JPH054329Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a voltage-controlled piezoelectric oscillator, and in particular, the oscillation frequency change characteristic of the piezoelectric oscillator with respect to the applied voltage is switched to a plurality of arbitrarily set frequency characteristic patterns. The present invention relates to a voltage-controlled piezoelectric oscillator that can be used as a voltage-controlled piezoelectric oscillator.

(Prior Art) Conventionally, this type of voltage-controlled piezoelectric oscillator, as shown in FIG. In addition to one side, the oscillation frequency is controlled by changing the capacitance of the variable capacitance element 7 according to the external control voltage value. If it is desired to change the control voltage oscillation frequency characteristics of the piezoelectric oscillator controlled in this manner, the variable capacitance element 7 or other circuit elements constituting the oscillation circuit must be changed.

(Problems to be Solved by the Invention) In general, voltage-controlled piezoelectric oscillators are often required to have a linear change in frequency with respect to the control voltage.

However, in the conventional voltage-controlled piezoelectric oscillator described above, the applied voltage vs. capacitance characteristic of the variable capacitance element used therein has a non-linear portion as shown in FIG. There is a drawback that the oscillation frequency change characteristic with respect to the voltage value has a non-linear portion as shown in FIG.

Also, if you want to change the external control voltage vs. oscillation frequency change characteristic to the desired shape, you will need to change the variable capacitance element that makes up the oscillation circuit or change other elements, but in any case, it is easy to change. The disadvantage is that it is not.

The purpose of the present invention is to eliminate such drawbacks and provide a voltage-controlled piezoelectric oscillator that can have a linear or other desired external control voltage vs. frequency change characteristic, and can be used by switching between multiple characteristics. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, the voltage-controlled piezoelectric oscillator of the present invention includes an analog-to-digital converter (hereinafter referred to as an AD converter) 1 that converts an external control voltage into a digital signal. , a plurality of fixed storage devices (hereinafter referred to as ROM) 3 and 4, which store different digital signals for each storage device for voltage compensation, corresponding to the address specified by the digital signal output from the AD converter 1; A switch section 2 switches the input terminals of the ROMs 3 and 4 and connects them to the output terminal of the AD converter 1, and a digital-to-analog converter (hereinafter referred to as DA conversion) converts the digital signals output from the plurality of ROMs 3 and 4 into analog signals. The piezoelectric oscillator 5 has a piezoelectric oscillator 6 controlled by a voltage, and the output of the DA converter 5 is applied to a variable capacitance element 7 of the piezoelectric oscillator 6.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

As shown in FIG. 1, the output of an AD converter 1 that receives an external control voltage is input to a changeover switch section 2, and the output of the changeover switch section 2 is switched.
In some cases it is given to ROM3 and in some cases it is given to ROM3.
Given to ROM4. The outputs of ROM3 and ROM4 are both input to a DA converter 5, and the output of the DA converter 5 is input to a piezoelectric oscillator 6 controlled by voltage.
is connected to the cathode side of the variable capacitance element 7 via a resistor 8.

The ROM 3 stores, for example, a second
A digital signal as shown in the figure is stored in advance with the input digital signal as a designated address. Further, the ROM 4 stores in advance a digital signal such that the frequency change of the piezoelectric oscillator 6 becomes as shown in FIG. 3 in response to a change in the external control voltage, using the input digital signal as a specified address. There is.

Next, the operation will be explained.

When a control voltage is applied from the outside to the input terminal of the AD converter 1, the AD converter 1 converts it into a digital signal. This digital signal is applied to the ROM 3 or ROM 4 selected by the changeover switch section 2 depending on the desired oscillation frequency change characteristic.
In ROM3 and ROM4, a digital signal corresponding to the voltage required for voltage compensation is stored at the address specified by the digital signal of the AD converter output.
The address signal changes and ROM3 or ROM4
A digital signal corresponding to the voltage required for voltage compensation is read out from.

The digital signal read from the ROM3 or ROM4 is converted into an analog signal by the DA converter 5, and is applied to the variable capacitance element 7 via the resistor 8 to control the capacitance value of the variable capacitance element 7. This controls the oscillation frequency of the piezoelectric oscillator.

In this way, for example, when ROM3 is selected, the external control voltage vs. oscillation frequency change characteristic can be obtained as shown in FIG. 2, and when ROM4 is selected, as shown in FIG. 7.

Then, by changing the set values of the conversion rate of the analog-to-digital converter 1 and the conversion rate of the digital-to-analog converter 5, the slope of the oscillation frequency change characteristic with respect to the external control voltage value can be changed. Can be set.

In addition, by increasing the ROM, the ROM
The desired characteristic can be selected from as many different external control voltage vs. oscillation frequency change characteristics as shown in Figure 2 or 2 by appropriately selecting the signals stored in advance in the ROM. Any characteristic other than the linear characteristic shown in FIG. 3 can also be obtained.

(Effects of the invention) As explained above, the present invention has multiple ROMs, and uses a signal obtained by digitizing an external control voltage as an address to output a control voltage corresponding to the desired voltage compensation from any ROM. By reading out the corresponding digital signal and converting it into analog to control the piezoelectric oscillator, the oscillation frequency characteristics for the external control voltage value can be arbitrarily set.Moreover, by switching multiple ROMs, multiple external control This has the advantage that a voltage-controlled piezoelectric oscillator with voltage versus oscillation frequency change characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 2 and 3 are characteristic curve diagrams showing examples of external control voltage versus frequency change characteristics of the embodiment of FIG. 1. FIG. 4 is a circuit diagram showing an example of a conventional voltage-controlled piezoelectric oscillator. FIG. 5 is a characteristic curve diagram showing an example of the characteristics of the variable capacitance element used in the conventional circuit shown in FIG. FIG. 6 is a characteristic curve diagram showing an example of external control voltage versus frequency change characteristics of the conventional circuit shown in FIG. 1... Analog-digital converter, 2... Selector switch unit, 3, 4... Fixed storage device (ROM),
5... Digital-analog converter, 7... Variable capacitance element, 8... Resistor.

Claims (1)

[Scope of utility model registration request] an analog-to-digital converter that converts an external control voltage into a digital signal; and a storage device that stores a different digital signal for voltage compensation in correspondence with an address specified by the digital signal output from the analog-to-digital converter. a plurality of fixed storage devices; a switch section that switches the input terminals of the plurality of fixed storage devices and connects them to the output terminal of the analog-digital converter; and converts the digital signals output from the plurality of fixed storage devices into analog signals. a voltage-controlled piezoelectric oscillator; and a voltage-controlled piezoelectric oscillator, the voltage is characterized by a configuration in which the output of the digital-analog converter is applied to a variable capacitance element of the piezoelectric oscillator. Controlled piezoelectric oscillator.