JP2007096947A - Piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a reduction of a startup time for all piezoelectric oscillators. <P>SOLUTION: A piezoelectric oscillator is provided with a piezoelectric oscillating circuit with a piezoelectric vibrator, a switch circuit for connecting an oscillation loop circuit of the piezoelectric oscillating circuit to a supply voltage line, and a control circuit for controlling an ON/OFF operation of the switch circuit. When an amplitude level of an excitation signal of the piezoelectric vibrator is within a maximum value ±0.1 λ after applying the supply voltage, the switch circuit performs the ON operation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric oscillator, and more particularly to a piezoelectric oscillator that shortens a startup time from a non-operation state to an oscillation operation state.

Cellular phones are designed to reduce power consumption by intermittently operating a crystal oscillator that is used as a reference transmission source so that the battery can be used continuously for a long time.
In such a crystal oscillator that operates intermittently, it is desired that the startup time required from the start of driving to the oscillation of a desired output signal is short, and the configuration as shown in WO 02/007302 There is something.
FIG. 11 shows a circuit diagram of the crystal oscillator disclosed in the prior art.
A crystal oscillator 100 shown in FIG. 1 includes a Colpitts-type crystal oscillation circuit 101 and a fast start-up circuit 102.
In the crystal oscillation circuit 101, the other end of the crystal resonator 105, one end of which is connected to the ground via the capacitor 104, is connected to the base of the oscillation transistor 103, and the capacitor 106 and the capacitor 107 are connected between the base and the ground. A series circuit is inserted and connected, and the connection midpoint of this series circuit and the emitter of the transistor 103 are connected, and an emitter resistor 108 is connected between the emitter and the ground.
Further, the transistor 109 and the transistor 103 for constituting the grounded base amplifier circuit are cascode-connected, and a capacitor 110 is inserted and connected between the base of the transistor 109 and the ground, and the collector of the transistor 109 and the power supply voltage Vcc line are connected. A collector resistor 111 is inserted and connected between them, a constant current circuit 112 is inserted and connected between the base of the transistor 109 and the power supply voltage Vcc line, and the transistor 103 and the transistor 109 are connected to each other by a circuit network including the resistor 113 and the resistor 114. A configuration in which a base bias is appropriately applied is provided.
The fast start-up circuit 102 connects the emitter of the PNP transistor 115 and the power supply voltage Vcc line via the resistor 116, and connects the base of the transistor 115 and the power supply voltage Vcc line via the capacitor 117. The base and the ground are connected via a capacitor 118, and the collector of the transistor 115 and the other end of the crystal resonator 105 are connected via a series circuit including a resistor 119 and a resistor 120.
The base of the transistor 121 is connected to the connection midpoint of the series circuit composed of the resistors 119 and 120, the collector of the transistor 121 is connected to the power supply voltage Vcc line via the resistor 122, and the transistors 115 and 121 are connected to the Darlington. In addition to being connected, the emitter of the transistor 121 is connected to the other end of the crystal unit 105.
In the crystal oscillator having such a configuration, the transistor 115 is turned on by the charge of the capacitor 117 generated after application of the power supply voltage Vcc, so that the transistor 121 is turned on and the power supply voltage is supplied to the other end of the crystal resonator 105. It operates so as to apply Vcc as a startup promoting voltage.
In the crystal oscillator 100, since the crystal resonator 105 is strongly excited by receiving the activation promoting voltage immediately after the power supply voltage Vcc is applied, the time until the level of the output signal reaches a desired level is short. It will be something.
In this case, in order to start the crystal oscillator 100 efficiently and at high speed, the crystal oscillator 105 has a sufficiently high potential to vigorously excite, and even a start-up promoting voltage having a steep rise characteristic is applied to the crystal oscillator 105. It was thought that it should be done.
Therefore, only the time required for the power supply voltage Vcc to reach the peak value is defined as the timing at which the transistor 115 is turned on, and the capacitance ratio between the capacitors 117 and 118 is adjusted so that the predetermined time is obtained. It was thought that it should be done.

However, the conventional crystal oscillator in which the timing for applying the activation promoting voltage to the crystal resonator is set to be when the power supply voltage Vcc reaches the peak voltage, the start-up voltage is sufficiently fast depending on the difference in the frequency of the crystal resonator 105. There was a case not to.
WO02 / 07302 Publication

  The problem to be solved is to provide a piezoelectric oscillator that shortens the startup time from the non-operating state to the oscillating operating state.

  The present invention is a piezoelectric oscillator provided with a high-speed start-up circuit. When one period of the excitation signal of the piezoelectric vibrator is represented by λ, supply of a start-up promotion voltage supplied from the high-speed start-up circuit to the piezoelectric vibrator Timing is set within the range of (2 × λ × (2 × n−1)) / 5 to (3 × λ × (2 × n−1)) / 5 from the point of application of the power supply voltage (n is a positive integer) It is characterized by that.

  The piezoelectric oscillator according to the present invention is based on the amplitude level of the excitation signal of the piezoelectric vibrator based on the application timing of the activation promoting voltage supplied from the high speed starting circuit to the piezoelectric vibrator or the oscillation loop circuit. This has the advantage that the startup time can be shortened.

FIG. 1 is a circuit diagram for explaining a piezoelectric oscillator according to the present invention.
The piezoelectric oscillator 1 shown in the figure includes, for example, a Colpitts-type crystal oscillation circuit 2 and a fast startup circuit 3.
In the crystal oscillation circuit 2, the other end of a crystal resonator 6 having one end connected to the ground via a capacitor 5 is connected to the base of the oscillation transistor 4, and the capacitor 7 and the capacitor 8 are connected between the base and the ground. A series circuit is inserted and connected, and the connection midpoint of this series circuit and the emitter of the transistor 4 are connected, and an emitter resistor 9 is connected between the emitter and the ground.
Further, the transistor 10 and the transistor 4 for constituting the grounded base amplification circuit are cascode-connected, and the capacitor 11 is inserted and connected between the base of the transistor 10 and the ground, and the collector of the transistor 10 and the power supply voltage Vcc are connected. A resistor 12 is inserted and connected, a constant current circuit 13 is inserted and connected between the base of the transistor 10 and the power supply voltage Vcc line, and the base of the transistor 4 and the transistor 10 is formed by a circuit network including the resistor 14 and the resistor 15. A configuration in which a bias is appropriately applied is provided.
The fast start-up circuit 3 is a so-called switch circuit, in which a resistor 17 is inserted and connected between the collector of the transistor 16 and the power supply voltage Vcc line, and a capacitor 18 is inserted between the base of the transistor 16 and the power supply voltage Vcc line. In addition to being connected, a structure is provided in which a diode 19 is inserted in the reverse direction between the base of the transistor 16 and the ground.
Then, when the power supply voltage Vcc is applied, the piezoelectric oscillator 1 having such a configuration starts to charge the capacitor 18 that functions as an ON / OFF operation control circuit (ON / OFF operation control element) of the switch circuit. Accordingly, since the base current is supplied to the transistor 16, the switch circuit including the transistor 16 is turned on so that the power supply voltage Vcc line and the other end of the crystal resonator 6 are electrically connected.
In the case of the piezoelectric oscillator 1 shown in FIG. 1, by selecting the capacitor C18 having a desired time constant, the timing at which the transistor 16 is turned on can be delayed by a predetermined time from the time when the power supply voltage Vcc is applied. Is possible.
A feature of the present invention is that the timing of applying the activation promoting voltage to the crystal resonator 6 or the oscillation loop circuit is set when the amplitude level of the excitation signal of the crystal resonator 6 is almost at the peak value.
That is, when one period of the excitation signal of the crystal unit 6 in the piezoelectric oscillator 1 is expressed as λ, the amplitude of the excitation signal of the crystal unit 6 becomes a maximum value within a range of 0.1λ before and after the maximum value. Desirably, when the amplitude reaches a maximum value, or as another expression, when the power supply voltage Vcc is applied, the level of the excitation signal of the crystal resonator 6 is generally a minimum value, so that the power supply voltage Vcc is applied. When the cycle is within the range of (2 × λ × (2 × n−1)) / 5) to (3 × λ × (2 × n−1)) / 5 from the time point, the cycle is more preferably (λ × When the transistor 16 is turned on at (2 × n−1)) / 2, the power supply voltage Vcc is applied to the crystal resonator 6 or the oscillation loop circuit as the activation promoting voltage. Can be smoothly promoted (n is a positive integer).
Since the piezoelectric oscillator 1 can be started at the earliest and smoothly at high speed, the period of the piezoelectric oscillator 1 is in the range of (2 × λ) / 5 to (3 × λ) / 5 from the time when the power supply voltage Vcc is applied. The high-speed start-up circuit 3 functions so as to apply the start-up promoting voltage to the crystal resonator 6 or the oscillation loop circuit at λ / 2.
This time setting can be realized by selecting a capacitor C18 having a desired time constant.
Hereinafter, it will be described based on simulation results that the startup characteristics of the piezoelectric oscillator 1 according to the present invention are increased in speed.
2 to 5 show the relationship between the application timing of the activation promoting voltage to the crystal resonator 6 and the activation characteristics of the piezoelectric oscillator 1, and FIG. FIG. 3 shows the excitation signal of the crystal resonator 6 when the excitation signal of the crystal resonator 6 reaches 1λ with reference to the application time of the power supply voltage Vcc. 5 reaches 1.5λ with respect to the application time point of the power supply voltage Vcc, and FIG. 5 shows a circuit 3 for fast startup when the excitation signal of the crystal unit 6 reaches 0.5λ with reference to the application time point of the power supply voltage Vcc. These are the results of simulating the start-up characteristics when the start-up promoting voltage is applied to the crystal resonator 6.
The startup promoting voltage is a voltage at the time when the power supply voltage Vcc increases with application and reaches a peak voltage value.
The excitation signal of the crystal resonator 6 starts from the minimum amplitude level when the power supply voltage Vcc is applied. Therefore, when the power supply voltage Vcc is applied, the excitation signal of the crystal resonator 6 reaches 2λ. The amplitude level is a local minimum.
At this time, when the activation promoting voltage P is applied to the crystal resonator 6, as shown in FIG. 2, immediately after the activation promoting voltage P is applied, the crystal resonator 6 is in a state where the excitation operation is stopped or a sufficient excitation operation does not occur. I understand that
Further, even when the excitation signal of the crystal unit 6 reaches λ, the amplitude level of the crystal unit 6 is a minimum value. When the activation promoting voltage P is applied to the crystal unit 6 at this time, as shown in FIG. It can be understood that immediately after the activation promotion voltage P is applied, the crystal unit 6 is in a state where the excitation operation is stopped or a sufficient excitation operation does not occur.
On the other hand, when the excitation signal of the crystal resonator 6 reaches 1.5λ << (λ × (2 × n-1)) / 2, when n = 2}, the excitation level of the crystal resonator 6 is a maximum value. At this time, if the activation promoting voltage P is applied to the crystal resonator 6, as shown in FIG. 4, the crystal resonator 6 continues its excitation operation even after the activation promoting voltage P is applied, and its amplitude level is high. It can be understood that it becomes a state.
Furthermore, when the excitation signal of the crystal unit 6 reaches 0.5λ << (λ × (2 × n-1)) / 2, when n = 1}, the excitation level of the crystal unit 6 is also the maximum value. At this time, when the activation promoting voltage P is applied to the crystal resonator 6, as shown in FIG. 5, the crystal resonator 6 is strongly excited as compared with the case shown in FIG.
Since there is no condition for the excitation signal of the crystal resonator 6 to reach the maximum value at a time earlier than 0.5λ, the activation promoting voltage at the time of 0.5λ (at the first peak amplitude level). The piezoelectric oscillator 1 can be activated at the highest speed when is applied.
Note that, depending on the error in the circuit setting conditions, it may not always be possible to apply the startup promoting voltage at the time of 0.5λ, but the crystal when the startup promoting voltage is applied at the ideal time of 0.5λ. When the amplitude level of the vibrator 6 is used as a reference, the start-up characteristic of the piezoelectric oscillator 1 is not extremely bad as long as the start-up characteristic has a level attenuation of about 30% or less.
Therefore, FIG. 6 shows the result of a simulation of the application timing of the start-up promoting voltage that can obtain the start-up characteristic with the excitation level attenuated by 30%.
As shown in the figure, to obtain the amplitude level attenuated by 30% with respect to the amplitude level of the excitation signal when the activation promoting voltage P is applied when the excitation signal of the crystal resonator 6 becomes 0.5λ. It has been found that it is sufficient to apply a startup promoting voltage to the crystal resonator or the oscillation loop circuit at a time of about 0.6λ.
Even at the time of about 0.4λ, since the amplitude level is equal to 0.6λ, the same starting characteristics can be obtained.
Therefore, the condition for obtaining a startup characteristic that is almost inferior to the case where the startup acceleration voltage is applied to the maximum value of the excitation signal of the crystal unit 6 is ±± with respect to the maximum value of the excitation signal of the crystal unit 6. 0.1λ, that is, within a range of (2 × λ × (2 × n−1)) / 5) to (3 × λ × (2 × n−1)) / 5 (where n = positive In addition, the condition for obtaining a start characteristic almost inferior to the timing 0.5λ at which the best start characteristic is obtained is in the range of (2 × λ) / 5 to (3 × λ) / 5. Is within.
As described above, the feature of the present invention is that the timing for applying the activation promoting voltage, which is the peak of the power supply voltage Vcc, is set when the excitation signal of the crystal unit 6 reaches the maximum value of the amplitude level. When constructing a piezoelectric oscillator, it is necessary to strictly set the rise time of the start-up promotion voltage and the ON operation time of the switch circuit. To achieve this, circuit adjustment can be performed with high accuracy. A piezoelectric oscillator is desirable.
Therefore, the configuration and the like of a piezoelectric oscillator that can perform circuit adjustment with high accuracy will be described below.
The configuration of the crystal oscillation circuit 2 is the same as that shown in FIG.
In the piezoelectric oscillator 1 shown in FIG. 7, the fast start circuit 3 has a resistor 17 inserted and connected between the collector of the transistor 16 and the power supply Vcc line, and the base of the transistor 20 is connected to the base of the transistor 16. A resistor 21 is inserted and connected between the collector of the transistor 20 and the power supply voltage Vcc line, a resistor 22 is inserted and connected between the base and emitter of the transistor 20, and the base of the transistor 20 and the emitter of the transistor 23 are connected via the resistor 24. In this configuration, the base of the transistor 23 is connected to the connection midpoint of the capacitor 18 and the diode 19.
In the case of the piezoelectric oscillator 1 having such a configuration, in order to adjust the setting of the timing for applying the activation promoting voltage, the time constants of the capacitor 18 and the resistor 24 may be set to desired values. Compared with the case where it does, since there are two adjustment parts, a high adjustment precision is obtained.
The piezoelectric oscillator 1 shown in FIG. 8 includes a PNP-type transistor 16 in the high-speed startup circuit 3, and the collector of the transistor 25 is connected to the base of the transistor 16, and the base of the transistor 16 and the power supply voltage Vcc line are connected. A resistor 26 is inserted and connected, a resistor 27 is inserted and connected between the emitter of the transistor 25 and the ground, a capacitor 18 is inserted and connected between the base of the transistor 25 and the power supply voltage Vcc line, and the base of the transistor 25 is connected. The diode 19 is connected in the reverse direction between the ground and the ground.
In the case of the piezoelectric oscillator 1 having such a configuration, in order to adjust the setting of the timing for applying the activation promoting voltage, the time constants of the capacitor 18, the resistor 26, and the resistor 27 may be set to desired values. Compared with the case where the adjustment is performed only by the adjustment, since there are three adjustment portions, a high adjustment accuracy can be obtained.
In the piezoelectric oscillator 1 shown in FIG. 9, the fast start circuit 3 connects the emitter of the transistor 28 and the other end of the crystal resonator 6 via a series circuit including a resistor 29 and a resistor 30. When the base of the transistor 16 is connected to the connection midpoint, the collector of the transistor 16 is connected to the power supply voltage Vcc line via the resistor 17, the emitter of the transistor 16 is connected to the other end of the crystal unit 6, and the transistor 18 A capacitor 18 is inserted and connected between the base and the power supply voltage Vcc line, and a diode 19 is reversely connected between the base of the transistor 18 and the ground.
Even in the piezoelectric oscillator 1 having such a configuration, the setting of the timing for applying the activation promoting voltage can be adjusted by setting the time constants of the capacitor 18, the resistor 17, and the resistor 29 to desired values. Compared with the case where adjustment is performed only with the capacity 18, etc., a high adjustment system can be obtained because there are three adjustment sections.
Further, as shown in FIG. 10, the crystal oscillation circuit 2 and the fast startup circuit 3 are configured as separate power sources.
In such a configuration, the timing of applying the power supply Vcc ′ itself of the fast start-up circuit 3 can be delayed from the timing of applying the power supply voltage Vcc of the crystal oscillation circuit 2, so that the timing of applying the start-up promoting voltage is set. In the case of setting, it is only necessary to adjust / set the input timing of the power supply voltage Vcc ′ in addition to the adjustment of the time constants of the capacitor 18, the resistor 17, and the resistor 29, so that higher adjustment accuracy can be obtained.

It is a circuit diagram which shows one Example of the piezoelectric oscillator based on this invention. Relationship between the timing of applying the acceleration voltage and the startup characteristics of the piezoelectric oscillator Relationship between the timing of applying the acceleration voltage and the startup characteristics of the piezoelectric oscillator Relationship between the timing of applying the acceleration voltage and the startup characteristics of the piezoelectric oscillator Relationship between the timing of applying the acceleration voltage and the startup characteristics of the piezoelectric oscillator Simulation results of application timing of startup acceleration voltage It is a circuit diagram which shows the other Example of the piezoelectric oscillator based on this invention. It is a circuit diagram which shows the other Example of the piezoelectric oscillator based on this invention. It is a circuit diagram which shows the other Example of the piezoelectric oscillator based on this invention. It is a circuit diagram which shows the other Example of the piezoelectric oscillator based on this invention. It is a circuit diagram for demonstrating the conventional piezoelectric oscillator.

Explanation of symbols

1 piezoelectric oscillator, 2 crystal oscillation circuit, 3 high-speed startup circuit, 4 transistor, 5 capacitor, 6 crystal resonator, 7 capacitor, 8 capacitor, 9 resistor, 10 transistor, 11 capacitor, 12 resistor, 13 constant current circuit, 14 Resistor, 15 resistor, 16 transistor, 17 resistor, 18 capacitor, 19 diode, 20 transistor, 21 resistor, 22 resistor, 23 transistor, 24 resistor, 25 transistor, 26 resistor, 27 resistor, 28 transistor, 29 resistor, 30 resistor

Claims (5)

  A piezoelectric oscillation circuit having a piezoelectric vibrator, a switch circuit for connecting an oscillation loop circuit of the piezoelectric oscillation circuit and a power supply voltage line, and a control circuit for controlling ON / OFF operation of the switch circuit The piezoelectric oscillator is characterized in that, after the power supply voltage is applied, the switch circuit is turned on when the amplitude level of the excitation signal of the piezoelectric vibrator is within the range of the maximum value ± 0.1λ.   A piezoelectric oscillation circuit having a piezoelectric vibrator, a switch circuit for connecting an oscillation loop circuit of the piezoelectric oscillation circuit and a power supply voltage line, and a control circuit for controlling ON / OFF operation of the switch circuit The piezoelectric oscillator is characterized in that, after the power supply voltage is applied, the switch circuit is turned on when the amplitude level of the excitation signal of the piezoelectric vibrator is a maximum value.   A piezoelectric oscillation circuit having a piezoelectric vibrator, a switch circuit for connecting an oscillation loop circuit of the piezoelectric oscillation circuit and a power supply voltage line, and a control circuit for controlling ON / OFF operation of the switch circuit The switch circuit is turned on when the amplitude level of the excitation signal of the piezoelectric vibrator is in the range of (2 × λ) / 5 to (3 × λ) / 5 from the time when the power supply voltage is applied. A piezoelectric oscillator characterized by that.   A piezoelectric oscillation circuit having a piezoelectric vibrator, a switch circuit for connecting an oscillation loop circuit of the piezoelectric oscillation circuit and a power supply voltage line, and a control circuit for controlling ON / OFF operation of the switch circuit The piezoelectric oscillator is characterized in that the switch circuit is turned on when the amplitude level of the excitation signal of the piezoelectric vibrator is λ / 2 from the time when the power supply voltage is applied. The switch circuit is a transistor, the control circuit is a capacitor connected between a base of the transistor and the power supply voltage line, and the switch circuit has a base current in the transistor by a charge current of the capacitor. 5. The piezoelectric oscillator according to claim 1, wherein the piezoelectric oscillator is supplied and is turned on, and the timing of turning on is set by a time constant of the capacitance.

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