JP2001267915A - Phase locked loop oscillator and output circuit for the oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems of a conventional phase locked loop oscillator that has a complicated configuration, requires high power consumption, and has an output change due to a temperature change because of employment of an isolation amplifier to reduce the effect of load fluctuations. SOLUTION: The phase locked loop oscillator can reduce the effect of a load by changing a connection method of a directional coupler connected to the load or can cope with the effect of the load through the selection of a relation between the frequency characteristic and the oscillated frequency or the provision of the temperature characteristic or the like without the need for additional circuit components, resulting that the increase in the power consumption can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a phase-locked oscillator and an output circuit of an oscillator which reduce the influence of load fluctuation and output fluctuation due to temperature fluctuation.

[0002]

2. Description of the Related Art FIG. 8 shows a circuit configuration of a conventional phase locked oscillator. In the figure, 101 is a voltage controlled oscillator, 102 is a directional coupler, 103 is a phase comparator, 1
04 is a low-pass filter, 105 is a reference oscillator, 106
Is a load, 1021 is an input terminal of the directional coupler 102, 1
022 is an output terminal of the directional coupler 102, 1023 is a coupling terminal of the directional coupler 102, 110 is a load, and 115 is an isolation amplifier. The conventional phase locked oscillator is configured as described above, compares the phase of the output signal of the voltage controlled oscillator 101 with the phase of the output signal of the reference signal oscillator 105, controls the frequency of the voltage controlled oscillator 101 with its output, and loads the output signal. 106.
In order to reduce the effect of load fluctuation, the voltage controlled oscillator 101
An isolation amplifier 115 or an attenuator is inserted between the directional coupler 102 and the directional coupler 102 to reduce the amount of coupling between the voltage controlled oscillator 101 and the load 106.

[0003]

Since the conventional phase-locked oscillator is configured as described above, there is a problem that the isolation amplifier 115 is required, the circuit becomes complicated, and the power consumption increases. In addition, there has been a problem of fluctuation of output fluctuation due to temperature fluctuation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a phase-locked oscillator that reduces the effects of load fluctuation and output fluctuation due to temperature fluctuation.

[0005]

SUMMARY OF THE INVENTION A phase locked oscillator according to the present invention comprises a voltage controlled oscillator, a reference signal generator, and a phase comparator for comparing the output signal of the voltage controlled oscillator with the output signal of the reference signal oscillator. A comparator, a low-pass filter for band-limiting an output signal of the phase comparator, a first line and a second line coupled by a distributed constant circuit, and a first terminal of the first line input to the first terminal. Terminal, the second terminal as an output terminal,
A directional coupler terminating a first terminal at a position facing the input terminal of the second line as a coupling terminal, and terminating the second terminal as an isolation terminal; and a load for output of a voltage controlled oscillator. Wherein the output of the voltage-controlled oscillator is connected to an input terminal and the load is connected to a coupling terminal to reduce the influence of the load.

Also, a voltage controlled oscillator, a reference signal generator, a phase comparator for comparing a phase of an output signal of the voltage controlled oscillator with an output signal of the reference signal oscillator, and a band limit of an output signal of the phase comparator , A first line and a second line are coupled by a distributed constant circuit,
A first terminal of the first line is an input terminal, a second terminal is an output terminal 8, a first terminal of the second line facing the input terminal is a coupling terminal, and a second terminal is a second terminal. A phase-locked oscillator including a directional coupler terminated as an isolation terminal and a load for output of a voltage-controlled oscillator, wherein the output of the voltage-controlled oscillator is connected to a coupling terminal, and the load is connected to an output terminal. The effect of the load is reduced.

Further, the center frequency of the directional coupler is set to an integral multiple of the oscillation frequency of the voltage controlled oscillator so as to reduce the influence of the load.

Further, the output circuit of the oscillator according to the present invention changes the amount of coupling of the directional coupler in accordance with the temperature change to perform temperature compensation.

A side-coupling filter is provided between the directional coupler and the load, and the relationship between the characteristics of the side-coupling filter and the frequency of the passing signal is selected. In this case, temperature compensation is performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a voltage controlled oscillator, 2 is a first line and a second line are coupled by a distributed constant circuit, a first terminal of the first line is an input terminal 21, and a second terminal is an output terminal. 22, a directional coupler that terminates a first terminal at a position facing the input terminal 21 of a second line as a coupling terminal 23, and terminates a second terminal as an isolation terminal. Is a phase comparator for comparing the output signal of the reference signal oscillator with the output signal of the reference signal oscillator 5, 4 is a low-pass filter, 5 is a reference oscillator, and 6 is a load.

In the conventional example shown in FIG.
The directional coupler 102 and the isolation amplifier 115 are provided between the load 01 and the load 106 to secure necessary isolation and reduce the influence of the load. On the other hand, in the configuration of the present invention, the connection method of the directional coupler 2 inserted between the voltage controlled oscillator 1 and the load 6 is changed to
The required isolation of about B or more is ensured. As a result, the circuit configuration is not complicated, and the power consumption can be reduced.

In the case where PLL control is performed using a signal obtained by performing a phase comparison in a low frequency band and a multiplied output of the voltage controlled oscillator output is used as a desired wave, as shown in FIG. By setting the center frequency of the pass band to an integral multiple of the oscillation frequency of the voltage controlled oscillator 1, it is possible to reduce the leakage of harmonics and unnecessary waves output from the voltage controlled oscillator 1 to the output. In particular, since a frequency component lower than the desired wave can be reduced, there is an effect that the oscillation operation can be stabilized by feedback to the voltage controlled oscillator 1 by reflection of the fundamental wave generated at a strong level.

Further, as shown in FIG. 3B, the coupling amount of the directional coupler 2 is controlled so as to change with a temperature change.
The output characteristics of the voltage controlled oscillator are compensated.
That is, as shown in FIG. 3A, the first line (from the input terminal 21 to the output terminal 22) of the directional coupler and the second line (from the coupling terminal 23 to the terminator 241) are connected to an isolation terminal. 24) between the first line and the second line.
The temperature compensation is performed by changing the distance between the lines and controlling the coupling amount.

Embodiment 2 FIG. Next, a second embodiment will be described. FIG. 4 is a configuration diagram according to the second embodiment.
In FIG. 4, components denoted by the same reference numerals as those in FIG. 1 indicate components having the same contents or functions. The components are the same as in FIG. 1, but the connections between the directional coupler 2, the voltage controlled oscillator 1 and the load 6 are different. That is, the coupling terminal 23 of the directional coupler 2 is connected to the output of the voltage controlled oscillator 1, the output terminal 22 is connected to the load 6, and the input terminal 21 is connected to the attenuation circuit 7
To the phase comparator 3. With such a connection, the output is reduced as compared with the first embodiment, but the fluctuation of the oscillation characteristic of the voltage controlled oscillator 1 due to the load fluctuation is reduced.

Embodiment 3 Next, a third embodiment will be described. FIG. 5 is a configuration diagram according to the third embodiment.
In FIG. 5, the same reference numerals as those in FIGS. 1 and 4 indicate the same contents or functions. In FIG. 5, the directional coupler 2
As an example, the microstrip 81 shown in FIG. 6A is inserted between the microstrip 81 and the load 6 with a width W, a shift amount L, and an interval S, and a microstrip-side coupling type filter 8 is inserted. A change in the temperature of the output of the voltage controlled oscillator 1 is compensated for using a change in the characteristic. That is, since the temperature characteristic of the microstrip-side coupled filter 8 changes as shown in FIG. 6B, the amount of change in the pass loss due to the temperature depends on the amount of change required to cancel the output fluctuation of the voltage controlled oscillator 1. If a desired frequency is set at a frequency position where, the temperature can be compensated. In addition, as shown in FIG. 6B, since the selection curve of the filter moves almost in parallel on the frequency axis with the temperature, either the positive fluctuation rate or the negative fluctuation rate can be obtained by setting the frequency position. Has the features that can be.

Embodiment 4 Next, a fourth embodiment will be described. FIG. 7 is a configuration diagram according to the fourth embodiment.
In FIG. 7, components denoted by the same reference numerals as in FIGS. 1, 4, and 5 indicate components having the same contents or functions. Reference numeral 8 denotes a side-coupling type filter, and reference numeral 9 denotes an oscillating frequency peripheral temperature compensating circuit for controlling a control voltage of a voltage controlled oscillator to perform necessary temperature compensation. The frequency variation of the voltage controlled oscillator 1 is compensated by the oscillation frequency temperature compensation circuit 9, and the output level variation is compensated by the side-coupling type filter 8 as in the third embodiment. As described above, the above-described directional coupler that changes the line spacing to control the temperature characteristics or that compensates for the temperature characteristics by using the temperature change of the filter characteristics is used when the signal source is the synchronous oscillator described above. However, the present invention is not limited to this, and can be used for the purpose of compensating the output level of a high-frequency oscillator accompanied by temperature fluctuation.

[0017]

As described above, the phase-locked oscillator according to the present invention comprises the first oscillator between the voltage-controlled oscillator and the load.
And a second line are coupled by a distributed constant circuit, and a first terminal of the first line is an input terminal, a second terminal is an output terminal, and a position of the second line facing the input terminal 7. And a directional coupler that terminates the first terminal as a coupling terminal and the second terminal as an isolation terminal. The output of the voltage controlled oscillator is connected to the input terminal of the directional coupler, and the load is connected to the coupling terminal. As a result, there is an effect that the effect of load fluctuation can be reduced.

Further, the phase locked oscillator according to the present invention comprises:
A first line and a second line are coupled by a distributed constant circuit between the voltage controlled oscillator and the load, a first terminal of the first line is an input terminal, a second terminal is an output terminal, A directional coupler that terminates a first terminal at a position facing the input terminal 7 of the second line as a coupling terminal, and terminates a second terminal as an isolation terminal; and outputs the output of the voltage controlled oscillator to the coupling terminal. Since the load is connected to the output terminal, there is an effect that the influence of the load fluctuation can be reduced.

Further, since the center frequency of the directional coupler is set to an integral multiple of the oscillation frequency of the voltage controlled oscillator, an effect of eliminating unnecessary waves can be obtained. In addition, the reflection of the fundamental frequency component of the voltage-controlled oscillator increases, and the frequency component lower than the desired wave can be reduced. There is also an effect that the operation can be stabilized.

Further, since the coupling amount of the directional coupler is changed corresponding to the temperature change, there is an effect that temperature compensation can be performed without requiring an additional circuit. The same effect can be obtained by applying the temperature compensation method of changing the coupling amount of the directional coupler in accordance with the temperature change regardless of the type of the oscillator.

Further, since the frequency characteristic of the directional coupler changes in response to the temperature change, there is an effect that the temperature can be compensated without requiring an additional circuit. The same effect can be obtained by applying the temperature compensation method of changing the frequency characteristic of the directional coupler in response to the temperature change regardless of the type of the oscillator.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a diagram illustrating frequency characteristics of a directional coupler.

FIG. 3 is a diagram illustrating control of a temperature characteristic of a coupling amount of a directional coupler.

FIG. 4 is a configuration diagram of a second embodiment.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is a diagram illustrating the structure of a side-coupling type bandpass filter and control of temperature characteristics.

FIG. 7 is a configuration diagram of a fourth embodiment.

FIG. 8 is a configuration diagram of a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 voltage controlled oscillator 2 directional coupler 21 input terminal, 22 output terminal, 23 coupling terminal, 3 phase comparator, 4 low-pass filter, 5 reference oscillator, 6 load, 7 subtraction circuit, 8 side coupling filter, 9 Oscillation frequency temperature compensation circuit.

Claims (7)

[Claims] 1. A voltage controlled oscillator, a reference signal generator,
A phase comparator for comparing the phase of the output signal of the voltage-controlled oscillator with the output signal of the reference signal oscillator, a low-pass filter for limiting the band of the output signal of the phase comparator, a first line and a second line; Are connected by a distributed constant circuit, a first terminal of the first line is an input terminal, a second terminal is an output terminal, and a first terminal is located at a position facing the input terminal of the second line. A phase-locked oscillator comprising a directional coupler terminating a terminal of the voltage-controlled oscillator as a coupling terminal and a second terminal as an isolation terminal, and a load for output of the voltage-controlled oscillator. A phase-locked oscillator, wherein the load is connected to the input terminal and the load is connected to the coupling terminal. 2. A voltage controlled oscillator, a reference signal generator,
A phase comparator for comparing the phase of the output signal of the voltage-controlled oscillator with the output signal of the reference signal oscillator, a low-pass filter for limiting the band of the output signal of the phase comparator, a first line and a second line; Are connected by a distributed constant circuit, a first terminal of the first line is an input terminal, a second terminal is an output terminal, and a first terminal is located at a position facing the input terminal of the second line. , A phase-locked oscillator comprising a directional coupler terminated with a terminal as a coupling terminal and a second terminal as an isolation terminal, and a load for output of the voltage-controlled oscillator. A phase-locked oscillator wherein the load is connected to the coupling terminal and the load is connected to the output terminal. 3. The phase-locked oscillator according to claim 1, wherein the center frequency of the directional coupler is an integral multiple of the oscillation frequency of the voltage controlled oscillator. 4. The phase-locked oscillator according to claim 1, wherein the coupling amount of the directional coupler changes in response to a temperature change. 5. A side-coupling type filter so that a pass loss caused by a temperature change of a side-coupling filter provided between a directional coupler and a load changes in a direction opposite to a level fluctuation of an input signal of the side-coupling filter. The phase-locked oscillator according to any one of claims 1 to 4, wherein temperature compensation is performed by setting a relationship between a filter characteristic and a frequency of a passing signal. 6. An output circuit of an oscillator for guiding an output signal of an oscillator to a load via a directional coupler, wherein the directional coupler changes a coupling amount between its input terminal and the coupling terminal in response to a temperature change. An output circuit of an oscillator, comprising: a temperature compensating unit for causing the temperature to be compensated. 7. An output circuit of an oscillator for guiding an output signal of an oscillator to a load through a side coupling filter, wherein a passage loss due to a temperature change of the side coupling filter provided between the directional coupler and the load is reduced. The relationship between the characteristics of the side-coupled filter and the frequency of the passing signal is set so as to perform temperature compensation so as to change in the opposite direction to the level fluctuation of the input signal of the side-coupled filter. Characteristic oscillator output circuit.