JPS59158108A - Variable phase difference oscillator - Google Patents

Abstract

PURPOSE:To widen the variable range of the phase difference between a voltage- controlled oscillator and a reference oscillator and to facilitate the size reduction and integration of a circuit by detecting the phase difference through a multiplying circuit and comparing it with a reference voltage. CONSTITUTION:When the output signal of the 1st oscillator 1 is v1=k1cosomegat and the output signal of the 2nd oscillator 12 is v2=k2cos(omegat+theta), they are applied to a multiplying circuit 8 through branching circuits 2 and 7 and the multiplying circuit 8 outputs a signal v0=kv1.v2kk1k2cosomegat.cos(omegat+theta)=V2kk1k2(cos (2omegat+theta)+costheta), where (k), k1, and k2 are proportional constants. A lowpass A lowpass filter 9 extracts a signal with an amplitude proportional to costheta from said output signal. This output is compared with the set voltage at a terminal 11 by a comparing circuit 10 and the result is applied to the control input of the voltage-controlled oscillator 12 to control the pahse difference theta corresponding to the set voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a circuit that generates two sine wave signals having a preset phase difference. The circuit of the invention is suitable, for example, as an excavator for composite phase adjustment in a space-diaperity radio communication device.

[Description of prior art]

A conventional circuit of this type is constructed as shown in FIG. In the figure, 1 is an oscillator, 2 is a branch circuit, 3 and 4 are output terminals, 5a and 5b are capacitors, and 6 is an inductor. In this circuit, a signal from an oscillator 1 is branched into two by a branch circuit 2, and one branched signal is supplied to an output terminal 3. On the other hand, the other output signal of branch circuit 2 is connected to capacitor 5.
a, 5b and an inductor 6. By changing the constants of the capacitors 5a, 5b and the inductor 6, the phase difference between the output terminals 4 and 3 can be controlled.

However, this circuit has a drawback that the variable range of the phase difference between the output terminals 3 and 4 is narrow because the variable range of the capacitor and inductor is limited. In addition, since capacitors and inductors are included in the circuit elements, the circuit can be made smaller and
The drawback was that it was difficult to integrate.

[Purpose of the invention]

The present invention eliminates these drawbacks, allows the phase difference between two output signals to be varied over a wide range, and enables monolithic I
It is an object of the present invention to provide a variable phase difference oscillator with a circuit configuration suitable for C conversion.

[Features of the invention]

The present invention includes a first oscillator that generates a reference signal, and a second oscillator that generates a signal of the same frequency as that of the oscillator and whose output signal phase is voltage controlled. The output signal of the second oscillator is mixed with the output signal of the second oscillator, a low frequency component is extracted from this mixed output, this low frequency component is compared with a set voltage, and the signal phase of the second oscillator is controlled by this comparison output. It is characterized by being configured.

[Explanation based on examples]

FIG. 2 is a block diagram of a circuit according to a first embodiment of the present invention.

A first oscillator 1 generates a sine wave with a reference frequency ro.

The second oscillator 12, whose output is branched into two by the first branch circuit 2, is a voltage-controlled oscillator that generates a signal with a river wave number fo, and whose output is branched into two by the second branch circuit 7.
Branched out. First branch circuit 2 and second branch circuit 7
The outputs of each of the -powers are respectively applied to two inputs of a multiplier circuit 8, and the output of the multiplier circuit 8 is led via a low-pass filter 9 to one input of a comparator circuit 10. It is guided to one input of this comparator circuit 10. The other input terminal 11 of this comparison circuit 10 is given a set voltage for determining the output signal phase difference. The output of the comparison circuit 10 is applied to the control input of the second oscillator 12.

To explain the operation of such a circuit, if the output signal of the first oscillator 1 is VL = ks cos ω and the output signal of the second oscillator 12 is V2 = 2 cos (ωt + θ), then the output of the multiplier circuit 8 is The following signal is obtained: VO==kvl-v2=kklk2cosωt-cos(ωt+θ). However, 1 and k2 are constants of proportionality. From this signal, a low-pass filter 9 can extract a signal with an amplitude proportional to cos θ. When this output is compared with the set voltage of the terminal 11 by the comparison circuit IO and applied to the control input of the voltage-controlled oscillator 12, the phase difference θ can be controlled according to this set voltage.

FIG. 3 shows the output voltage of the low-pass filter 9 with respect to the phase difference θ between the first oscillator 1 and the second oscillator 12.

That is, for example, when the initial state is the point shown in the figure and a DC component higher than the reference voltage is generated, an even higher control voltage is applied to the voltage-controlled oscillator 12. Here, when there is a positive relationship between the control voltage of the voltage-controlled oscillator 12 and the oscillation frequency, the oscillation frequency increases and the phase difference θ is expanded, and the phase difference θ changes to the equilibrium point at point a. Similarly, when the initial state is at the 0 point, the oscillation frequency of the voltage-controlled oscillator 12 decreases, and the phase difference θ decreases to the equilibrium point a. In this way, the phase difference θ can be adjusted from 0° to 1 using the reference voltage.
It can be controlled up to 80°.

FIG. 4 is a configuration diagram of a second embodiment of the present invention. In the figure, 13 is a bipolar comparator. 14 is a polarity control terminal of the bipolar comparator 13. The rest is the same as the embodiment shown in FIG.

In this embodiment, when the voltage applied to the polarity control terminal 14 makes the bipolar comparator 13 positive, the same operation as in the embodiment of FIG. 2 is performed. Further, when the bipolar comparator is made negative by the polarity control terminal 14, the voltage-controlled oscillator 12 is controlled in the opposite manner to the embodiment shown in FIG. Control θ. That is, by the voltage applied to the reference voltage terminal 11 and the polarity control terminal 14,
Any phase difference θ between 0° and 360° can be obtained.

-1- In the example, the low-pass filter 9 is placed on the input side of the comparator 13, but the same result of 9J can be obtained even if the filter 9 is placed on the output side of the comparator 13.

Next, each element when configuring the relationship shown in the above example into a monolithic IC will be explained.

FIG. 5 is a diagram showing an example of the configuration of the multiplication circuit 8. Transistor Q1 acts as a grounded emitter amplifier;
The collector circuit of transistor Q2 is connected in parallel to the output load R. With this configuration, from input 11 to output OU
The gain of the signal leading to T will change depending on the signal of the human force I2, and a signal of the product of the two human forces 11 and I2 is obtained at the output OUT.

In addition, the multiplier circuit 8 can be easily formed by a diode to which an appropriate bias voltage is applied.

FIG. 6 is a diagram showing an example of the configuration of the low-pass filter 9. A monolithic IC type operational amplifier A1 and a capacitor C1
Negative feedback is applied to form an integrating circuit. Also, a CR low-pass filter is formed in the input circuit of this operational amplifier A1 by a resistor R2 and a capacitor C2. The transmission characteristics from the input IN to the output OUT of this circuit are those of a low-pass filter.

Furthermore, branch circuits 2 and 7 can be resistive branches or direct branches.

By using such elements, the circuit of the present invention can be constructed using a monolithic IC.

Multiplier circuit 8, low-pass filter 9 and branch circuit 2.7 described above
This configuration is merely an example, and the present invention can be implemented using various circuits other than those illustrated here.

[Explanation of effects]

As explained above, according to the present invention, the phase difference between the voltage-controlled oscillator and the reference oscillator is detected by a multiplication circuit, and this is compared with the reference voltage, so that the phase difference can be controlled over a wide range. There are advantages. Further, since the circuit does not include an inductor or a large capacitor, there is an advantage that the circuit can be easily miniaturized and integrated. The circuit of the present invention was useful when implemented in an oscillator for adjusting the composite phase of a space diversity wireless communication device.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional signal generation circuit. FIG. 2 is a circuit diagram of the first embodiment of the present invention. FIG. 3 is an explanatory diagram of the operation. The horizontal axis shows the output phase difference of both total oscillators, and the vertical axis shows the output voltage of the low-pass filter. FIG. 4 is a circuit diagram of a second embodiment of the present invention. FIG. 5 is a diagram showing an example of the configuration of a multiplication circuit. FIG. 6 is a diagram showing an example of the configuration of a low-pass filter. DESCRIPTION OF SYMBOLS 1... First oscillator that generates a reference signal, 2... Branch circuit, 3.4... Output terminal, 5a, 5b... Capacitor, 6... Inductor, 7... Branch circuit , 8・
...Multiplier circuit, 9...Low-pass filter, 10...Comparison circuit, 11...Input terminal for giving set voltage, 12...
Voltage-controlled second oscillator, 13... bipolar comparator,
14...Polarity control terminal. Patent Applicant Nippon Telegraph and Telephone Public Corporation Agent Patent Attorney Nao Takashi Ide'M2 Roman 3 Figure z Roman 4I121

Claims (1)

[Claims] (11) A first oscillator that generates a reference signal, a first branch circuit that branches the output of the first oscillator into two, and a second oscillator configured to generate a signal whose output signal phase changes depending on the input voltage; a second branch circuit that branches the output of the second oscillator into two; and one of the first branch circuits. an it) multiplication circuit that receives the output and one output of the second branch circuit as two inputs; a low-pass filter that extracts a low-frequency signal component from the output of this multiplication circuit; and an output of this low-pass filter. a comparator circuit having one input of the oscillator and a set voltage given to the other input, the output signal of the second oscillator is controlled by the output signal of the comparator circuit, and the first oscillator A variable phase difference oscillator characterized in that the outputs of the other of the branch circuit and the second branch circuit are respectively guided to two output terminals.