JP2007300475A - Reference voltage adjusting method for voltage controlled oscillator, and voltage controlled oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting the reference voltage of a voltage controlled oscillator, capable of raising linearity in relation between a control voltage and a frequency by adjusting the anode voltage of a variable capacity diode, and to provide the voltage controlled oscillator. <P>SOLUTION: The voltage controlled oscillator 10 includes: a piezoelectric vibration piece 12; the variable capacity diode Cv connected to the piezoelectric vibration piece 12 at the cathode side; a reference voltage generation source 16 connected to the anode side of the variable capacity diode Cv; and resistances to be connected to the anode side of the variable capacity diode Cv at one ends and to be connected to pads 18 at the other ends. The voltage controlled oscillator 10 includes a package for mounting the piezoelectric vibration piece 12, the variable capacity diode Cv, the reference voltage generation source 16, and the resistances. The package includes a bonding electrode for grounding, which is conducted/not conducted to the pads 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reference voltage adjustment method for a voltage controlled oscillator and a voltage controlled oscillator.

  In the voltage controlled oscillator, a variable capacitance diode is connected to a piezoelectric vibrating piece, and the oscillation frequency is changed by changing the capacitance of the variable capacitance diode by applying a control voltage from a control terminal. This variable capacitance diode utilizes the fact that when a reverse voltage is applied between the anode and the cathode, the depletion layer capacitance of the pn junction changes due to the change in the reverse voltage.

  FIG. 7 is an explanatory diagram of the prior art. Here, FIG. 7A is a schematic block diagram of a voltage controlled oscillator according to the prior art, and FIG. 7B is a diagram showing the relationship between voltage and capacitance in a variable capacitance diode. The voltage controlled oscillator 1 includes a circuit (oscillation circuit 3) that oscillates the piezoelectric vibrating piece 2 in addition to the piezoelectric vibrating piece 2 and the variable capacitance diode Cv described above. A compensation voltage generator 4 (control circuit) is connected to the control terminal of the voltage controlled oscillator 1. The compensation voltage generator 4 outputs a control voltage Vs to a control terminal, and often uses a single power supply integrated circuit (IC).

  However, in this case, the minimum voltage of the control voltage Vs output from the compensation voltage generator 4 is not 0V but is about 0.6V. Since the minimum voltage applied between the anode and cathode of the variable capacitance diode Cv is about 0.6 V, a portion indicated by an arrow C in FIG. 7B, that is, a region where the capacitance change is large in the relationship between voltage and capacitance. Could not be used.

Therefore, in the invention disclosed in Patent Document 1, in order to use the voltage of the variable capacitance diode from zero volts, a constant voltage is applied to the variable capacitance diode to increase the anode voltage, and the difference voltage between the anode and the cathode is reduced to zero. In addition to obtaining the maximum capacitance value of the variable capacitance diode, it is possible to control a highly linear portion where the differential voltage is near zero.
JP 2000-151281 A

  Since the variable capacitance diode described above has variations for each element, the same capacitance value is not always obtained even when the same voltage is applied between the anode and the cathode. For this reason, in the invention disclosed in Patent Document 1, a constant voltage value is set for each voltage controlled oscillator according to the variation for each variable capacitance diode in order to use the most linear portion of the capacitance change of the variable capacitance diode. Must. However, in the invention disclosed in Patent Document 1, an adjustment circuit is required for this setting, and the circuit in the voltage controlled oscillator becomes complicated.

  Some oscillation circuits have different power supply voltage specifications. For example, the specifications of the power supply voltage include 3.3V, 2.5V, and 1.8V. FIG. 8 is a diagram showing the relationship between the frequency deviation of the voltage controlled oscillator according to the prior art and the control voltage. Here, FIG. 8A and FIG. 8B have the same characteristics, but have different power supply voltage specifications, so the variable range of the control voltage is different. In a voltage controlled oscillator having a wide control voltage variable range (high power supply voltage) as shown in FIG. 8A, a frequency variable range higher than the control voltage center value (center voltage V0), and the center voltage The frequency variable range on the lower voltage side is the same. On the other hand, in the voltage controlled oscillator having a narrow control voltage variable range (low power supply voltage) as shown in FIG. 8B, the frequency variable range D on the higher voltage side than the center voltage V0 and lower than the center voltage V0. The frequency variable range E on the voltage side is different.

  In order to correct the difference in the frequency variable range as shown in FIG. 8B and make the frequency variable range higher and lower than the center voltage equal, it depends on the power supply voltage of the oscillation circuit. The center voltage V0 may be changed. That is, the center voltage V0 may be changed by applying a voltage to the anode side of the variable capacitance diode according to the specification of the power supply voltage. However, in the invention disclosed in Patent Document 1, in order to change the center voltage, a plurality of circuits for applying a constant voltage to the variable capacitance diode must be designed and prepared according to the specifications of the power supply voltage, and the manufacturing cost is increased. Will increase.

  The present invention provides a reference voltage adjustment method for a voltage controlled oscillator and a voltage controlled oscillator that improve the linearity of the relationship between the control voltage and the frequency by adjusting the reference voltage supplied to the variable capacitance diode. Objective.

  According to the reference voltage adjusting method of the voltage controlled oscillator of the present invention, the reference voltage generating source is connected to the anode side of the variable capacitance diode whose cathode side is connected to the piezoelectric vibrating piece, and a plurality of resistors having the other open side are connected in parallel. The frequency of the piezoelectric vibrating piece when the other of the plurality of resistors connected in parallel is selected and grounded is measured, and the resistor that connects the other is determined based on the frequency measurement result.

  That is, in the voltage controlled oscillator reference voltage adjusting method according to the present invention, the other one of the resistors connected to the piezoelectric vibrating piece via the variable capacitance diode is opened, the reference voltage is applied to the variable capacitance diode, and the oscillator output signal The other end of the resistor is short-circuited to the ground, a reference voltage divided by this resistor is applied to the variable capacitance diode, and the frequency of the oscillator output signal is measured. The anode voltage is determined, the other end of the resistor is determined to be connected to the ground or opened, and the other end of the determined resistor is connected to the ground. Further, the reference voltage adjusting method for the voltage controlled oscillator according to the present invention obtains in advance the frequency of the oscillator output signal when the other one of the resistors connected to the piezoelectric vibrating piece is short-circuited to the ground via the variable capacitance diode, and the variable capacitance Open the other of the resistors connected to the piezoelectric resonator element via the diode, apply a reference voltage to the variable capacitance diode, measure the frequency of the oscillator output signal, and calculate the frequency of the oscillator output signal from the previously determined result and measurement result. The other end of the resistor is determined to be connected to the ground or open, and the other end of the determined resistor is connected to the ground.

  Accordingly, it is possible to determine whether to connect or open the pad connected to the resistor and the ground. By connecting or releasing the pad and the ground according to this determination, the reference voltage can be divided and the anode voltage of the variable capacitance diode can be changed. Therefore, the linearity of the relationship between the control voltage and the frequency can be improved.

  The voltage controlled oscillator according to the present invention includes a variable capacitance diode whose cathode side is connected to the piezoelectric vibrating piece, a resistor connected in series to the anode side of the variable capacitance diode, and one connected to the anode side of the variable capacitance diode, the other being And a resistor connected to the pad. In this case, the voltage controlled oscillator can include a plurality of resistors, one connected to the anode side of the variable capacitance diode and the other connected to the pad. Since the voltage dividing ratio can be adjusted by short-circuiting or opening the pad connected to the resistor to the ground, the anode voltage of the variable capacitance diode can be changed, and the linearity of the relationship between the control voltage and the frequency can be improved. In addition, since the voltage dividing ratio can be adjusted with a simple circuit in which a pad is connected to a resistor, the internal circuit of the voltage controlled oscillator does not become complicated. Furthermore, since the anode voltage can be changed in the same circuit regardless of the specification of the power supply voltage of the oscillation circuit, the manufacturing cost can be reduced.

  The voltage controlled oscillator according to the present invention includes a piezoelectric vibrating piece, a variable capacitance diode having one end (cathode side) connected to the piezoelectric vibrating piece, and a reference voltage generation source connected to the other end (anode side) of the variable capacitance diode. For the ground that short-circuits or opens the pad, one side is connected to the other end of the variable capacitance diode, and the other is connected to the pad, and the piezoelectric resonator element, variable capacitance diode, reference voltage source and resistor are mounted. And a package provided with a bonding electrode.

  By short-circuiting or opening the pad connected to the resistor to the ground, the reference voltage output from the reference voltage generation source can be divided and adjusted, and the anode voltage of the variable capacitance diode can be changed. For this reason, the linearity of the relationship between the control voltage and the frequency can be improved. In addition, since the voltage dividing ratio can be adjusted with a simple circuit in which a pad is connected to a resistor, the internal circuit of the voltage controlled oscillator does not become complicated. Furthermore, since the anode voltage can be changed in the same circuit regardless of the specification of the power supply voltage of the oscillation circuit, the manufacturing cost can be reduced.

  The voltage controlled oscillator according to the present invention includes a plurality of resistors, and at least one of the pads connected to each resistor and the bonding electrode for grounding are electrically connected by a wire, or all the pads and the bonding electrode for grounding are connected. It is characterized in that the wire is opened without being connected with a wire. Thereby, the anode voltage of the variable capacitance diode can be set finely.

  The reference voltage generation source described above includes an input terminal, an output terminal, and a control terminal, and is characterized in that one of the resistors described above is connected between the other end of the variable capacitance diode and the control terminal. In this case, the other end of this resistor is connected to the pad. Even when the reference voltage generation source is a saturation voltage regulator, the voltage dividing ratio can be adjusted by short-circuiting or opening the pad connected to the resistor to the ground, so that the anode voltage of the variable capacitance diode can be changed. In addition, since the voltage division ratio can be adjusted with a simple circuit with a pad connected to the resistor, the internal circuit of the voltage controlled oscillator does not become complicated, and the anode voltage can be changed with the same circuit regardless of the power supply voltage specifications of the oscillation circuit. Manufacturing cost can be reduced.

  The voltage controlled oscillator according to the present invention is characterized in that a variable capacitance diode, a reference voltage generation source and a resistor are mounted in an IC chip, and a pad is provided on the main surface of the IC chip. Circuits such as these variable capacitance diodes can be easily mounted on the package, and circuits such as these variable capacitance diodes can be miniaturized. Therefore, the planar size of the voltage controlled oscillator can be reduced and the height can be reduced.

  The voltage controlled oscillator according to the present invention includes a plurality of variable capacitance diodes. Thereby, the variable range of the control voltage can be expanded.

  Hereinafter, a reference voltage adjusting method for a voltage controlled oscillator and a voltage controlled oscillator according to a preferred embodiment of the present invention will be described. FIG. 1 is a block diagram of a voltage controlled oscillator. The voltage controlled oscillator 10 includes a piezoelectric vibrating piece 12, a variable capacitance diode Cv, an oscillation circuit 14, a reference voltage generation source 16, a plurality of resistors R1, R2, R3, R4, R5, a bypass capacitor C, a power supply voltage terminal Vdd, a control terminal. Vc and ground terminal 22 are provided.

  The piezoelectric vibrating piece 12 is an element that oscillates at a constant frequency. For example, the piezoelectric vibrating piece 12 may be a piezoelectric vibrating piece using an AT-cut piezoelectric substrate, a tuning fork type piezoelectric vibrating piece, or a surface acoustic wave resonance piece. The piezoelectric vibrating piece 12 is connected to the cathode side of the variable capacitance diode Cv and to the control terminal Vc. The piezoelectric vibrating piece 12 is connected to the oscillation circuit 14. The oscillation circuit 14 oscillates the piezoelectric vibrating piece 12. The power supply voltage terminal Vdd is connected to the input side of the reference voltage generation source 16. The reference voltage generation source 16 inputs a power supply voltage and outputs a reference voltage Vr.

  The output side of the reference voltage generation source 16 is connected to the anode of the variable capacitance diode Cv. A first resistor R1 is connected in series between the reference voltage generation source 16 and the variable capacitance diode Cv. A second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a bypass capacitor C are connected in parallel between the reference voltage generation source 16 and the variable capacitance diode Cv. That is, the anode of the variable capacitance diode Cv is connected to one of the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the bypass capacitor C. The other of the second resistor R2, the third resistor R3, and the fourth resistor R4 is connected to the pad 18. The first to fourth resistors R1 to R4 are provided to divide the reference voltage Vr output from the reference voltage generation source 16 and adjust the voltage (anode voltage Va) on the anode side of the variable capacitance diode Cv. . The other of the fifth resistor R5 and the bypass capacitor C is connected to the ground (GND).

  The variable capacitance diode Cv, the oscillation circuit 14, the reference voltage generation source 16, the first to fifth resistors R1 to R5, and the bypass capacitor C can be integrated into the IC chip 20. When the IC chip 20 is used, the pads 18 connected to the second to fourth resistors R2 to R4, the control terminal Vc, the power supply voltage terminal Vdd, the ground terminal 22, and terminals that are electrically connected to the piezoelectric vibrating piece 12 (not shown). May be provided on the main surface of the IC chip 20.

  FIG. 2 is a plan view of the voltage controlled oscillator. In FIG. 2, the description of the lid bonded to the upper surface of the package base and the piezoelectric vibrating piece fixed to the package base is omitted. The voltage controlled oscillator 10 includes a package 30. The package 30 includes a package base 32 and the lid. The package base 32 includes a recessed portion 34 that opens upward in order to mount the piezoelectric vibrating piece 12 and the IC chip 20. The recessed portion 34 includes a stepped portion having side surfaces formed in a stepped shape. This step portion has two steps, the first step portion 36 on the lower side and the second step portion 38 on the upper side. A plurality of bonding electrodes 40 are provided on the upper surface of the first staircase portion 36. One of the plurality of bonding electrodes 40 (ground bonding electrode 40 a) is electrically connected to a ground external terminal (not shown) provided on the back surface of the package base 32. In addition to the ground function, the bonding electrode 40 has a function of supplying an electric signal to the piezoelectric vibrating piece 12, a function of inputting a signal output from the piezoelectric vibrating piece 12, and a function of supplying a power supply voltage to the IC chip 20. A function for receiving a signal output from the IC chip 20 and a function for supplying a control voltage to the IC chip 20 are assigned.

  A plurality of mount electrodes 42 are provided on the upper surface of the second stepped portion 38. The mount electrode 42 is a portion to be joined to the piezoelectric vibrating piece 12 when the piezoelectric vibrating piece 12 is mounted on the package base 32. The mount electrode 42 is electrically connected to the bonding electrode 40. That is, the mount electrode 42 has a one-to-one correspondence with the bonding electrode 40 assigned with a function of supplying an electric signal to the piezoelectric vibrating piece 12 and the bonding electrode 40 assigned with a function of inputting a signal output from the piezoelectric vibrating piece 12. Is conducting.

  The IC chip 20 is fixed to the bottom surface of such a package base 32. The main surface of the IC chip 20 faces upward, and the wires 44 are joined to the terminals and bonding electrodes 40 provided on the IC chip 20 so that they are electrically connected. The wire 44 is bonded so that the function of each terminal provided on the IC chip 20 matches the function assigned to the bonding electrode 40. For example, the wire 44 is bonded to the control terminal Vc of the IC chip 20 and the bonding electrode 40b to which the function of supplying the control voltage to the IC chip 20 is assigned, and these are conducted.

  Further, by bonding the wire 44 to at least one of the pads 18 and the ground bonding electrode 40a, the reference voltage Vr is divided to set the anode voltage Va, or the wires 44 are not bonded to all the pads 18. Thus, the reference voltage Vr is divided to set the anode voltage Va. That is, the voltage dividing ratio is adjusted by the first to fourth resistors R1 to R4 by appropriately connecting the other ends of the second to fourth resistors R2 to R4 to the ground or not to the ground, and the anode voltage Va. Has changed.

  An example of the range (setting range) in which the anode voltage Va changes is as follows. FIG. 3 is an explanatory diagram showing an example of the setting range of the anode voltage Va. Here, FIG. 3A is a block diagram showing a part of the voltage controlled oscillator, and FIG. 3B shows the anode voltage Va when each pad is selected and connected to the bonding electrode for ground. . In the case illustrated in FIG. 3, the first resistor R1 is 50 kΩ, the second resistor R2 is 50 kΩ, the third resistor R3 is 20 kΩ, the fourth resistor R4 is 12 kΩ, the fifth resistor R5 is 1 kΩ, and the reference voltage Vr is 1V. It has become. When all the pads 18 connected to the second to fourth resistors R2 to R4 and the bonding electrode 40a for ground are not conductive (all open), the anode voltage Va is 0.02V as shown in FIG. Become. Further, as shown in FIG. 3A, the pad 18 connected to the fourth resistor R4 and the bonding electrode 40a for ground are electrically connected by a wire 44 (short circuit), and the pad is connected to the second resistor R2 and the third resistor R3. 18 and the ground bonding electrode 40a are not conductive (open), the anode voltage Va is 0.2V as shown in FIG. 3B. The anode voltage Va when the pad 18 connected to the second to fourth resistors R2 to R4 and the bonding electrode for ground 40a are made conductive or not conductive is 0.02V as shown in FIG. 3B. It changes in the range up to 0.62V. For this reason, the anode voltage Va may be determined within this set range.

  Note that the resistance values of the resistors R1 to R5 and the setting range of the anode voltage Va are not limited to the case illustrated in FIG. That is, the setting range of the anode voltage Va can be arbitrarily set by changing the resistance values of the resistors R1 to R5. Further, the number of resistors R2 to R4 connected to the pad 18 is not limited to three. That is, even if the number of resistors connected to the pad 18 is changed, the setting range of the anode voltage Va can be arbitrarily set.

  Next, a method for manufacturing the voltage controlled oscillator 10 and a method for determining the anode voltage Va will be described. First, the IC chip 20 is mounted on the bottom surface of the package base 32 (concave portion 34). Then, a wire 44 is bonded to each terminal 22, Vc, Vdd and the bonding electrode 40 to make them conductive. Further, the piezoelectric vibrating reed 12 is mounted on the mount electrode 42 to conduct these. Thereafter, the anode voltage Va is determined.

  Specifically, the power supply voltage is first supplied to the IC chip 20 with the other ends of the second to fourth resistors R2 to R4 being opened, and the frequency of the signal (oscillator output signal) output from the voltage controlled oscillator 10 is set. taking measurement. Then, the short-circuit probe connected to the ground is brought into contact with at least one of the pads 18 connected to the second to fourth resistors R2 to R4. As a result, at least one of the second to fourth resistors R2 to R4 is connected to the ground, so that the reference voltage Vr output from the reference voltage generating source 16 is divided, and the anode voltage Va of the variable capacitance diode Cv changes. . Then, the power supply voltage is supplied to the IC chip 20 and the frequency of the oscillator output signal is measured. Since the frequency change of the oscillator output signal is known from these measurement results, the pad 18 to be connected to the ground bonding electrode 40a is determined. In some cases, it can be determined from the measurement results that the bonding electrode 40a for ground and the pad 18 are not connected. Thereafter, based on the determination result, the wire 44 is bonded to the pad 18 to be connected and the ground bonding electrode 40a to be conductive, or the wire 44 is left open without being bonded. The anode voltage Va can be finely adjusted by such a method of determining the anode voltage Va.

  Then, the lid is joined to the upper surface of the package base 32 to hermetically seal the piezoelectric vibrating reed 12 and the IC chip 20. As a result, the voltage controlled oscillator 10 in which the piezoelectric vibrating piece 12 and the IC chip 20 are mounted on the package 30 is obtained.

  Further, as a method for determining the anode voltage Va, a method different from the above-described determination method can be used. First, the frequency of the oscillator output signal when each pad 18 is electrically connected to the ground bonding electrode 40a is simulated in advance. When the voltage controlled oscillator 10 is manufactured, the IC chip 20 is mounted on the bottom surface of the package base 32 (concave portion 34), the wires 44 are bonded to the terminals 22, Vc, Vdd and the bonding electrode 40, and the mount electrode is mounted. After mounting the piezoelectric vibrating reed 12 on 42, the power supply voltage is supplied to the IC chip 20 with the other ends of the second to fourth resistors R2 to R4 open, and the frequency of the oscillator output signal is measured. From this measurement result and simulation result, the frequency change of the oscillator output signal is predicted to determine the pad 18 to be connected to the ground bonding electrode 40a, or the pad 18 is not connected to the ground bonding electrode 40a. And decide. Thereafter, the wire 44 is bonded to the pad 18 to be connected and the ground bonding electrode 40a based on the determination result to be conductive, or the wire 44 is left open without being bonded. The anode voltage Va can be adjusted by such an adjustment method.

  The voltage controlled oscillator 10 manufactured in this way operates as follows. The power supply voltage input from the power supply voltage terminal Vdd is supplied to the reference voltage generation source 16. The reference voltage Vr output from the reference voltage generation source 16 is divided by the first to fourth resistors R1 to R4 to obtain a predetermined anode voltage Va. If a control voltage equal to Va is input from the control terminal Vc, the voltage between the anode and the cathode of the variable capacitance diode Cv becomes zero volts. As a result, in the relationship between the voltage and the capacity, an area having a large capacity change and high linearity is also used, so that the capacity change can be made almost equal on the high voltage side than the center voltage and on the low voltage side. it can. Therefore, even in the frequency variable characteristic indicating the relationship between the control voltage and the frequency deviation, the frequency deviation changes almost linearly in the vicinity of the center voltage of the control voltage, and the variable balance becomes good.

  When the anode voltage Va of the variable capacitance diode Cv is adjusted, the center voltage also changes. FIG. 4 is a diagram showing the relationship between the frequency deviation and the control voltage. For this reason, even if the voltage-controlled oscillator 10 has different power supply voltage specifications, adjusting the anode voltage Va as shown in FIG. 4 causes the center voltage V0 to move to the high voltage side, regardless of the power supply voltage specifications. The frequency variable range A on the higher voltage side than V0 and the frequency variable range B on the lower voltage side than the center voltage V0 are equal.

  According to the voltage controlled oscillator 10 and the reference voltage adjusting method thereof, the reference voltage can be obtained by conducting or not conducting the pad 18 connected to the second to fourth resistors R2 to R4 and the bonding electrode 40a for ground. The anode voltage Va can be changed by changing the voltage division ratio of Vr. Since the resistors R2 to R4 connected to the pad 18 have a simple circuit configuration, the internal circuit of the voltage controlled oscillator 10 is not complicated.

  The anode voltage Va can be changed by the same circuit configuration, that is, a resistor circuit connected to the pad 18 regardless of the variation of the variable capacitance diode Cv and the specification of the power supply voltage of the oscillation circuit 14. For this reason, it is not necessary to design and prepare a circuit in which a constant voltage value is set for each specification of the power supply voltage of the oscillation circuit 14, thereby reducing the manufacturing cost.

  By changing the anode voltage Va, the linearity of the frequency changing in the variable range of the control voltage can be improved, and a good frequency variable balance can be obtained on the higher voltage side than the center voltage and on the lower voltage side than the center voltage. . Note that the change of the voltage division ratio of the reference voltage Vr can be easily performed by wire bonding, so that a complicated IC remote from the outside is unnecessary.

  In the embodiment described above, one variable capacitance diode Cv is connected to the piezoelectric vibrating piece 12, but the present invention is not limited to this embodiment. FIG. 5 is a block diagram of a voltage controlled oscillator including a plurality of variable capacitance diodes. That is, as shown in FIG. 5, if the cathodes of the two variable capacitance diodes Cv1 and Cv2 are connected to the piezoelectric vibrating piece 12, and the anode is connected to the first to fifth resistors R1 to R5, the variable range of the control voltage. Can be widened. Note that three or more variable capacitance diodes may be connected to the piezoelectric vibrating piece 12. A plurality of variable capacitance diodes may be connected in series as well as in parallel. Further, the fifth resistor R5 connected to the anode of the variable capacitance diode may be a capacitor.

  Further, the reference voltage generation source 16 of the above-described embodiment may be a saturation voltage type regulator. FIG. 6 is an explanatory diagram of a voltage controlled oscillator when the reference voltage generation source is a saturation voltage regulator. The input side of the reference voltage generation source 16 (saturation voltage regulator) is connected to the power supply voltage terminal Vdd, and the output side is connected to the anode of the variable capacitance diode Cv. The control terminal 48 of the reference voltage generation source 16 is connected to one end of a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. Pads 18 are connected to the other ends of the seventh to ninth resistors R7 to R9, respectively. The other end of the sixth resistor R6 is connected to the ground. Further, the other end of the tenth resistor R10 is connected to the output side of the reference voltage generation source 16 and the anode of the variable capacitance diode Cv. Even in such a form, a variable capacitance diode Cv is formed by bonding a wire to at least one of the plurality of pads 18 and connecting it to the ground, or opening all the pads 18 without bonding wires. The anode voltage Va can be changed.

It is a block diagram of a voltage controlled oscillator. It is a top view of a voltage controlled oscillator. It is explanatory drawing which shows an example of the setting range of the anode voltage Va. It is a figure which shows the relationship between a frequency deviation and a control voltage. It is a block diagram of a voltage controlled oscillator provided with a plurality of variable capacitance diodes. It is explanatory drawing of the voltage controlled oscillator at the time of using a reference voltage generation source as a saturation voltage type regulator. It is explanatory drawing of a prior art. It is a figure which shows the relationship between the frequency deviation of the voltage control oscillator which concerns on a prior art, and a control voltage.

Explanation of symbols

10 ......... Voltage controlled oscillator, 12 ......... Piezoelectric vibrator, 14 ......... Oscillator, 16 ......... Reference voltage source, 18 ......... Pad, 20 ......... IC chip, 30 ......... Package 44 ......... Wire, Cv ......... Variable capacitance diode.

Claims (7)

A reference voltage generating source is connected to the anode side of the variable capacitance diode whose cathode side is connected to the piezoelectric vibrating piece, and a plurality of resistors having the other opened are connected in parallel.
Measure the frequency of the piezoelectric vibrating piece when the other of the plurality of resistors connected in parallel is selected and grounded,
A reference voltage adjusting method for a voltage controlled oscillator, wherein the resistor for connecting the other is determined based on the frequency measurement result. A variable capacitance diode whose cathode side is connected to a piezoelectric vibrating piece;
A resistor connected in series to the anode side of the variable capacitance diode;
A resistor having one connected to the anode side of the variable capacitance diode and the other connected to the pad;
A voltage-controlled oscillator comprising: A piezoelectric vibrating piece;
A variable capacitance diode having one end connected to the piezoelectric vibrating piece;
A reference voltage source connected to the other end of the variable capacitance diode;
A resistor connected to the other end of the variable capacitance diode and the other connected to the pad;
A package including the piezoelectric vibrating piece, the variable capacitance diode, the reference voltage generation source, and the resistor, and a bonding electrode for a ground that is short-circuited or opened with the pad;
A voltage-controlled oscillator comprising:   A plurality of the resistors are provided, and at least one of the pads connected to each of the resistors and the bonding electrode for ground are electrically connected by a wire, or all the pads and the bonding electrode for ground are electrically connected by a wire. 4. The voltage controlled oscillator according to claim 3, wherein the voltage controlled oscillator is opened. The reference voltage generation source includes an input terminal, an output terminal, and a control terminal,
5. The voltage controlled oscillator according to claim 3, wherein the resistor is connected between the other end of the variable capacitance diode and the control terminal.   6. The voltage according to claim 3, wherein the variable capacitance diode, the reference voltage generation source, and the resistor are mounted in an IC chip, and the pad is provided on a main surface of the IC chip. Controlled oscillator.   The voltage controlled oscillator according to claim 2, comprising a plurality of the variable capacitance diodes.

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