JP5216674B2 - Crystal resonator quality evaluation method - Google Patents

Description

The present invention relates to a quality judgment how the crystal oscillator, in particular, a crystal oscillator to be determined, and the IC circuit for oscillating this is sealed in a package so that wiring connecting each other is not exposed to the outside about the quality determination how the crystal oscillator in a crystal oscillator formed by.

  In a conventional crystal oscillator, a crystal resonator sealed in a package and a wiring connecting an IC circuit that oscillates the crystal resonator are exposed outside the package (hereinafter referred to as an exposed type for convenience). ) And those that are not exposed to the outside of the package (hereinafter referred to as non-exposed type for convenience). In the case of the exposed type, after sealing the crystal resonator and the IC circuit in the package, the characteristics of the crystal resonator are inspected using the electrode exposed to the outside, and the quality is determined. On the other hand, in the case of the non-exposed type, after the crystal unit and the IC circuit are sealed in the package, the characteristics of the crystal unit cannot be inspected. These characteristics are inspected and the quality is judged.

  The exposed crystal oscillator has the disadvantage of causing electrostatic breakdown due to the exposed wiring. Also, as the package is downsized, it has become difficult to perform inspection using the electrode exposed to the outside. Therefore, there is a demand for a non-exposed crystal oscillator, and there is a demand for realizing a quality determination method for a crystal resonator in a non-exposed crystal oscillator in a sealed state in the package.

  However, conventionally, there is no known method for determining the quality of a crystal resonator in a non-exposed crystal oscillator that is sealed in a package. On the other hand, as a pass / fail determination method other than the method of directly inspecting the characteristics of a crystal resonator, which is performed before sealing in a conventionally known package, an AGC amplifier circuit whose amplification factor changes according to a DC input voltage For example, the maximum value of the DC input voltage is measured when the crystal oscillation circuit starts to oscillate by increasing the DC input voltage. There is a method of judging the quality of a crystal resonator according to the measured maximum value (Patent Document 1).

JP 2001-242209 A

The above determination method uses a special determination circuit called a crystal oscillation circuit having an AGC amplifier circuit whose amplification factor changes according to a DC input voltage and to which a crystal resonator to be determined is connected. Since the IC circuit to be oscillated is a pass / fail determination method without sealing in the package, the crystal resonator is connected to an IC circuit different from that used for determination when the package is sealed. The operation is not necessarily the same as that at the time of determination, and the reliability is not high. Further, since the determination method is not performed in a package sealed state, it cannot meet the above-mentioned demand. Further, the determination crystal oscillation circuit itself is sealed in a package. It is practically impossible to use as a non-exposure type crystal oscillator. The present invention has such has been made in view of the circumstances, in fact non-exposed type crystal oscillator in the state sealed in a package, aims to provide a decision how that can determine the quality of the crystal oscillator And

In general, it is known that oscillation does not occur when the series resonance resistance value of the crystal resonator is larger than the negative resistance value of the IC circuit that oscillates the crystal resonator. Therefore, the negative resistance value when the oscillation is stopped or when the oscillation is started can be regarded as the series resonance resistance value of the crystal resonator. The negative resistance (−RL) is −RL≈−gm / (ω ² ·, where ω is the angular frequency of the oscillation frequency, gm is the mutual conductance of the inverter, and Cd and Cg are load capacitance values. Cd · Cg), a negative resistance (−RL) value of a desired value can be set when designing an IC circuit. Furthermore, although the oscillation state can be changed by changing the negative resistance value, it is known that the negative resistance value changes depending on the configuration of the IC circuit. That is, the value of the negative resistance (−RL) is changed by changing the mutual conductance gm of the above-described formula and the capacitance values Cd and Cg of the load capacitance. The present invention, by applying these known matters are how to determine the quality of the crystal oscillator in a state where the crystal oscillator of the non-exposed type is actually sealed in a package.

  In the crystal resonator quality determination method according to the present invention, a determination target crystal resonator and an IC circuit that oscillates the crystal resonator are sealed in a package so that wirings that connect each other are not exposed to the outside. A crystal oscillator having a terminal for inputting an external signal and having means for changing the negative resistance value of the IC circuit by an external control signal is used to monitor the oscillation output while changing the negative resistance value, and to oscillate. The series resonance resistance value of the crystal resonator is obtained from the negative resistance value at the time of stopping and / or starting of oscillation, and the relationship between the series resonance resistance value and the negative resistance value at the time of designing the IC circuit is obtained. Based on this, the quality of the crystal resonator is judged. More specifically, if the negative resistance value is 5 times or more of the series resonance resistance value, it is determined as a non-defective product, and if it does not reach 5 times, it is determined as a defective product. The means for changing the negative resistance value of the IC circuit may be a means for changing the supply voltage to the amplification section of the IC circuit, a means for changing the amplification degree of the amplification section of the IC circuit, It is preferable to configure with means for changing the capacity value of the load capacity.

  According to the quality determination method for a crystal resonator according to the present invention, the determination target crystal resonator, an IC circuit that oscillates the crystal resonator, and the wiring that connects them are all sealed in a package. Since the quality determination of the crystal resonator is performed, it is possible to accurately determine the quality of the crystal resonator in the commercialized state.

1 is a circuit diagram showing a first embodiment of the present invention. The longitudinal cross-sectional view which shows 2nd Embodiment of this invention. The circuit diagram which shows 3rd Embodiment of this invention.

Will be described below with reference to preferred embodiments of the quality determination how the crystal oscillator according to the present invention in the accompanying drawings. Here, FIG. 1 is a circuit diagram in the case where the means for changing the negative resistance value of the IC circuit is a means for changing the supply voltage to the amplifier of the IC circuit, and FIG. FIG. 3 is a circuit diagram in a case where the means for changing the negative resistance value of the IC circuit according to the embodiment is a means for changing the amplification degree of the amplification unit of the IC circuit, and FIG. 3 is a negative diagram of the IC circuit according to the third embodiment. FIG. 6 is a circuit diagram when the means for changing the resistance value is a means for changing the capacitance value of the load capacitance of the IC circuit.

  First, the first embodiment will be described. As shown in FIG. 1, a crystal oscillator 10 includes a crystal resonator 1 that generates a voltage that oscillates at a specific frequency to be determined, and an IC circuit 2 that oscillates the crystal resonator 1. Has an input terminal IN. The IC circuit 2 is connected in parallel with the crystal resonator 1 and an inverter 3 which is an amplifying unit for amplifying the oscillation voltage, a feedback resistor 4 connected in parallel to the inverter 3, and an input terminal of the inverter 3 One electrode is connected to the output terminal, and the other electrode includes load capacitors 5 and 6 that are grounded.

  A power supply voltage is supplied to the inverter 3 from the voltage regulator 7, and the voltage supply amount of the voltage regulator 7 is controlled by a voltage controller 8 to which an external control signal is input via an input terminal IN. The voltage regulator 7 and the voltage controller 8 constitute means for changing the supply voltage to the inverter 3 as an amplifying unit, which is means for changing the negative resistance value. Although not shown, the crystal oscillator 10 is entirely sealed in a ceramic package.

  Generally, when the power supply voltage of the inverter 3 decreases, the mutual conductance decreases and the negative resistance value decreases. On the other hand, when the power supply voltage of the inverter 3 increases, the mutual conductance increases and the negative resistance value decreases. It is known to grow. In general, since oscillation does not occur when the series resonance resistance value of the crystal resonator 1 is larger than the negative resistance value, the negative resistance value when the oscillation is stopped is approximately equal to the series resonance resistance value of the crystal resonator 1. Can be considered. Further, the negative resistance value can be obtained at the time of designing the IC circuit 2, and can be set to a desired value by the circuit design. In the present embodiment, the quality of the crystal unit 1 is determined based on these known matters.

  Specifically, the crystal oscillator 10 is oscillated and its oscillation output is monitored with an oscilloscope or the like, while the voltage supply amount to the inverter 3 by the voltage regulator 7 is controlled via the voltage controller 8 by an external control signal. Then, the negative resistance value of the IC circuit 2 is adjusted and gradually decreased. If the negative resistance value at the time of stopping the oscillation is the series resonance resistance value of the crystal resonator 1 and the negative resistance value set at the time of designing the IC circuit 2 is 5 times or more of the series resonance resistance value, The crystal unit 1 is determined to be a non-defective product if it does not reach 5 times. This criterion for pass / fail judgment is confirmed by experiments.

  When using the crystal oscillator 10 after the pass / fail judgment of the crystal resonator 1, the voltage controller 8 is controlled by an external control signal so that the voltage supply amount to the inverter 3 by the voltage regulator 7 becomes a set value when the IC circuit 2 is designed. To do.

  Next, a second embodiment will be described. As shown in FIG. 2, the crystal oscillator 20 includes a crystal resonator 11 that generates a voltage that oscillates at a specific frequency to be determined, and an IC circuit 12 that oscillates the crystal resonator 11, and an external control signal. Has an input terminal IN. The IC circuit 12 is connected in parallel with each of the crystal units 11, and four inverters 13, 14, 15, and 16 that are amplification units that amplify the oscillation voltage, and these inverters 13, 14, 15, and 16 are connected in parallel. Each of the inverters 13, 14, 15 and 16 has a connected feedback resistor 17 and one of the electrodes connected to the input and output terminals of each of the inverters 13, 14, 15 and 16, and the other electrode has a grounded load capacitor 18 and 19. Yes. Further, switching elements SW1, SW2 and SW3 made of transistors or the like are provided on the input sides of the inverters 14, 15 and 16 except the inverter 13, respectively. A control signal is input to the switching elements SW1, SW2 and SW3 from the input terminal IN via the switch selection circuit 33.

  In addition to the inverter 13, each of the operating inverters 14, 15, and 16 can be selected by controlling the switch selection circuit 33 with an external control signal and turning on / off the switching elements SW1, SW2, and SW3. As a result, the amplification degree of the amplification unit can be changed. That is, the inverters 13, 14, 15, 16, the switching elements SW 1, SW 2, SW 3, and the switch selection circuit 33 are means for changing the negative resistance value and are the amplifying units of the IC circuit 12. A means for changing the amplification degree of 14, 15, 16 is configured. Although not shown, the crystal oscillator 20 is entirely sealed in a ceramic package.

  In general, the degree of amplification can be increased by increasing the number of inverters 13, 14, 15, 16 connected in parallel, thereby increasing the mutual conductance and increasing the negative resistance, while the inverter It is known that the degree of amplification can be reduced by reducing the number of 13, 14, 15 and 16 connected in parallel, thereby reducing the mutual conductance and reducing the negative resistance value. Yes. In the present embodiment, among the known matters described in the first embodiment, the relationship between the power supply voltage of the inverter 3, the mutual conductance and the negative resistance value is changed, and the inverters 13, 14, 15, 16 are changed. The quality of the crystal unit 11 is determined by applying the relationship between the increase / decrease in the amplification degree due to the number of parallel connections, the mutual conductance, and the negative resistance value.

  Specifically, the switching elements SW1, SW2, and SW3 are turned on to cause the crystal oscillator 10 to oscillate, and the oscillation output is monitored with an oscilloscope or the like, while the switch selection circuit 33 is controlled by an external control signal. Thus, the switching elements SW1, SW2 and SW3 are sequentially turned off, the amplification degree of the amplifying unit composed of the inverters 13, 14, 15 and 16 is reduced, and the negative resistance value of the IC circuit 12 is gradually reduced. Go. If the negative resistance value at the time of stopping the oscillation is the series resonance resistance value of the crystal unit 11 and the negative resistance value set at the time of designing the IC circuit 12 is 5 times or more of the series resonance resistance value, The crystal resonator 11 is determined to be a non-defective product if it has not reached 5 times.

  When using the crystal oscillator 20 after the pass / fail judgment of the crystal unit 11, the switching elements SW1, SW2, SW3 are turned on / off so that the amplification degree of the inverters 13, 14, 15, 16 becomes a set value at the time of designing the IC circuit 12. The state is controlled by the switch selection circuit 33. Normally, all the switching elements SW1, SW2 and SW3 are used in the on state.

  Next, a third embodiment will be described. As shown in FIG. 3, the crystal oscillator 30 includes a crystal resonator 21 that generates a voltage that vibrates at a specific frequency to be determined, and an IC circuit 22 that oscillates the crystal resonator 21. Has an input terminal IN. The IC circuit 22 is connected in parallel with the crystal resonator 21 and an inverter 23 which is an amplifying unit for amplifying the oscillation voltage, a feedback resistor 24 connected in parallel to the inverter 23, an input terminal of the inverter 23, and an output One end of each electrode is connected to the end, and the other end includes grounded load capacitors 25 and 26 and variable load capacitors 27 and 28. The variable load capacitors 27 and 28 are configured to receive a control signal from the input terminal IN.

  The load capacitance value can be changed by changing the capacitance value of each of the variable load capacitances 27 and 28 by an external control signal. That is, the variable load capacitors 27 and 28 constitute means for changing the capacitance values of the load capacitors 25, 26, 27, and 28 as means for changing the negative resistance value. Although not shown, the crystal oscillator 30 is entirely sealed in a ceramic package.

  In general, it is known that increasing the capacitance values of the load capacitors 25, 26, 27, and 28 decreases the negative resistance value, while decreasing the capacitance value increases the negative resistance value. ing. In the present embodiment, among the known matters described in the first embodiment, the relationship between the power supply voltage of the inverter 3, the mutual conductance, and the negative resistance is changed to the load capacitance value and the negative resistance value. By applying the relationship, the quality of the crystal unit 31 is determined.

  Specifically, the crystal oscillator 30 is oscillated with the capacitance values of the variable load capacitors 27 and 28 minimized, and the oscillation output is monitored by an oscilloscope or the like, while each variable is controlled by an external control signal. The capacitance values of the load capacitors 27 and 28 are sequentially increased, and the negative resistance value of the IC circuit 22 is gradually decreased. If the negative resistance value at the time of stopping the oscillation is the series resonance resistance value of the crystal unit 31, and the negative resistance value set at the time of designing the IC circuit 22 is 5 times or more of the series resonance resistance value, The crystal resonator 31 is determined to be a non-defective product if it does not reach 5 times.

  When using the crystal oscillator 30 after the pass / fail judgment of the crystal resonator 21, the variable load capacitors are set so that the load capacitance values of the load capacitors 25 and 26 and the variable load capacitors 27 and 28 become the set values at the time of circuit design. The capacitance values 27 and 28 are controlled. Normally, the capacitance values of the variable load capacitors 27 and 28 are set to the minimum.

  In each of the above-described embodiments, the negative resistance value is changed and the negative resistance value when the oscillation is stopped is the series resonance resistance value of the crystal resonators 1, 11, and 21. Conversely, by comparing the negative resistance value at the start of oscillation as the series resonance resistance value of the crystal resonators 1, 11, and 21 with the negative resistance value set at the time of designing the IC circuits 2, 12, and 22. The quality of the crystal resonators 1, 11, 21 may be determined. Further, the series resonance resistance values of the crystal resonators 1, 11, 21 are obtained from the negative resistance values in the two states when the oscillation is stopped and when the oscillation is started, and this value is obtained as the IC circuit 2, 12. , 22 may be compared with the negative resistance values set at the time of design, and the quality of the crystal resonators 1, 11, 21 may be determined.

1,11,21 Crystal oscillator 2,12,22 IC circuit 3,13,14,15,16,23 Inverter 4,17,24 Feedback resistor 5,6,18,19,25,26 Load capacity 7 Voltage regulator 8 Voltage controller 27, 28 Variable load capacity 10, 20, 30 Crystal oscillator 33 Switch selection circuit IN Input terminal SW1, SW2, SW3 Switching element

Claims (4)

  The crystal resonator to be determined and the IC circuit that oscillates the device are sealed in the package so that the wiring that connects them is not exposed to the outside, and has a terminal for inputting an external signal. Using a crystal oscillator having means for changing the negative resistance value of the IC circuit according to a signal, the oscillation output is monitored while changing the negative resistance value, and when the oscillation is stopped and / or when the oscillation starts The series resonance resistance value of the crystal resonator is obtained from the resistance value, and the quality of the crystal resonator is determined based on the relationship between the series resonance resistance value and the negative resistance value set when the IC circuit is designed. A quality determination method for a crystal resonator, characterized by:   2. The crystal resonator quality determination method according to claim 1, wherein the means for changing the negative resistance value of the IC circuit is a means for changing a supply voltage to the amplification section of the IC circuit.   2. The crystal resonator quality determination method according to claim 1, wherein the means for changing the negative resistance value of the IC circuit is means for changing the amplification degree of the amplification section of the IC circuit.   2. The crystal resonator quality determination method according to claim 1, wherein the means for changing the negative resistance value of the IC circuit is means for changing the capacitance value of the load capacitance of the IC circuit.

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