, and, after a predetermined time has elapsed from the start of oscillation, turns off the first switch and the third switch and short-circuits the second switch and the fourth switch.

3. A semiconductor device is characterized by comprising an oscillation circuit and a control circuit,

the oscillation circuit includes:

an input terminal and an output terminal to which the vibrator is connected;

a direct current blocking capacitor having one terminal connected to the input terminal;

an inverter connected between the other terminal of the dc cut capacitor and the output terminal;

a first feedback resistor connected in parallel with the inverter;

a second feedback resistor connected in parallel to the dc cut capacitor and the inverter;

a first switch connected in parallel to the dc cut capacitor;

a second switch connected between an input side of the second feedback resistance and an input side of the dc cut capacitor;

a third switch connected between the output side of the inverter and a space between the second switch and the second feedback resistor;

a fourth switch connected between output sides of the first and second feedback resistors and an output side of the inverter,

the control circuit, when oscillation of the oscillator starts, short-circuits the first switch and the third switch and turns off the second switch and the fourth switch, and, after a predetermined time has elapsed from the start of oscillation, turns off the first switch and the third switch and short-circuits the second switch and the fourth switch.

4. A machine core is characterized in that a machine core is provided,

a semiconductor device according to any one of claims 1 to 3 is provided.

5. An electronic timepiece is characterized in that,

a semiconductor device according to any one of claims 1 to 3 is provided.

Technical Field

The invention relates to a semiconductor device, a movement and an electronic timepiece.

Background

As an oscillation circuit capable of stably oscillating a vibrator such as a quartz-crystal vibrator and having a small fluctuation in oscillation frequency, an oscillation circuit shown in fig. 3 of patent document 1 is known. The oscillation circuit includes an oscillation inverter connected to the oscillator via a signal path, and a first feedback resistor connected to an input/output side of the oscillation inverter. Further, a DC (Direct Current) cut capacitor is provided as a countermeasure for stopping oscillation due to leakage Current occurring at the input terminal of the oscillator. When the DC cut capacitor is provided on the input terminal side of the signal path, the potential on the input terminal side is not fixed because the potential is close to open, and therefore the parasitic capacitance is varied by the occurrence of a leakage current due to the influence of humidity or the like, and the oscillation frequency is varied. In order to prevent this oscillation frequency variation, the input terminal of the signal path and the output terminal of the inverter are connected by a second feedback resistor.

However, in the oscillation circuit of patent document 1, in addition to the oscillation by the crystal oscillator, the closed-loop self-oscillation occurs due to the oscillation inverter and the first feedback resistor, and thus there is a problem that appropriate oscillation cannot be generated.

Patent document 1: japanese patent laid-open publication No. 2004-96711

Disclosure of Invention

An oscillation circuit according to the present invention includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a switch connected in parallel with the DC cut capacitor.

An oscillation circuit according to the present invention includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected between an input side of the first feedback resistance and an input side of the inverter; a third switch connected between the output side of the inverter and a space between the second switch and the first feedback resistor; a fourth switch connected between output sides of the first and second feedback resistors and an output side of the inverter.

An oscillation circuit according to the present invention includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected between an input side of the second feedback resistance and an input side of the dc cut capacitor; a third switch connected between the output side of the inverter and a space between the second switch and the second feedback resistor; a fourth switch connected between output sides of the first and second feedback resistors and an output side of the inverter.

An oscillation circuit according to the present invention includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistance composed of a variable resistor connected in parallel with the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected in series with the first feedback resistor; and a third switch that changes the variable resistance value of the second feedback resistor by switching between a short-circuit state and an open state.

An oscillation circuit according to the present invention includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistance composed of a variable resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected in series with the second feedback resistor; and a third switch that changes the variable resistance value of the first feedback resistor by switching between a short-circuit state and an open state.

The present invention is a semiconductor device including an oscillation circuit and a control circuit, wherein the oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; and a switch connected in parallel with the dc cut capacitor, wherein the control circuit short-circuits the switch at a start of oscillation of the oscillator and turns off the switch after a predetermined time has elapsed from the start of oscillation.

The present invention is a semiconductor device including an oscillation circuit and a control circuit, wherein the oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected between an input side of the first feedback resistance and an input side of the inverter; a third switch connected between the output side of the inverter and a space between the second switch and the first feedback resistor; and a fourth switch connected between an output side of the first and second feedback resistors and an output side of the inverter, wherein the control circuit, when oscillation of the oscillator starts, short-circuits the first and third switches and turns off the second and fourth switches, and, after a predetermined time has elapsed from the start of oscillation, turns off the first and third switches and short-circuits the second and fourth switches.

The present invention is a semiconductor device including an oscillation circuit and a control circuit, wherein the oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected between an input side of the second feedback resistance and an input side of the dc cut capacitor; a third switch connected between the output side of the inverter and a space between the second switch and the second feedback resistor; and a fourth switch connected between an output side of the first and second feedback resistors and an output side of the inverter, wherein the control circuit, when oscillation of the oscillator starts, short-circuits the first and third switches and turns off the second and fourth switches, and, after a predetermined time has elapsed from the start of oscillation, turns off the first and third switches and short-circuits the second and fourth switches.

The present invention is a semiconductor device including an oscillation circuit and a control circuit, wherein the oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistor connected in parallel with the inverter; a second feedback resistor including a variable resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected in series with the first feedback resistor; and a third switch that changes a variable resistance value of the second feedback resistance by switching between a short-circuit state and an open state, wherein the control circuit, when oscillation of the oscillator starts, short-circuits the first switch, turns off the second switch, and sets the third switch to one of the short-circuit state and the open state, and, after a predetermined time has elapsed from the start of the oscillation, turns off the first switch, short-circuits the second switch, and sets the third switch to the other of the short-circuit state and the open state.

The present invention is a semiconductor device including an oscillation circuit and a control circuit, wherein the oscillation circuit includes: an input terminal and an output terminal connected to the vibrator; a direct current cutoff capacitor having one of two terminals connected to the input terminal; an inverter having an input side connected to the other terminal of the dc cut capacitor and an output side connected to the output terminal; a first feedback resistance composed of a variable resistor connected in parallel with the inverter; a second feedback resistor connected in parallel to the dc cut capacitor and the inverter; a first switch connected in parallel to the dc cut capacitor; a second switch connected in series with the second feedback resistor; and a third switch that changes a variable resistance value of the first feedback resistance by switching between a short-circuit state and an open state, wherein the control circuit, when oscillation of the oscillator starts, short-circuits the first switch and opens the second switch, and sets the third switch to one of the short-circuit state and the open state, and, after a predetermined time has elapsed from the start of the oscillation, opens the first switch and short-circuits the second switch, and sets the third switch to the other of the short-circuit state and the open state.

The movement of the present invention is characterized by including the semiconductor device.

An electronic device according to the present invention is provided with the semiconductor device.

Drawings

Fig. 1 is a front view of an electronic timepiece according to an embodiment of the present invention.

Fig. 2 is a block diagram showing a structure of a movement according to an embodiment of the present invention.

Fig. 3 is a circuit diagram showing an oscillation circuit at the start of oscillation according to the first embodiment.

Fig. 4 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the first embodiment.

Fig. 5 is a flowchart showing a control process of the oscillation circuit according to the first embodiment.

Fig. 6 is a circuit diagram showing an oscillation circuit at the start of oscillation according to the second embodiment.

Fig. 7 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the second embodiment.

Fig. 8 is a flowchart showing a control process of the oscillation circuit according to the second embodiment.

Fig. 9 is a circuit diagram showing an oscillation circuit at the start of oscillation according to the third embodiment.

Fig. 10 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the third embodiment.

Fig. 11 is a flowchart showing a control process of the oscillation circuit according to the third embodiment.

Fig. 12 is a circuit diagram showing an oscillation circuit at the start of oscillation according to the fourth embodiment.

Fig. 13 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the fourth embodiment.

Fig. 14 is a circuit diagram showing an oscillation circuit at the start of oscillation in the fifth embodiment.

Fig. 15 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the fifth embodiment.

Fig. 16 is a circuit diagram showing an oscillation circuit at the start of oscillation in the first modification.

Fig. 17 is a circuit diagram showing an oscillation circuit when oscillation is stable according to the first modification.

Fig. 18 is a circuit diagram showing an oscillation circuit at the start of oscillation in the second modification.

Fig. 19 is a circuit diagram showing an oscillation circuit when oscillation is stable in the second modification.

Fig. 20 is a circuit diagram showing an oscillation circuit at the start of oscillation in the third modification.

Fig. 21 is a circuit diagram showing an oscillation circuit when oscillation is stable in the third modification.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First embodiment

As shown in fig. 1, the electronic timepiece 1 is a wristwatch worn on a wrist of a user, and includes an outer case 2, a disc-shaped dial 3, a second hand 5, a minute hand 6, an hour hand 7, which are hands driven by a movement not shown, and a crown 8, which is an operation member. The date display and the second hand 5 are not essential, and the electronic timepiece 1 may not include a date display member such as a date wheel and a day wheel and the second hand 5.

The movement of the electronic timepiece 1 includes a semiconductor device 10 including a CMOS (Complementary Metal Oxide semiconductor integrated Circuit) or the like. As shown in fig. 2, the semiconductor device 10 includes an oscillation circuit 20, a high-frequency dividing circuit 11, a low-frequency dividing circuit 12, a drive circuit 13, a constant voltage circuit 14, and a control circuit 15. The drive circuit 13 is a circuit for driving the stepping motor 16, and the stepping motor 16 moves the second hand 5, the minute hand 6, and the hour hand 7 through a drive train wheel not shown. In addition, CMOS is an abbreviation of Complementary Metal Oxide Semiconductor (CMOS).

The oscillation circuit 20 is a circuit for oscillating the crystal oscillator 18 as a vibration source, and is integrally formed on a semiconductor substrate, and the crystal oscillator 18 is connected to an input terminal G and an output terminal D of a signal path thereof.

As shown in fig. 3 and 4, the oscillation circuit 20 includes an inverter 21, a first feedback resistor 25, a second feedback resistor 26, a dc cut capacitor 27, a first electrostatic protection circuit 31, a second electrostatic protection circuit 32, and a switch 50. The DC cut capacitor 27 will be referred to as a DC cut capacitor 27 in the following description.

The inverter 21 is an oscillation inverter formed of a P-channel MOSFET22 and an N-channel MOSFET 23. The MOSFET is an abbreviation of Metal-Oxide-Semiconductor Field Effect Transistor.

The first feedback resistor 25 is a resistor connected in parallel to the inverter 21, and causes the inverter 21 to function as an amplifier.

The second feedback resistor 26 is connected in parallel to the inverter 21 and the DC cut capacitor 27. As shown in fig. 3, in the case where the switch 50 is short-circuited, that is, in the case where the switch 50 is set to the on state, the second feedback resistance 26 forms a signal path bypassing the DC cut capacitor 27, and is connected in parallel with the first feedback resistance 25. Therefore, the feedback resistor of the inverter 21 is composed of the first feedback resistor 25 and the second feedback resistor 26 connected in parallel, and if the combined resistance value is R, the resistance value of the first feedback resistor 25 is R1, and the resistance value of the second feedback resistor 26 is R2, R is (R1 × R2)/(R1+ R2). If R1 ═ R2, then R ═ R1/2.

As shown in fig. 4, the second feedback resistor 26 functions as a circuit for stabilizing the potential of the input terminal G, which has an unfixed potential because the DC cut capacitor 27 is provided to approach an OPEN circuit (OPEN) state when the switch 50 is off, that is, when the switch 50 is in an off state.

Therefore, the resistance value R1 of the first feedback resistor 25 and the resistance value R2 of the second feedback resistor 26 may be set in consideration of the value of the combined resistance value R at the start of oscillation, the potential level of the input terminal G at the time of oscillation stabilization, and the feedback resistance value at the time of oscillation stabilization.

The DC cut capacitor 27 is provided between the input side of the inverter 21 and the input terminal G, and separates the signal path in a direct current manner.

The first electrostatic protection circuit 31 and the second electrostatic protection circuit 32 prevent the intrusion of surge voltage from the outside. That is, the crystal resonator 18 is externally provided to the oscillation circuit 20 via the input terminal G and the output terminal D, and thus there is a possibility that a slight leak occurs in the input terminal G and the output terminal D due to the influence of light, humidity, or the like, or the internal circuit is affected by the intrusion of a surge voltage. Therefore, by providing the first electrostatic protection circuit 31 on the signal line on the input terminal G side of the oscillation circuit 20 and providing the second electrostatic protection circuit 32 on the signal line on the output terminal D side, intrusion of surge voltage and the like can be prevented.

Each of the electrostatic protection circuits 31 and 32 includes a first semiconductor rectifying element 311 or 321, a second semiconductor rectifying element 312 or 322, and a protection resistor 313 or 323. The first semiconductor rectifying elements 311 and 321 are connected between the signal path and a predetermined constant voltage VREG, and bypass the electrostatic voltage of the first polarity intruding into the signal path toward the constant voltage VREG. The second semiconductor rectifying elements 312 and 322 are connected between the signal path and the reference potential VSS, and bypass the electrostatic voltage of the second polarity that has intruded into the signal path toward the reference potential VSS.

Accordingly, the negative and positive surge voltages entering from the outside are bypassed through the electrostatic protection circuits 31 and 32, and the entering into the oscillation circuit 20 can be prevented. The protective elements are not limited to the circuit configurations of the electrostatic protection circuits 31 and 32, and protective elements having a circuit configuration different from that of the electrostatic protection circuits 31 and 32 may be used.

Cg and Cd in fig. 3 and 4 respectively show the oscillation capacitance of the crystal oscillator 18 on the input terminal G side and the oscillation capacitance on the output terminal D side. In fig. 3 and 4, the oscillation capacitances Cg and Cd are connected to the reference potential VSS side, but may be connected to the constant voltage VREG side. The electrostatic protection circuits 31 and 32 are connected between the constant voltage VREG and the reference potential VSS, but may be connected between the power supply voltage VDD and the reference potential VSS.

Although the reference potential is set to the low-potential power supply voltage VSS in fig. 3 and 4, the high-potential power supply voltage VDD may be set to the reference potential and the low-potential power supply voltage VSS may be set to a constant voltage. Therefore, VREG in fig. 3 and 4 becomes VDD, and VSS becomes a constant voltage. In this case, the oscillation capacitors Cg, Cd may be connected to both the constant voltage VSS and the reference potential VDD.

A NAND (NAND) circuit 40 for waveform shaping is provided on the output side of the oscillator circuit 20. The NAND circuit 40 is a general NAND circuit including P-channel MOSFETs 41 and 42 and N-channel MOSFETs 43 and 44. A signal having a specific frequency, for example, 32kHz is input from the oscillation circuit 20 to the gates of the MOSFETs 41 and 43, and a predetermined control signal T, for example, a high (H) level signal T is input to the gates of the MOSFETs 42 and 44. Accordingly, the shaped clock signal is output from the NAND circuit 40.

The switch 50 is a switch that is connected in parallel with the DC cut capacitor 27 and can bypass (bypass) the DC cut capacitor 27. In the present embodiment, the switch 50 is disposed on a signal line connecting the input side of the second feedback resistor 26 and the output side of the DC cut capacitor 27, that is, the inverter 21 side.

Next, a control process of the oscillation circuit 20 realized by the control circuit 15 will be described with reference to the flowchart of fig. 5.

When power-on is performed by battery replacement or the like in step S1, the control circuit 15 short-circuits the switch 50 in step S2. By executing step S2, the oscillation circuit 20 enters the state shown in fig. 3.

Next, the control circuit 15 executes step S3, controls the constant voltage circuit 14, and applies VREG of a high potential to the oscillation circuit 20. The high potential VREG is, for example, 1.58V.

Next, the control circuit 15 executes step S4 to determine whether or not a preset time t1 has elapsed. The set time t1 is, for example, 0.5 seconds and is a time sufficient to stabilize the oscillation of the crystal resonator 18 when VREG at a high potential is applied. The set time t1 until the oscillation of the crystal transducer 18 becomes stable can be set by performing an experiment or the like. The determination as to whether or not the set time t1 has elapsed can be performed by experimentally obtaining the number of clock signals output from the NAND circuit 40 in advance from the time when the power is turned on until the set time t1 has elapsed, and measuring the set time t1 by counting the number of signals output from the NAND circuit 40.

In the case where the determination in step S4 is no, that is, in the case where the set time t1 has not elapsed, the control circuit 15 proceeds with the determination process of step S4. On the other hand, if it is determined yes in step S4, the control circuit 15 executes step S5 to control the constant voltage circuit 14 and switch to the application of VREG having a low potential. The low potential VREG is, for example, 0.91V.

Next, the control circuit 15 executes step S6 to turn off the switch 50.

By the above steps, the control process at the start of oscillation is ended, and the crystal oscillator 18 continues stable oscillation. At this time, the constant voltage circuit 14 is maintained at the low potential VREG, and the switch 50 is maintained in the off state.

The processing of step S2 and step S3 may be executed at the same timing. Similarly, the processing of step S5 and step S6 may be executed at the same timing.

Effect of the first embodiment

According to the first embodiment, when the oscillation of the oscillation circuit 20 starts, the switch 50 is short-circuited to bypass the cut-off capacitor 27, so that the self-oscillation due to the closed loop can be eliminated. Therefore, the influence of self-oscillation can be eliminated, and the start-up characteristic of the oscillation circuit 20 can be improved.

The feedback resistance value can be changed when the switch 50 is short-circuited or when it is off. That is, when the switch 50 is short-circuited, the resistance value is smaller than when it is off. Therefore, in the case of the oscillation circuit 20 in which the starting characteristic can be improved as the feedback resistance value at the start of oscillation is smaller than the feedback resistance value after the oscillation is stabilized due to the capability of the inverter 21 or the like, the starting characteristic can be further improved because the feedback resistance value can be reduced by short-circuiting the switch 50 at the start of oscillation and connecting the first feedback resistor 25 and the second feedback resistor 26 in parallel.

Since the control circuit 15 controls the constant voltage circuit 14 and applies VREG at a high potential to the oscillator circuit 20 at the start of oscillation, the start-up characteristics of the oscillator circuit 20 can be further improved. Further, since the control circuit 15 controls the constant voltage circuit 14 to switch to VREG of the low potential after the set time t1 has elapsed, the applied voltage level can be maintained low after the oscillation has stabilized, and power consumption can be reduced. Therefore, when a primary battery is used as a power source of the electronic timepiece 1, the battery life can be extended.

Since the control circuit 15 performs the voltage switching process of VREG by setting the elapse of the time t1, the process can be performed by a simple control, and the semiconductor device 10 can be prevented from becoming large. That is, when a detection circuit for detecting the oscillation state is incorporated and the voltage switching process is performed by detecting the oscillation state, the semiconductor device 10 is increased in size and cost for incorporating the detection circuit. In contrast, if the voltage switching process is performed by setting the time t1 as in the present embodiment, a detection circuit for the oscillation state is not necessary, and the semiconductor device 10 can be prevented from being increased in size.

Second embodiment

Next, a second embodiment of the present invention will be described with reference to fig. 6 to 8. In the second embodiment, the same or similar components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

As shown in fig. 6 and 7, the oscillator circuit 20B according to the second embodiment is different from the oscillator circuit 20 according to the first embodiment in that it includes a first switch 51, a second switch 52, a third switch 53, and a fourth switch 54. Since other configurations of the oscillation circuit 20B are the same as those of the oscillation circuit 20, descriptions thereof are omitted.

The first switch 51 is connected in parallel to the DC cut capacitor 27, as in the switch 50 of the first embodiment. Specifically, the first switch 51 is disposed on a signal line connecting the input side of the second feedback resistor 26 and the output side of the DC cut capacitor 27, that is, the inverter 21 side.

The second switch 52 is disposed on a signal line connecting the input side of the first feedback resistor 25 and the input side of the inverter 21, that is, between the DC cut capacitor 27 and the inverter 21.

The third switch 53 is disposed on a signal line connecting the output side of the inverter 21 between the first feedback resistor 25 and the second switch 52.

The fourth switch 54 is disposed on a signal line connecting the output sides of the first feedback resistor 25 and the second feedback resistor 26 and the output side of the inverter 21.

Next, a control process of the oscillation circuit 20B by the control circuit 15 will be described with reference to the flowchart of fig. 8. In the flowchart of fig. 8, S11, S13 to S15 except S12 and S16 are the same as S1, S3 to S5 in the flowchart of fig. 5, and therefore, the explanation thereof is simplified.

When the power supply is turned on in step S11 by a battery replacement or the like, the control circuit 15 executes step S12 to short-circuit the first switch 51 and the third switch 53 and turn off the second switch 52 and the fourth switch 54, thereby controlling the state shown in fig. 6. In this case, the first feedback resistor 25 and the second feedback resistor 26 are connected in series. Therefore, when the resistance values of the feedback resistors 25 and 26 are R1 and R2, the resistance value of the feedback resistor connected in parallel with the inverter 21 becomes R1+ R2, and when R1 is equal to R2, it becomes 2 times R1.

Next, the control circuit 15 controls the constant voltage circuit 14 in step S13, and applies VREG at a high potential to the oscillation circuit 20B.

Next, the control circuit 15 determines whether or not the preset time t1 has elapsed in step S14, and if it is determined not in step S14, the control circuit continues the determination process in step S14. On the other hand, in the case where it is determined yes in step S14, the control circuit 15 executes step S15 to control the constant voltage circuit 14 and switch to the application of VREG of the low potential.

Next, the control circuit 15 executes step S16 to turn off the first switch 51 and the third switch 53 and short-circuit the second switch 52 and the fourth switch 54, thereby controlling the state shown in fig. 7. In this case, the circuit is the same as the circuit in the first embodiment in which the switch 50 is turned off. Therefore, the feedback resistance becomes smaller than the state of fig. 6.

By the above steps, the control process at the start of oscillation is ended, and the crystal oscillator 18 continues stable oscillation. At this time, the constant voltage circuit 14 is maintained at the low potential VREG, and the oscillation circuit 20B is maintained in the state shown in fig. 7, that is, the first switch 51 and the third switch 53 are maintained in the open state, and the second switch 52 and the fourth switch 54 are maintained in the short-circuited state.

The processing in step S12 and step S13 may be executed at the same timing. Similarly, the processing of step S15 and step S16 may be executed at the same timing.

Effect of the second embodiment

According to the second embodiment, as in the first embodiment, when the oscillation of the oscillation circuit 20 starts, the first switch 51 is short-circuited to bypass the DC cut capacitor 27, so that the self-oscillation due to the closed loop can be eliminated, and the start-up characteristic of the oscillation circuit 20 can be improved.

Further, since the feedback resistor 25 and the second feedback resistor 26 can be connected in series as shown in fig. 6 at the start of oscillation, the feedback resistance value can be increased. Therefore, it is possible to provide the oscillator circuit 20B suitable for a case where the starting characteristic can be improved as the feedback resistance value at the start of oscillation is larger than the feedback resistance value after the oscillation is stabilized.

As in the first embodiment, since the control circuit 15 controls the constant voltage circuit 14 to switch the potential of VREG between when the oscillation starts and after the oscillation is stabilized, the start-up characteristics of the oscillation circuit 20 can be improved and the power consumption can be reduced. Further, as in the first embodiment, since the control circuit 15 performs the voltage switching processing of VREG in accordance with the elapse of the set time t1, the processing can be performed by simple control, and the semiconductor device 10 can be prevented from being increased in size.

Third embodiment

Next, a third embodiment of the present invention will be described with reference to fig. 9 to 11. In the third embodiment, the same or similar components as those of the second embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

As shown in fig. 9 and 10, an oscillation circuit 20C according to the third embodiment is different from an oscillation circuit 20B according to the second embodiment in that a variable resistor is used as the second feedback resistor 26C, the third switch 53 is used for switching the resistance value of the second feedback resistor 26C, and the fourth switch 54 is not provided. Since the other configuration of the oscillation circuit 20C is the same as that of the oscillation circuit 20B, the description thereof is omitted.

The first switch 51 and the second switch 52 are the same as those of the second embodiment, and therefore, the description thereof is omitted.

The third switch 53 is a switch that switches the resistance value of the second feedback resistor 26C as a variable resistor, and is set to R3> R4 if the resistance value of the second feedback resistor 26C when the third switch 53 is off is set to R3 and the resistance value of the second feedback resistor 26C when the third switch 53 is short-circuited is set to R4.

Next, a control process of the oscillation circuit 20C of the control circuit 15 will be described with reference to the flowchart of fig. 11. In the flowchart of fig. 11, S21, S23 to S25 except S22 and S26 are the same as S11, S13 to S15 in the flowchart of fig. 8, and therefore, the explanation thereof is simplified.

When the power is turned on in step S21, the control circuit 15 executes step S22 to short-circuit the first switch 51 and the third switch 53 and turn off the second switch 52, thereby controlling the state shown in fig. 9. Therefore, in the oscillation circuit 20C at the start of oscillation, the DC cut capacitor 27 is bypassed by the short circuit of the first switch 51. Further, the first feedback resistor 25 is turned off by turning off the second switch 52, and only the second feedback resistor 26C functions as a feedback resistor. Further, the resistance value of the second feedback resistor 26C is set to R4 by the short circuit of the third switch 53, and is set to a lower resistance value than R3.

Next, the control circuit 15 controls the constant voltage circuit 14 in step S23, and applies VREG at a high potential to the oscillation circuit 20C.

Next, the control circuit 15 determines whether or not the preset time t1 has elapsed in step S24, and if it is determined not in step S24, the control circuit continues the determination process in step S24. On the other hand, in the case where it is determined yes in step S24, the control circuit 15 executes step S25 to control the constant voltage circuit 14 and switch to the application of VREG of the low potential.

Next, the control circuit 15 executes step S26 to turn off the first switch 51 and the third switch 53 and short-circuit the second switch 52, thereby controlling the state shown in fig. 10. In this case, the circuit is in the same state as the switch 50 is opened in the first embodiment. Therefore, if the resistance value of the first feedback resistor 25 is R1 and R1 is R3, the feedback resistance value becomes larger than the state of fig. 9.

As a result, the control process at the start of oscillation is completed, and the crystal oscillator 18 continues to oscillate stably. At this time, the constant voltage circuit 14 is maintained at the low potential VREG, and the oscillation circuit 20C is maintained in the state shown in fig. 10, that is, the first switch 51 and the third switch 53 are maintained in the off state, and the second switch 52 is maintained in the short-circuited state.

The processing of step S22 and step S23 may be executed at the same timing. Similarly, the processing of step S25 and step S26 may be executed at the same timing.

Effect of the third embodiment

According to the third embodiment, the following effects are obtained in addition to the effects similar to the second embodiment.

As shown in fig. 9, when the oscillation starts, the first feedback resistor 25 is turned off, and the third switch 53 is further short-circuited, so that the second feedback resistor 26C is switched to a small resistance value R4. Therefore, it is possible to provide the oscillator circuit 20C suitable for a case where the starting characteristic can be improved as the feedback resistance value at the start of oscillation is made smaller than the feedback resistance value at the time of stable oscillation.

Fourth embodiment

Next, a fourth embodiment of the present invention will be described with reference to fig. 12 to 13. In the fourth embodiment, the same or similar components as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

As shown in fig. 12 and 13, the oscillation circuit 20D of the fourth embodiment is different from the oscillation circuit 20C of the third embodiment in that the third switch 53 is turned off at the start of oscillation and the third switch 53 is short-circuited when oscillation is stable after a set time t1 has elapsed, and other configurations are the same as those of the third embodiment, and therefore, the description thereof is omitted.

Although the flowchart of the fourth embodiment is not shown, only steps S22 and S26 in the flowchart of fig. 11 of the third embodiment are modified as follows. That is, in step S22, the first switch 51 is short-circuited and the second switch 52 and the third switch 53 are opened, and in step S26, the first switch 51 is opened and the second switch 52 and the third switch 53 are short-circuited.

In addition, the processing of step S22 and step S23 may be executed at the same timing as in the third embodiment. Similarly, the processing of step S25 and step S26 may be executed at the same timing.

When the oscillation of the oscillation circuit 20D starts, as shown in fig. 12, the control circuit 15 short-circuits the first switch 51 and turns off the second switch 52 and the third switch 53. Therefore, in the oscillation circuit 20D at the start of oscillation, the DC cut capacitor 27 is bypassed by the short circuit of the first switch 51. The first feedback resistor 25 is turned off by turning off the second switch 52, and only the second feedback resistor 26C functions as a feedback resistor. Further, the resistance value of the second feedback resistor 26C is set to R3 by turning off the third switch 53, and is set to a higher resistance value than R4.

After the set time t1 has elapsed from the start of oscillation, the control circuit 15 opens the first switch 51 and short-circuits the second switch 52 and the third switch 53, as shown in fig. 13. In this case, the resistance value of the second feedback resistor 26C becomes R4, and is set to a lower resistance value than R3.

Effect of the fourth embodiment

According to the fourth embodiment, the following effects are obtained in addition to the effects similar to the third embodiment.

As shown in fig. 12, at the start of oscillation, the second switch 52 is turned off to disconnect the first feedback resistor 25, and the third switch 53 is further turned off to set the second feedback resistor 26C to a resistance value R3 higher than R4. Therefore, it is possible to provide the oscillator circuit 20D suitable for a case where the starting characteristic can be improved as the feedback resistance value at the start of oscillation is larger than the feedback resistance value at the time of stable oscillation. Further, the resistance value of the second feedback resistor 26C at the time of oscillation stabilization can be set by the variable resistor.

Fifth embodiment

Next, a fifth embodiment of the present invention will be described with reference to fig. 14 and 15. In the fifth embodiment, the same or similar components as those of the second embodiment are denoted by the same reference numerals and omitted or described in brief.

As shown in fig. 14 and 15, the arrangement positions of the switches 51 to 54 of the oscillator circuit 20E according to the fifth embodiment are different from those of the oscillator circuit 20B according to the second embodiment, and the other configurations and control processes are the same as those of the second embodiment, and therefore, the description thereof is omitted.

In the oscillation circuit 20E, the same point as the oscillation circuit 20B is that the first switch 51 is provided in parallel with the DC cut capacitor 27 so that the DC cut capacitor 27 can be bypassed. Further, the same point as the oscillation circuit 20B is that the fourth switch 54 is provided between the output sides of the first and second feedback resistors 25 and 26 and the output side of the inverter 21.

On the other hand, in the oscillation circuit 20E, the second switch 52 is provided between the input side of the second feedback resistance 26 and the input side of the DC cut capacitor 27. The third switch 53 is provided between the second feedback resistor 26 and the second switch 52 and between the output side of the inverter 21.

In the fifth embodiment, the control circuit 15 performs the same control as the flowchart shown in fig. 8 of the second embodiment. That is, when the oscillation of the oscillation circuit 20E starts, as shown in fig. 14, the first switch 51 and the third switch 53 are short-circuited, and the second switch 52 and the fourth switch 54 are turned off. Therefore, in the oscillation circuit 20E at the start of oscillation, the DC cut capacitor 27 is bypassed by short-circuiting the first switch 51. Since the third switch 53 is short-circuited and the second switch 52 and the fourth switch 54 are open, the first feedback resistor 25 and the second feedback resistor 26 are connected in series between the input side and the output side of the inverter 21, and the feedback resistance value is increased to R1+ R2.

After the set time t1 has elapsed from the start of oscillation, that is, when the oscillation is stable, the control circuit 15 turns off the first switch 51 and the third switch 53 and short-circuits the second switch 52 and the fourth switch 54, as shown in fig. 15. In this case, the circuit is in the same state as the switch 50 is opened in the first embodiment. Therefore, the feedback resistance becomes smaller than the state of fig. 14.

The processing of step S12 and step S13 may be executed at the same timing as in the second embodiment. Similarly, the processing of step S15 and step S16 may be executed at the same timing.

Effect of the fifth embodiment

According to the fifth embodiment, the same effects as those of the second embodiment can be obtained.

Other embodiments

The present invention is not limited to the above embodiments, and modifications, improvements, and the like within a range that can achieve the object of the present invention are also included in the embodiments of the present invention.

First modification

For example, although the second switch 52 is disposed between the DC cut capacitor 27 and the inverter 21 and the input side of the first feedback resistor 25 in the third embodiment, the second switch 52 may be disposed on the output side of the first feedback resistor 25 as in the oscillation circuit 20F shown in fig. 16 and 17. That is, the second switch 52 for disconnecting the first feedback resistor 25 at the start of oscillation may be connected in series with the first feedback resistor 25. Therefore, as shown in fig. 9 and 10, the second switch 52 may be connected in series with the input side of the first feedback resistor 25, or as shown in fig. 16 and 17, the second switch 52 may be connected in series with the output side of the first feedback resistor 25. That is, the second switch 52 connects the first feedback resistor 25 in parallel with the inverter 21 when short-circuited, and disconnects the first feedback resistor 25 when open, thereby preventing the feedback resistor from functioning.

According to the oscillation circuit 20F of the first modification example, as in the third embodiment, at the start of oscillation, the first feedback resistor 25 is turned off as shown in fig. 16, and the third switch 53 is further short-circuited, so that the second feedback resistor 26C is switched to the small resistance value R4. Therefore, it is possible to provide the oscillator circuit 20F suitable for the case where the starting characteristic can be improved as the feedback resistance value at the start of oscillation is made smaller than the feedback resistance value at the time of stable oscillation.

In the first modification, the third switch 53 may be controlled in the reverse order of the short-circuit and the open order. That is, when the oscillation of the oscillation circuit 20F starts, the first switch 51 may be short-circuited to turn off the second switch 52 and the third switch 53, and when the oscillation is stable, the first switch 51 may be turned off to short-circuit the second switch 52 and the third switch 53.

In this case, as in the fourth embodiment, at the start of oscillation, the second switch 52 is turned off to turn off the first feedback resistor 25, and the third switch 53 is further turned off to set the second feedback resistor 26C to a resistance value R3 higher than R4. Therefore, it is possible to provide an oscillator circuit suitable for a case where the starting characteristics can be improved as the feedback resistance value at the start of oscillation is set to be higher than the resistance value R3 of R4.

Second modification example

As in the oscillation circuit 20G shown in fig. 18 and 19, the first feedback resistor 25C may be formed of a variable resistor, and the third switch 53 may be provided to switch the variable resistance value of the first feedback resistor 25C while connecting the second switch 52 in series with the second feedback resistor 26. When the resistance value of the first feedback resistor 25C when the third switch 53 is turned off is R5 and the resistance value of the first feedback resistor 25C when the third switch 53 is short-circuited is R6, R5 > R6 is set.

When the oscillation of the oscillation circuit 20G starts, as shown in fig. 18, the control circuit 15 short-circuits the first switch 51 and turns off the second switch 52 and the third switch 53. When the oscillation of the oscillation circuit 20G is stable, the control circuit 15 turns off the first switch 51 and short-circuits the second switch 52 and the third switch 53, as shown in fig. 19.

According to the oscillation circuit 20G of the second modification, when oscillation is stable, as shown in fig. 19, the first feedback resistor 25C can be adjusted to the variable resistance value R6, and thus can be set in accordance with the capability of the inverter 21.

Third modification example

In the second modification, as in the oscillation circuit 20H shown in fig. 20 and 21, the position of the second switch 52 connected in series with the second feedback resistor 26 may be connected to the output terminal D side of the second feedback resistor 26. The third modification also can obtain the same operational effects as the second modification.

In the second modification and the third modification, the order of short-circuiting and opening of the third switch 53 may be controlled in a reverse manner. That is, when the oscillation of the oscillation circuits 20G and 20H starts, the first switch 51 and the third switch 53 are short-circuited and the second switch 52 is opened, and when the oscillation is stable, the first switch 51 and the third switch 53 are opened and the second switch 52 is short-circuited.

Although the oscillation circuits 20, 20B, 20C, 20D, 20E, 20F, 20G, and 20H according to the above embodiments are incorporated in the movement of the electronic timepiece 1, the present invention can be widely applied to various electronic devices incorporating an oscillation circuit. In particular, the semiconductor device 10 having the oscillation circuits 20, 20B, 20C, 20D, 20E, 20F, 20G, and 20H can be configured and power consumption can be reduced, and therefore, the semiconductor device is suitable for a small-sized battery-driven electronic apparatus.

In the above embodiments, the constant voltage circuit 14 is controlled by the control circuit 15, and VREG of a higher voltage is applied at the start of oscillation and VREG of a lower voltage than the higher voltage is applied at the stabilization of oscillation. Specifically, for example, in the first embodiment, the predetermined VREG may be applied in step S3 without performing the step S5. In particular, in the present invention, since the start-up characteristic is improved by changing the feedback resistance value of the inverter 21 at the start of oscillation and at the time of stable oscillation, oscillation can be performed normally even if the voltage V of VREG at the start of oscillation is set to the same level as that at the time of stable oscillation.

The oscillation circuit is not limited to the circuit of the above-described embodiment, and may be provided with a switch for bypassing the DC cut capacitor 27 at the start of oscillation. Preferably, the oscillation circuit includes a switch capable of switching the feedback resistance value between when the oscillation starts and when the oscillation is stable.

In the above-described embodiments and modifications, the third switch 53 provided in the feedback resistors 26C and 25C as variable resistors is connected to the input side of the feedback resistors 26C and 25C, but may be connected to the output side of the feedback resistors 26C and 25C.

Description of the symbols

1 … electronic timepiece; 10 … semiconductor device; a divide-by-11 … circuit; 12 … frequency divider circuit; 13 … driver circuit; 14 … constant voltage circuit; 15 … control circuitry; 18 … quartz crystal transducer; 20. 20B, 20C, 20D, 20E, 20F, 20G, 20H … oscillating circuit; 21 … inverter; 25 … a first feedback resistance; 26. 26C … second feedback resistance; 27 … DC cutoff capacitor; 31 … a first electrostatic protection circuit; 32 … second electrostatic protection circuit; 40 … NAND circuit; a 50 … switch; 51 … a first switch; 52 … second switch; 53 … third switch; 54 … a fourth switch; a G … input terminal; d … output terminal.