JP2001156633A - Frequency synthesizer type oscillation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the effect on an oscillated frequency due to mechanical vibration without the use of a vibration absorbing material and without the need for a variable gain amplifier and a rectifier different from a conventional frequency synthesizer type oscillating circuit. SOLUTION: A vibration sensor 6 detects mechanical vibration applied to a voltage controlled oscillator 1 to provide an output of a vibration detection signal Sv1 denoting magnitude of vibration. An amplifier 7 amplifies the vibration detection signal to a prescribed level, the amplified signal is given to a high pass filter 8, which extracts a component Sv2 not absorbed by a PLL itself among components included in the vibration detection signal and given it to a phase amplitude adjustment device 9. The component Sv2 is adjusted to have a phase inverted to that of the component due to mechanical vibration included in a control signal Sc outputted from a loop filter 5 and to have the same level as that of the component and the adjusted component is fed to a voltage adder 10. The voltage adder 10 adds an output signal Sv3 of the phase amplitude adjustment device 9 to the control signal Sc so as to cancel the component caused by the mechanical vibration that is included in the control signal Sc and cannot be absorbed by the PLL itself.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a PLL (Phase)
More particularly, the present invention relates to a frequency synthesizer type oscillation circuit having a function of reducing fluctuation of an oscillation frequency due to mechanical vibration.

[0002]

2. Description of the Related Art As a high-frequency signal source of a local oscillator of a communication apparatus, a PLL type frequency synthesizer type oscillation circuit having good frequency stability and variable frequency over a wide range is used.

Generally, a frequency synthesizer type oscillation circuit is
The oscillation output of the voltage controlled oscillator is divided by an externally designated dividing ratio, and the divided signal and the reference signal of the reference signal oscillator are input to a phase comparator to detect a phase difference, and a loop filter ( An LPF is supplied as a control signal to a voltage controlled oscillator (VCO) to control the oscillation frequency.

When mechanical vibration is externally applied to the voltage controlled oscillator, the oscillation frequency changes because the inductance and the stray capacitance of the resonance circuit of the voltage controlled oscillator change due to the mechanical vibration. in this case,
The PLL operates to change the control signal in accordance with the change in the oscillation frequency to suppress the change in the oscillation frequency, but cannot sufficiently follow the sudden mechanical vibration.

In order to reduce the fluctuation of the oscillation frequency due to such vibrations, protection is provided by using a vibration absorbing material, and the resonance circuit is firmly fixed. However, when a vibration absorbing material is used, the mounting space becomes large, and even if the resonance circuit is fixed, it may not be possible to reduce the vibration depending on the vibration level.

Means for solving this problem is disclosed in Japanese Patent Laid-Open No. 10-2
No. 24211. FIG. 5 is a block diagram shown in the publication.

In FIG. 1, a portion surrounded by a dotted line is a portion constituting a normal PLL. That is, a voltage-controlled oscillator 1 whose oscillation frequency is controlled by a control signal, a frequency divider 2 that divides the oscillation output of the voltage-controlled oscillator 1 by a specified frequency division ratio, and is divided by the frequency divider 2 Phase comparator 4 for detecting the phase difference between the detected signal and the reference signal of reference signal oscillator 3
And a loop filter (LPF) 5 for generating a control signal by removing unnecessary high frequency components from the output of the phase comparator 4 and supplying the control signal to the voltage controlled oscillator 1.

In such a PLL type frequency synthesizer type oscillation circuit, in order to reduce the fluctuation of the oscillation frequency caused by the mechanical vibration, the oscillation for detecting the mechanical vibration applied to the resonance circuit of the voltage controlled oscillator 1 is described. A sensor 6 is provided, and a voltage adder 10 is provided on the output side of the loop filter 5. Further, an AC component generated in the control signal output from the loop filter 5 due to the vibration is extracted through the coupling capacitor 11, amplified by the amplifier 12, and then rectified by the rectifier 13. The vibration detection signal from the vibration sensor 6 is amplified by the variable gain amplifier 14 whose gain is controlled by the output, and the vibration detection signal amplified by the variable gain amplifier 14 is input to the voltage adder 10 and the loop filter 5
By adding to the control signal output from the controller and canceling the component caused by the mechanical vibration, the fluctuation of the oscillation frequency due to the mechanical vibration is reduced.

[0009]

As described above, in the conventional example, an AC component generated in a control signal output from a loop filter (LPF) due to oscillation frequency fluctuation due to mechanical vibration is extracted and rectified by a rectifier. A variable gain amplifier whose gain is controlled by the rectified output amplifies the detection signal of the vibration sensor, and the vibration detection signal amplified by the variable gain amplifier is input to a voltage adder and added to the control signal, thereby providing a mechanical signal. The component caused by vibration is canceled.

However, since the characteristics of the variable gain amplifier and the rectifier tend to change with changes in temperature, a circuit for compensating for the temperature characteristics is required, and the circuit configuration is complicated to operate in a wide temperature range. There is a problem that the cost increases.

An object of the present invention is to provide a frequency synthesizer type oscillation circuit using a PLL which can reduce the influence of mechanical vibration on the oscillation frequency without using a variable gain amplifier or a rectifier as in the prior art. It is to provide a circuit.

[0012]

A frequency synthesizer according to the present invention divides an oscillation output of a voltage controlled oscillator by an externally designated frequency division ratio, and divides the frequency of the divided output with a reference signal of a reference signal oscillator. In a PLL type frequency synthesizer type oscillation circuit which inputs a comparator to detect a phase difference and supplies it to a voltage controlled oscillator as a control signal via a loop filter to control an oscillation frequency, a vibration received by the voltage controlled oscillator is Detected components are extracted from the components included in the detected vibration, which cannot be absorbed by the PLL itself, and the extracted components cancel out components caused by mechanical vibration included in the control signal.

More specifically, a vibration sensor that detects a vibration received by the voltage controlled oscillator and outputs a vibration detection signal indicative of the vibration, and a P sensor from among the components included in the vibration detection signal
A filter for extracting a component that cannot be absorbed by the LL itself, and a phase and amplitude adjuster that adjusts the component extracted by the filter so that the component included in the control signal has a phase opposite to and the same as that of the component that cannot be absorbed by the PLL itself. A voltage adder that is provided on the output side of the loop filter and that adds the output of the phase amplitude adjuster to the control signal and outputs the control signal to the voltage controlled oscillator.

Further, a vibration sensor for detecting a vibration received by the voltage controlled oscillator and outputting a vibration detection signal indicating the vibration, and a filter for extracting a component that cannot be absorbed by the PLL itself from components included in the vibration detection signal And a phase and amplitude adjuster that adjusts the component extracted by the filter so that the component included in the control signal and which cannot be absorbed by the PLL itself has the opposite phase and the same level. A plurality of variable capacitance elements connected in parallel to a circuit, the control signal being supplied to one of the plurality of variable capacitance elements, and the phase being supplied to another one of the plurality of variable capacitance elements. Provides the output signal of the amplitude adjuster.

In the above configuration, the filter is a PL.
A high-pass filter having characteristics opposite to the frequency characteristics of L itself may be used, or a band-pass filter that extracts a specific frequency from components that cannot be absorbed by the PLL itself may be used. Further, the vibration sensor is arranged near a resonance circuit of the voltage controlled oscillator, and has the same shape and mass as the resonance circuit.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and the same components as those in the conventional example shown in FIG.

In FIG. 1, a portion surrounded by a dotted line is a portion constituting a normal PLL, and a voltage controlled oscillator (VCO) 1 whose oscillation frequency is controlled by a control signal, and an oscillation output of the voltage controlled oscillator 1 A frequency divider 2 for dividing the frequency by an externally designated frequency dividing ratio, a phase comparator 4 for detecting a phase difference between a signal divided by the frequency divider 2 and a reference signal of a reference signal oscillator 3, An unnecessary high-frequency component is removed from the output of the phase comparator 4 to generate a control signal Sc, and the voltage-controlled oscillator 1
And a loop filter (LPF) 5 to be supplied to the power supply.

By the way, in order to reduce the fluctuation of the oscillation frequency caused by the mechanical vibration, a vibration sensor which detects the mechanical vibration applied to the resonance circuit of the voltage controlled oscillator 1 and outputs a vibration detection signal Sv1 indicating the vibration. 6, an amplifier 7 that amplifies the vibration detection signal Sv1 to a predetermined level, and a signal component Sv2 that has a frequency characteristic opposite to that of the PLL itself and cannot be absorbed by the PLL from among the components included in the vibration detection signal. The signal component Sv2 is adjusted so that the high-pass filter (HPF) 8 and the component caused by mechanical vibration included in the control signal Sc output from the loop filter 5 have the opposite phase and the same level. A phase amplitude adjuster 9 that outputs the control signal Sc output from the loop filter 5; It is provided an adder 10.

Here, the vibration sensor 6 is arranged near the resonance circuit and has the same shape as the resonance circuit in order to faithfully detect the vibration received by the resonance circuit of the voltage controlled oscillator 1.
It has the same mass.

The high-pass filter (HPF) 8 is a PLL
It is set so that components that cannot be absorbed by itself are extracted from the vibration detection signal Sv1. FIG. 2 is a diagram illustrating an example of the frequency characteristics of the high-pass filter (HPF) 8 and the frequency characteristics of the PLL itself. The solid line indicates the frequency characteristics of the high-pass filter (HPF) 8. The frequency characteristics of the PLL itself are indicated by broken lines. Thus, the frequency characteristics of the high-pass filter 8 are opposite to the frequency characteristics of the PLL itself.

In general, the frequency characteristic of the PLL is such that the loop gain is reduced from 100 Hz to 1000 Hz or more, as shown by the broken line. For this reason, when mechanical vibration is applied to the voltage controlled oscillator 1 from the outside, the PLL itself follows and reduces the fluctuation component having a high loop gain among the fluctuation components of the oscillation frequency due to the mechanical vibration. ,
The PLL itself cannot follow the fluctuation component in which the loop gain decreases.

The present invention is configured to remove a fluctuation component which cannot be followed by the PLL itself among fluctuation components of the oscillation frequency due to mechanical vibration. That is, the vibration sensor 6 detects the vibration received by the resonance circuit of the voltage controlled oscillator 1, and the high-pass filter (HPF) 8 causes the mechanical vibration that cannot be absorbed by the PLL from the components included in the vibration detection signal Sv 1. By extracting the signal component Sv2, adjusting the phase and amplitude, and adding it to the control signal Sc, the component caused by the mechanical vibration included in the control signal Sc is canceled, and the fluctuation of the oscillation frequency caused by the mechanical vibration is reduced. I try to make it.

In the circuit configuration, a high-pass filter (H
If the signal component Sv2 extracted by the PF) 8 has the opposite phase and the same level as the component caused by the mechanical vibration included in the control signal Sc output from the loop filter 5, the phase amplitude adjuster 9 can be omitted.

Next, the operation will be described.

When the frequency of the resonance circuit of the voltage controlled oscillator 1 fluctuates due to mechanical vibration, the PLL
L operates to suppress frequency fluctuations according to the response of the frequency characteristic of L itself. In this case, of the frequency components of the mechanical vibration, components in a low frequency region where the loop gain is high can be absorbed.

On the other hand, the vibration sensor 6
And outputs a vibration detection signal Sv1 indicating the vibration. The vibration detection signal Sv1 is amplified to a predetermined level and input to a high-pass filter (HPF) 8, and a signal component Sv2 caused by mechanical vibration that cannot be absorbed by the PLL itself is extracted from components included in the vibration detection signal. Is done.

The signal component Sv2 extracted by the high-pass filter (HPF) 8 is input to a phase and amplitude adjuster 9,
After being adjusted to the opposite phase and the same level as the component caused by the mechanical vibration included in the control signal Sc output from the loop filter 5, it is supplied to the voltage adder 10,
Is added to the control signal Sc output from
Components resulting from mechanical vibrations that cannot be absorbed by the PLL itself are canceled out and removed.

FIG. 3 is a block diagram showing another embodiment of the present invention. The same components as those shown in FIG. 1 are denoted by the same reference numerals.

Here, the difference from the embodiment shown in FIG. 1 is that the voltage adder 10 is omitted. That is, the point is that the control signal Sc output from the loop filter 5 and the output signal Sv3 of the phase amplitude adjuster 9 are directly input to the voltage controlled oscillator 11, respectively.

As shown in FIG. 4, the voltage controlled oscillator 11 has two variable capacitance elements D1 and D2 connected in parallel to a resonance circuit. The control signal Sc output from the loop filter 5 is supplied to one variable capacitance element D1, and the output signal Sv3 of the phase amplitude adjuster 9, that is, the control signal Sc is supplied to the other variable capacitance element D2. A signal adjusted in phase and at the same level as the component caused by the included mechanical vibration is supplied. With this configuration, the two variable capacitance elements D <b> 1 and D <b> 1 forming the resonance circuit of the voltage controlled oscillator 11 can be used without using the voltage adder 10.
Since the component caused by mechanical vibration can be canceled by the method 2, the circuit configuration can be further simplified.

In the embodiment shown in FIGS. 1 and 3, as a filter for extracting a component that cannot be absorbed by the PLL itself from the components included in the vibration detection signal, the filter has a high characteristic opposite to the frequency characteristic of the PLL itself. Band pass filter (HP
F) is used, but when the frequency of the mechanical vibration externally applied to the voltage controlled oscillator is limited, or when it is desired to specify and cancel the frequency of the mechanical vibration having a large effect, the high level is used. Instead of a band pass filter (HPF), a band pass filter (BP
F) may be used.

[0033]

As described above, according to the present invention, the vibration sensor detects the vibration received by the resonance circuit of the voltage controlled oscillator, and the PLL is selected from the components included in the vibration detection signal.
By extracting components due to mechanical vibrations that cannot be absorbed by itself and canceling out components due to mechanical vibrations contained in the control signal output from the loop filter, no vibration absorbing material is used. As described above, the influence of the mechanical vibration on the oscillation frequency can be reduced without using a variable gain amplifier or a rectifier.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of frequency characteristics of a high-pass filter (HPF) 8 and a PLL itself illustrated in FIG. 1;

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing an example of a voltage controlled oscillator 11 shown in FIG.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1,11 Voltage controlled oscillator (VCO) 5 Loop filter (LPF) 6 Vibration sensor 7 Amplifier 8 High pass filter (HPF) 9 Phase amplitude adjuster 10 Voltage adder Sc Control signal Sv Vibration detection signal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J106 AA04 BB10 CC01 CC21 CC38 CC40 CC41 CC52 DD13 EE01 GG01 GG07 HH01 HH03 KK00 KK22 KK39 PP03 QQ06 RR12

Claims (6)

[Claims] An oscillation output of a voltage controlled oscillator is divided by an externally designated division ratio, and the divided output and a reference signal of a reference signal oscillator are input to a phase comparator to detect a phase difference. A PLL-type frequency synthesizer-type oscillation circuit that supplies an oscillation frequency to a voltage-controlled oscillator as a control signal through a loop filter and controls the oscillation frequency. A filter for extracting a component that cannot be absorbed by the PLL itself from components included in the detected vibration detection signal;
Means for canceling a component caused by mechanical vibration included in the control signal by a component extracted by the filter. 2. An oscillation output of a voltage controlled oscillator is divided by an externally designated dividing ratio, and the divided output and a reference signal of a reference signal oscillator are input to a phase comparator to detect a phase difference. A PLL-type frequency synthesizer-type oscillation circuit that supplies an oscillation frequency to a voltage-controlled oscillator as a control signal through a loop filter and controls the oscillation frequency, and detects a vibration received by the voltage-controlled oscillator and outputs a vibration detection signal indicating the oscillation. A filter that extracts a component that cannot be absorbed by the PLL itself from components included in the vibration detection signal, and a component that cannot absorb the component extracted by the filter that can be absorbed by the PLL itself included in the control signal. A phase / amplitude adjuster for adjusting the phase and the phase to be the same level, and an output side of the loop filter provided on the output side of the loop filter, and And a voltage adder for adding the control signal to the voltage-controlled oscillator for output to the voltage-controlled oscillator. 3. The oscillation output of the voltage controlled oscillator is divided by an externally designated dividing ratio, and the divided output and a reference signal of a reference signal oscillator are input to a phase comparator to detect a phase difference. A PLL-type frequency synthesizer-type oscillation circuit that supplies an oscillation frequency to a voltage-controlled oscillator as a control signal through a loop filter and controls the oscillation frequency, and detects a vibration received by the voltage-controlled oscillator and outputs a vibration detection signal indicating the oscillation. A filter that extracts a component that cannot be absorbed by the PLL itself from components included in the vibration detection signal, and a component that cannot absorb the component extracted by the filter that can be absorbed by the PLL itself included in the control signal. A phase-amplitude adjuster for adjusting the phase and the phase to be the same level, wherein the voltage-controlled oscillator includes a plurality of variable capacitors connected in parallel to a resonance circuit. And the control signal is supplied to one of the plurality of variable capacitance elements, and the output signal of the phase and amplitude adjuster is supplied to another one of the plurality of variable capacitance elements. A frequency synthesizer type oscillation circuit characterized by the above-mentioned. 4. The frequency synthesizer type oscillation circuit according to claim 1, wherein said filter is a high-pass filter having characteristics opposite to frequency characteristics of a PLL itself. 5. The frequency synthesizer type oscillation circuit according to claim 1, wherein said filter is a band-pass filter for extracting a specific frequency from components that cannot be absorbed by said PLL itself. 6. The vibration sensor according to claim 1, wherein the vibration sensor is disposed near a resonance circuit of the voltage controlled oscillator, and has the same shape and mass as the resonance circuit.
The described frequency synthesizer type oscillation circuit.