JPS6028416B2 - Digitally controlled temperature compensated piezoelectric oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digitally controlled temperature compensated piezoelectric oscillator.

2. Description of the Related Art Conventionally, piezoelectric oscillators with high frequency stability have been required to be used as highly stable carrier wave generation sources and timing signal generation sources in carrier devices and the like.

The frequency and temperature characteristics of this piezoelectric oscillator mainly depend on the frequency and temperature characteristics of the piezoelectric oscillator. Temperature-compensated piezoelectric oscillators that correct frequency-temperature characteristics have been put into practical use. As shown in Fig. 1, in a conventional temperature compensated piezoelectric oscillator, a voltage stabilized by a reference voltage generating section 1 using a constant voltage diode, etc. is connected to a temperature variable resistor such as a thermistor, and a fixed resistor. It is converted into a temperature-dependent voltage for correcting the frequency/temperature characteristics of the voltage-controlled piezoelectric oscillator 3 via the circuit network 2, and this voltage is applied to the voltage-controlled piezoelectric oscillator 3 including the voltage-controlled variable capacitance element.

-However, with this type of piezoelectric oscillator, the required temperature compensation voltage differs for each piezoelectric oscillator due to manufacturing errors in voltage controlled capacitance variable elements, temperature variable resistors, etc., and this is different between temperature variable resistors and fixed resistors. In order to adjust the combination, it is necessary to perform approximate calculations using a computer or the like, and the biggest drawback is that it requires a large amount of adjustment man-hours. SUMMARY OF THE INVENTION An object of the present invention is to provide a digitally controlled temperature-compensated piezoelectric oscillator that can easily generate and adjust a temperature-compensated voltage.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 shows a block diagram of one embodiment of the invention. Here, the piezoelectric oscillator of the present invention is composed of a step wave voltage generating section 11, a temperature/voltage converting section 12 consisting of a combination network of a temperature variable resistor such as a thermistor and a fixed resistor, a differential multiplier, etc. a voltage comparison section 13, a waveform shaping circuit section 14 that converts the signal output from the voltage comparison section into a steep pulse voltage, a storage circuit section 15, a digital/analog converter 16, a piezoelectric oscillator, and a voltage controlled capacitance variable element. Includes a voltage controlled piezoelectric oscillator 17, an oscillation circuit 21 that generates a pulse voltage, a counting circuit 22, a digital-to-analog converter 23, and a counting circuit 22.
It consists of a latch circuit 24 and a storage circuit 25 for transmitting the digital amount generated in the storage circuit to the storage circuit.

When the oscillation circuit 21 of FIG. 2 is constituted by an RC oscillation circuit using a differential multiplier shown in FIG. 6, a pulse voltage shown in characteristic (3) of FIG. 3 is generated. This pulse voltage is applied to a counting circuit 22 and a digital/analog converter 2 shown in FIG.
3, a staircase wave voltage shown in characteristic (3) in FIG. 3 is generated. That is, in FIG. 2, the output waveform of the step wave voltage generating section 11 has a characteristic (2) in FIG. 3. This voltage is compared with the DC temperature-dependent voltage generated by the temperature/voltage converter 12 shown in FIG. 2 in the voltage comparator 13, and when the two voltages match, a trigger voltage is generated. Next, the waveform shaping circuit 14 converts the voltage into a pulse voltage having the characteristic (3) in FIG. FIG. 3 shows an example of the temperature/voltage converter 12 and voltage comparator 13 shown in FIG. 2.

The digital quantity of the counting circuit 22 of FIG. 2 at time T is set in the latch circuit 24 by the pulse voltage of the characteristic (1) of FIG. 3.
and is held until a pulse voltage is generated in the next staircase voltage generation cycle. On the other hand, the storage circuit 25 stores in advance a digital amount necessary for temperature compensation corresponding to the input digital amount. This is then passed through the digital-to-analog converter 16 to the voltage-controlled piezoelectric oscillator 1.
Temperature compensation is performed by applying it as an analog voltage to the voltage controlled variable capacitance element 7. FIG. 4 shows an example of changes in output voltage with respect to temperature changes in each part.

Here, the temperature compensation voltage necessary for the voltage-controlled piezoelectric oscillator 17 of FIG. 2 is shown based on the characteristics shown in FIG. 4. Characteristic 31 shows voltage changes occurring in temperature/voltage converter 12 in FIG.
Characteristic 32 shows the voltage changes produced by digital-to-analog converter 16 of FIG. Characteristic 33 shows a state in which the voltage of characteristic 32 is made to have a linear voltage change by an integrating circuit (not shown) on the control voltage input side of the voltage controlled piezoelectric oscillator 17. FIG. 5 shows an example of the characteristics of the piezoelectric oscillator of the present invention.

Here, characteristic 5 shows the characteristic before temperature compensation, and characteristic 51 shows the characteristic after temperature compensation. As described above, in the present invention, the digital quantities required for temperature compensation corresponding to the input digital quantities to the memory circuit 25 at each temperature are stored in advance in the memory circuit 25, so that approximate calculations can be performed using a computer or the like. Without,
A highly stable piezoelectric oscillator that is easy to adjust and reliable can be realized.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional temperature compensated piezoelectric oscillator, Fig. 2 is a block diagram of an embodiment of the present invention, Figs. 3 and 4 are diagrams for explaining the present invention, and Fig. 5 is a block diagram of a conventional temperature compensated piezoelectric oscillator. A diagram showing the characteristics of the piezoelectric oscillator of the present invention and FIGS. 6 to 8 are diagrams showing the configuration of each part of the piezoelectric oscillator of the present invention. In FIG. 2, 11 is a staircase voltage generation section, 12 is a temperature/voltage conversion section, 13 is a voltage comparison section, 14 is a waveform shaping circuit section, 15 is a storage circuit section, 16 is a digital/analog converter, and 17 is a A voltage-controlled piezoelectric oscillator includes a piezoelectric oscillator and a voltage-controlled capacitance variable element, 21 is an oscillation circuit, 22 is a counting circuit, 23 is a digital-to-analog converter, 24 is a latch circuit, and 25 is a storage circuit. 3rd fin Nozomi box 4th picture leopard 5th picture scheme 7th picture chrysanthemum box

Claims (1)

[Claims] 1. A staircase voltage generation section consisting of an oscillator, a counting circuit that converts the oscillation frequency of this oscillator into a digital quantity, and a digital-to-analog converter that converts the digital quantity into an analog quantity, and a DC voltage generator that follows ambient temperature changes. a temperature/voltage converter that generates a voltage, a voltage that changes in a stepwise manner at a constant cycle generated by the step wave voltage generator, and a DC voltage that follows ambient temperature changes that is generated by the temperature/voltage converter. a waveform shaping circuit that converts the voltage from the comparison section into a steep pulse voltage; storage means for outputting a pre-stored digital quantity supplied as an input and corresponding to the output signal; means for converting the digital quantity from the storage means into an analog voltage; and means for converting the analog voltage from the conversion means. 1. A digitally controlled temperature compensated piezoelectric oscillator comprising a supplied voltage controlled piezoelectric oscillator.