JP2004312104A - Voltage controlled oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widen an oscillation frequency range by suppressing the deterioration of the phase noise characteristics. <P>SOLUTION: A microstrip line forming a resonance circuit is divided into two microstrip lines 11, 12, and a variable-capacitance element 22 and a coupling capacitor 33 are connected in parallel to the division point of the divided microstrip lines 11, 12 to feed the variable capacitance element 22 with a frequency adjusting bias voltage through a bias feed circuit 52. The coupling capacitor 33 is so set to a capacitance value that its reactance is smaller enough than the characteristic impedance of the microstrip line, and that a specified variation quantity of the total capacitance value is obtained with the change of the capacitance value of the element 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a voltage controlled oscillator, and more particularly, to a wider oscillation frequency of a voltage controlled oscillator including a transmission line and a variable capacitance element formed on a substrate in a resonance circuit.
[0002]
[Prior art]
As shown in FIG. 5, for example, a conventional voltage controlled oscillator includes a half-wavelength microstrip line 10, a variable capacitance element 21 connected to one end of the microstrip line 10 through a coupling capacitor 31, and a variable capacitance element. A bias supply circuit 51 for supplying a control voltage to the element 21 and a negative resistance circuit 61 connected to the other end of the microstrip line 10 via a coupling capacitor 32 are provided.
[0003]
Here, the bias supply circuit 51 is a circuit element exhibiting a high impedance with respect to the oscillation frequency, for example, a 波長 wavelength, in order to supply a control voltage to the variable capacitance element 21 without affecting the resonance circuit. Consists of a strip line and a high-frequency bypass capacitor. (For example, refer to Patent Document 1.)
[Patent Document 1]
JP 2001-244742 A
[Problems to be solved by the invention]
In the above-described conventional example, the oscillation frequency range varies due to the variation in the characteristics of the coupling capacitor and the variable capacitance element and the variation in the dielectric constant of the dielectric substrate forming the microstrip line. It is necessary to perform trimming adjustment and the like.
[0005]
In order to eliminate the adjustment of the oscillation frequency due to such a variation in the components, the coupling capacitor is increased in capacity to strengthen the coupling between the variable capacitance element and the microstrip line, and the frequency change with respect to the control voltage applied to the variable capacitance element. That is, the oscillation frequency range may be widened by increasing the modulation sensitivity.
[0006]
However, generally, increasing the modulation sensitivity deteriorates the phase noise characteristic. Also, if the oscillation frequency range is widened only by changing the capacitance of the variable capacitance element, the modulation sensitivity tends to decrease as the control voltage increases, and the oscillation frequency does not change linearly with the control voltage. Have a point.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a voltage-controlled oscillator that can suppress the deterioration of phase noise characteristics and widen the oscillation frequency range, and can eliminate trimming adjustment of a microstrip line due to variation in components.
[0008]
[Means for Solving the Problems]
A voltage controlled oscillator according to the present invention is a voltage controlled oscillator including a microstrip line formed on a substrate and a variable capacitance element supplied with a control voltage in a resonance circuit, wherein the microstrip line is divided into a plurality of divided microstrip lines. A coupling capacitor and a variable capacitance element to which a bias voltage for frequency adjustment is supplied are connected in parallel between the strip lines.
[0009]
Specifically, a １ ／ wavelength microstrip line formed on a substrate, a variable capacitance element connected to one end of the 波長 wavelength microstrip line and supplied with a control voltage, In a voltage controlled oscillator having a negative resistance circuit connected to the other end of the wavelength microstrip line, the half-wavelength microstrip line is divided into two at the center, and one end of one of the two divided microstrip lines is provided at one end. A variable capacitance element to which the control voltage is supplied is connected via a coupling capacitor, the negative resistance circuit is connected to one end of the other divided microstrip line, and a coupling capacitor is provided between the divided microstrip lines. And a variable capacitance element to which a bias voltage for frequency adjustment is supplied is connected in parallel.
[0010]
A half-wavelength microstrip line formed on a substrate; a variable capacitance element connected to one end of the half-wavelength microstrip line and supplied with a control voltage; A voltage-controlled oscillator having a negative resistance circuit connected to the other end of the line, dividing the microstrip line into three, and connecting the variable capacitance element to a first divided outer microstrip line via a coupling capacitor. And the negative resistance circuit is connected to an outer third microstrip line divided into three parts, between the intermediate second microstrip line divided into three parts and the first and third microstrip lines. Are connected in parallel with a coupling capacitor and a variable capacitance element to which a bias voltage for frequency adjustment is supplied.
[0011]
Furthermore, the first and second microstrip lines divided into three and the first and third microstrip lines outside of the three divided half wavelength microstrip lines are respectively connected. Connected in parallel between the negative resistance circuit of the first embodiment and the intermediate second microstrip line of the three-divided half-wavelength microstrip lines and the first and third microstrip lines. A push-push type voltage controlled oscillator can be configured by having a capacitor and a variable capacitance element to which a control voltage is supplied, and combining and outputting the oscillation output signals of the first and second negative resistance circuits. .
[0012]
The coupling capacitor connected to the divided part of the microstrip line has a reactance sufficiently smaller than the characteristic impedance of the microstrip line, and a capacitance value during operation of the variable capacitance element connected in parallel. Is set so that a predetermined amount of change is obtained in the total capacitance value with respect to the change in
[0013]
Further, a high-frequency diode such as a PIN diode may be used instead of the variable capacitance element connected between the divided microstrip lines, or a coplanar line may be used instead of the microstrip line.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a block diagram showing a first embodiment of the present invention, in which the same components as those of the conventional example shown in FIG.
[0016]
In FIG. 1, the microstrip lines 11 and 12 divided into two, a first variable capacitance element 21 connected to one end of one of the microstrip lines 11 via a coupling capacitor 31, A first bias supply circuit 51 for supplying a control voltage to the variable capacitance element 21 of
A negative resistance circuit 61 connected to one end of the other divided microstrip line 12 via a coupling capacitor 32; and a second variable capacitance connected to the divided portions of the microstrip lines 11 and 12. An element 22, a coupling capacitor 33 connected in parallel to the second variable capacitance element 22, a second bias supply circuit 52 for supplying a frequency adjustment bias voltage to the second variable capacitance element 22, And a high impedance circuit element 41 for grounding the frequency adjustment bias voltage supplied to the second variable capacitance element 22.
[0017]
Here, the first and second bias supply circuits 51 and 52 have the same circuit configuration. In order to supply a control voltage or a frequency adjustment bias voltage to the variable capacitance elements 21 and 22 without affecting the resonance circuit. A high-frequency bypass capacitor and a circuit element (for example, a quarter-wave strip line) that exhibits a high impedance with respect to the oscillation frequency and allows a DC component to pass therethrough.
[0018]
The high-impedance circuit element 41 is, for example, a quarter-wave strip line that presents a high impedance with respect to the oscillation frequency and passes a DC component.
[0019]
The microstrip lines 11 and 12 are obtained by dividing a 波長 wavelength microstrip line at the center, and are 波長 wavelength microstrip lines.
[0020]
A second variable capacitance element 22 and a coupling capacitor 33 are connected in parallel between the microstrip lines 11 and 12. The capacitance of the coupling capacitor 33 is set so that its reactance is sufficiently smaller than the characteristic impedance of the microstrip line, and the total capacitance of the second variable capacitance element 22 during operation is changed. The value is set so as to obtain a predetermined change amount.
[0021]
By setting the capacitance value of the coupling capacitor 33 in this way, the divided microstrip lines 11 and 12 can function equivalently as a half-wavelength microstrip line, and the modulation of the second variable capacitance element 22 can be performed. It is possible to suppress the deterioration of the phase noise characteristic by reducing the sensitivity.
[0022]
FIG. 2 is a diagram illustrating a change in impedance of the resonance circuit viewed from the negative resistance circuit 61 when the capacitance value of the second variable capacitance element 22 is changed.
[0023]
Here, the capacitance value of the first variable capacitance element 21 is fixed, and the resonance center frequency is 5 GHz.
[0024]
As shown in FIG. 2, when the capacitance value is increased by changing the frequency adjustment bias voltage supplied to the second variable capacitance element 22, the electrical length of the microstrip line becomes equivalently shorter, so that the resonance frequency becomes higher. Become.
[0025]
That is, by adjusting the capacitance value of the second variable capacitance element, the electrical length of the microstrip line can be equivalently adjusted. If the oscillation frequency is controlled by the control voltage supplied to the first variable capacitance element, the deterioration of the phase noise characteristic can be suppressed and the oscillation frequency range can be widened, and the trimming adjustment of the microstrip line due to the variation of the components can be performed. Can be eliminated.
[0026]
FIG. 3 is a block diagram showing a second embodiment of the present invention.
[0027]
Here, the difference from the embodiment shown in FIG. 1 is that the microstrip line is divided into three parts, and a variable capacitance element and a coupling capacitor are connected in parallel at each division. The same components as those shown in FIG. 1 are denoted by the same reference numerals.
[0028]
In FIG. 3, the microstrip lines 13, 14, 15 divided into three, a first variable capacitance element 21 connected to one end of the microstrip line 13 through a coupling capacitor 31, and a first variable capacitance element 21, A first bias supply circuit 51 for supplying a control voltage to the variable capacitance element 21, a negative resistance circuit 61 connected to one end of the divided microstrip line 15 via the coupling capacitor 32,
A second variable capacitance element 22 connected to the division point of the microstrip lines 13 and 14, a coupling capacitor 33 connected in parallel to the second variable capacitance element 22, and a division point of the microstrip lines 14 and 15; , A coupling capacitor 34 connected in parallel with the third variable capacitance element 23, and the second and third variable capacitance elements 22 via the microstrip line 14. , 23, a high bias circuit element 41 for grounding the bias voltage supplied to the second variable capacitance element 22, and a third bias supply circuit 52 for supplying a frequency adjustment bias voltage to the second variable capacitance element 22. And a high impedance circuit element 42 for grounding a bias voltage supplied to the variable capacitance element 23.
[0029]
Here, the microstrip lines 13, 14, 15 are obtained by dividing a half-wavelength microstrip line into three.
[0030]
The coupling capacitors 33 and 34 connected in parallel with the variable capacitance elements 22 and 23 between the divided microstrip lines are set so that the reactance is sufficiently smaller than the characteristic impedance of the microstrip line. At the same time, the total capacitance value is set so as to obtain a predetermined amount of change with respect to a change in the capacitance value of the variable capacitance elements 22 and 23 during operation.
[0031]
As described above, the microstrip line is divided into three parts, the variable capacitance element and the coupling capacitor are connected in parallel to the divided parts, and the bias voltage for frequency adjustment is supplied, so that the frequency is more variable than when the microstrip line is divided into two parts. The range can be expanded.
[0032]
FIG. 4 is a block diagram showing a third embodiment of the present invention.
[0033]
Here, the difference from the embodiment shown in FIG. 3 is that a push-push type voltage controlled oscillator is used. The same components as those shown in FIG. 3 are denoted by the same reference numerals.
[0034]
Note that a push-push type oscillator has the same negative resistance circuit placed at both ends of a resonance circuit, synthesizes fundamental waves output from each negative resistance circuit in opposite phases, and synthesizes the second harmonic in phase. By doing so, the oscillator can efficiently extract the second harmonic.
[0035]
In FIG. 4, the microstrip lines 13, 14, 15 divided into three, a first negative resistance circuit 61 connected to one end of the microstrip line 15 via the coupling capacitor 32, A second negative resistance circuit 62 connected to one end of the divided microstrip line 13 via a coupling capacitor 33,
First and second variable capacitance elements 22 and 23 connected to the divided portions of microstrip lines 13, 14 and 15, respectively, in parallel with the first and second variable capacitance elements 22 and 23. Coupling capacitors 33 and 34 connected to each other; a bias supply circuit 52 for supplying a control voltage to the first and second variable capacitance elements 22 and 23 via the microstrip line 14; And high-impedance circuit elements 41 and 42 for grounding the control voltages supplied to the variable capacitance elements 22 and 23, respectively.
[0036]
Here, the microstrip lines 13, 14, 15 are obtained by dividing a half-wavelength microstrip line into three.
[0037]
The coupling capacitors 33 and 34 connected in parallel with the variable capacitance elements 22 and 23 between the divided microstrip lines are set so that the reactance is sufficiently smaller than the characteristic impedance of the microstrip line. Are set so that a predetermined amount of change is obtained in the total capacitance value with respect to a change in the capacitance value of the variable capacitance elements 22 and 23 during operation.
[0038]
In this way, the microstrip line is divided into three parts, and the variable capacitance element and the coupling capacitor are connected in parallel to the divided parts to constitute a push-push type voltage controlled oscillator, thereby suppressing the deterioration of the phase noise characteristic and changing the frequency. The range can be expanded.
[0039]
Here, the microstrip line is divided into three to constitute the push-push type voltage controlled oscillator, but may be divided into three or more.
[0040]
Also, in the first and second embodiments, it is apparent that the same effect can be obtained even if the microstrip line is divided into three or more.
[0041]
Furthermore, in the first and second embodiments, a high-frequency diode such as a PIN diode may be used instead of the variable capacitance element connected to the divided portion of the microstrip line, and a coplanar line may be used instead of the microstrip line. It is apparent that the same effect can be obtained even if the above configuration is adopted.
[0042]
【The invention's effect】
As described above, according to the present invention, the microstrip line forming the resonance circuit of the voltage controlled oscillator is divided into a plurality of parts, and the variable capacitance element and the coupling capacitor are connected in parallel to the divided parts, respectively, so that the phase noise characteristic is improved. And the oscillation frequency range can be widened by suppressing the deterioration of the microstrip line due to the variation of the components.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram showing a change in impedance of a resonance circuit viewed from a negative resistance circuit 61 when a capacitance value of a second variable capacitance element 22 shown in FIG. 1 is changed.
FIG. 3 is a block diagram showing a second embodiment of the present invention.
FIG. 4 is a block diagram showing a third embodiment of the present invention.
FIG. 5 is a block diagram showing a conventional example.
[Explanation of symbols]
11, 12, 13, 14, 15 Microstrip lines 31, 32, 33, 34 Coupling capacitors 61, 62 Negative resistance circuits 21, 22, 23 Variable capacitance elements 51, 52 Bias supply circuits 41, 42 High impedance circuit elements

Claims (7)

In a voltage controlled oscillator including a microstrip line formed on a substrate and a variable capacitance element supplied with a control voltage in a resonance circuit, the microstrip line is divided into a plurality, and a coupling capacitor is provided between the divided microstrip lines. A voltage-controlled oscillator, wherein a variable capacitance element to which a bias voltage for frequency adjustment is supplied is connected in parallel. A half-wavelength microstrip line formed on a substrate, a variable capacitance element connected to one end of the half-wavelength microstrip line and supplied with a control voltage; A voltage-controlled oscillator having a negative resistance circuit connected to the other end,
The half-wavelength microstrip line is divided into two at the center, and a variable capacitance element to which the control voltage is supplied via a coupling capacitor is connected to one end of one of the two divided microstrip lines, and is divided into two. The negative resistance circuit is connected to one end of the other microstrip line, and a coupling capacitor and a variable capacitance element supplied with a bias voltage for frequency adjustment are connected in parallel between the two divided microstrip lines. A voltage controlled oscillator. A half-wavelength microstrip line formed on a substrate, a variable capacitance element connected to one end of the half-wavelength microstrip line and supplied with a control voltage; A voltage-controlled oscillator having a negative resistance circuit connected to the other end,
The microstrip line is divided into three, the variable capacitance element is connected to a third divided outer microstrip line via a coupling capacitor, and the negative third divided microstrip line is connected to the outer third microstrip line. A variable resistance element to which a coupling resistor and a frequency adjustment bias voltage are supplied between the intermediate second microstrip line divided into three and the first and third microstrip lines, and Are connected in parallel, respectively. A half-wave microstrip line divided into three, and first and second negative electrodes connected to first and third microstrip lines outside of the half-wave microstrip line divided into three, respectively. A resistive circuit, a coupling capacitor connected in parallel between an intermediate second microstrip line among the three-divided half-wavelength microstrip lines and the first and third microstrip lines, and A voltage-controlled oscillator having a variable capacitance element supplied with a control voltage, and combining and outputting the oscillation output signals of the first and second negative resistance circuits. The reactance of the coupling capacitor connected to the divided portion of the microstrip line is sufficiently smaller than the characteristic impedance of the microstrip line, and the change of the capacitance value during operation of the variable capacitance element connected in parallel. 5. The voltage controlled oscillator according to claim 1, wherein the total capacitance value is set so that a predetermined change amount is obtained. 6. The voltage controlled oscillator according to claim 1, wherein a high frequency diode such as a PIN diode is used instead of the variable capacitance element connected between the divided microstrip lines. 7. The voltage controlled oscillator according to claim 1, wherein a coplanar line is used instead of the microstrip line.

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