JPH022721A - Phase locked loop oscillation circuit - Google Patents

Abstract

PURPOSE:To stabilize the operation of a voltage controlled oscillator and to prevent step out from being generated by providing an ambient temperature detecting means at a phased locked loop oscillation circuit provided with the voltage controlled oscillator, and impressing a voltage corresponding to a detected temperature on the voltage controlled oscillator as a control voltage. CONSTITUTION:When an ambient temperature is raised, an analog signal is generated in an ambient temperature detector 7, and it is converted to a digital signal by an A/D converter 8, and is inputted to a memory circuit 9. The digital signal corresponding to the one is outputted from the circuit 9, and it is recovered to the analog signal by a D/A converter 10, and is inputted to the voltage controlled oscillator 4, and a variable capacitance device 5 is controlled by the output of the oscillator, then, oscillation output not being affected by the change of the ambient temperature can be obtained. Also, when the ambient temperature drops, a reverse voltage is impressed on the device 5, and the oscillation output not being affected by the ambient temperature can be obtained similarly. Therefore, no change is generated in a frequency and the step-out can be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase synchronized oscillation circuit, and more particularly to a phase synchronized oscillation circuit used as a synchronization circuit for communication devices and the like.

Gen Ryodo 1 Conventionally, this type of phase-locked oscillator circuit has an output frequency of several hundred [
HIIZ]@ area. The conventional phase synchronized oscillation circuit will be explained using the twenty-first. FIG. 2 is a system diagram showing the configuration of a conventional phase-locked oscillator circuit. In FIG. and,
The frequency divider 6 is configured to include a frequency divider 6.

In the conventional phase-locked oscillator circuit having such a configuration, the oscillation output of the piezoelectric oscillator 1 and the output of the frequency divider 6 divided to the same frequency are phase-compared in the phase comparator 2, and this phase difference signal is looped. After smoothing through the filter 3, the output is inputted to the voltage controlled piezoelectric oscillator 4, so that the phases of the outputs of the voltage controlled piezoelectric oscillator 4 and the piezoelectric oscillator 1 are matched (that is, synchronized).

゛In this case, the voltage controlled piezoelectric oscillator 4 has a variable capacitance element 5 (
For example, the variable capacitance element 5 has a configuration in which a control voltage is applied to one end of the variable capacitance element 5, and an internal bias is applied to the other end.

However, in this case, the synchronization range shifts due to the frequency-temperature characteristics of the voltage-controlled piezoelectric oscillator 4, and there is a drawback that synchronization tends to shift at high or low temperatures.For example, as shown in FIG. As the ambient temperature T increases, the oscillation frequency changes Δf/
There was a drawback that f increased in the negative direction and the synchronization range shifted as shown in FIG.

SUMMARY OF THE INVENTION An object of the present invention is to provide a phase-locked oscillator circuit that is less likely to lose synchronization even if the ambient temperature fluctuates.

The phase-locked oscillation circuit of the present invention is a phase-locked oscillation circuit having a voltage controlled oscillator, and includes a temperature detection means for detecting an ambient temperature, and a temperature detection means for detecting the temperature detected by the temperature detection means. It is characterized by comprising a voltage applying means for applying a voltage as a control voltage to the voltage controlled oscillator.

Sister Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a system diagram showing the configuration of an embodiment of a phase-locked oscillation circuit according to the present invention, and parts equivalent to those in FIG. 2 are indicated by the same symbols. In the figure, a phase synchronized oscillation circuit according to an embodiment of the present invention includes a piezoelectric oscillator 1 and a phase comparator 2.
, a loop filter 3 , a voltage-controlled piezoelectric oscillator 4 , and a frequency divider 6 .

The phase synchronized oscillation circuit according to this embodiment also includes an ambient temperature detector 7 and an A/D (analog/digital) converter 8.
, a memory circuit 9 , and a D/A (digital/analog) converter 10 .

The ambient temperature detector 7 has a well-known temperature sensor (for example, a sursistor), and converts changes in ambient temperature into a predetermined analog signal and sends it to the A/D converter 8.

The A/D converter 8 converts the input analog signal into a digital signal and sends it to the memory circuit 9.

The memory circuit 9 has a digital signal corresponding to the voltage necessary for temperature compensation stored in advance at an address designated by the digital signal from the A/D converter 8. Therefore, when the ambient temperature changes, the memory circuit 9 will send out a digital signal necessary for temperature compensation accordingly.

The D/A converter 10 converts the digital signal from the memory circuit 9 into an analog signal and sends it to the voltage-controlled piezoelectric oscillator 4.

The voltage controlled piezoelectric oscillator 4 has a variable capacitance element 5, the output of the phase comparator 2 is input to one end of the variable capacitance element 5 via a loop filter 3, and the D/A converter 1 is input to the other end of the variable capacitance element 5.
An analog signal that is an output of 0 is input.

The piezoelectric oscillator 1; the phase comparator 2, the loop filter 3, and the frequency divider 6 have functions equivalent to those of a conventional phase-locked oscillator circuit (see FIG. 2).

In such a configuration, when the ambient temperature increases, the ambient temperature detector 7 detects it and sends out an analog signal. Then, the analog signal is converted into a digital signal by the A/D converter 8 and then input to the memory circuit 9.

A digital signal corresponding to the digital signal is sent from the memory circuit 9, converted into an analog signal by the D/A converter 10, and then input to the voltage-controlled piezoelectric oscillator 4. By controlling the variable capacitance element 5 using this analog signal, an oscillation output that is not affected by changes in ambient temperature can be obtained.

Further, when the ambient temperature becomes low, a voltage opposite to that in the above case is applied to the variable capacitance element 5, and an oscillation output that is not affected by changes in the ambient temperature can be obtained.

In other words, in the present invention, when the ambient temperature changes, a voltage is applied to the variable capacitance element to cancel out the effect of the change.
A stable oscillation output can be obtained. Therefore, as shown in Figure 3, even if the ambient temperature T fluctuates, the frequency change △f/f will be almost negligible, and as shown in Figure 5, the synchronization range will hardly shift. be.

As explained above, the present invention provides a stable voltage-controlled piezoelectric oscillator that is unaffected by fluctuations in ambient temperature, thereby making it possible to always obtain a constant synchronization range and making it difficult to lose synchronization. It has the effect of being able to

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the configuration of a phase-locked oscillation circuit according to an embodiment of the present invention, FIG. 2 is a system diagram showing the configuration of a conventional phase-locked oscillation circuit, and FIG. 3 is a system diagram showing the configuration of a phase-locked oscillation circuit according to an embodiment of the present invention. An example of the frequency-temperature characteristics of an oscillation circuit, Fig. 4 is an example of the frequency-temperature characteristics of a conventional phase-locked oscillation circuit, Fig. 5 is an example of the synchronization range vs. temperature characteristic of a conventional phase-locked oscillation circuit, and Fig. 6 is an example of the frequency-temperature characteristics of a conventional phase-locked oscillation circuit. 1 is an example of a synchronous purebred-temperature characteristic of a phase-locked oscillation circuit according to an embodiment of the present invention. Explanation of symbols of main parts 4... Voltage controlled piezoelectric oscillator 5... Variable capacitance element

Claims (1)

[Claims] (1) A phase-locked oscillator circuit having a voltage-controlled oscillator, which includes temperature detection means for detecting ambient temperature, and a voltage corresponding to the temperature detected by the temperature detection means, which is applied as a control voltage to the voltage-controlled oscillator. 1. A phase-locked oscillator circuit comprising: voltage applying means.