JPH05102726A - Electronically tuned oscillator - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an electronically tuned oscillator, and an object thereof is to provide an electronically tuned oscillator capable of easily adjusting a frequency modulation characteristic. In an electronic tuning oscillator in which a resonance circuit 3 is coupled to a microwave band oscillator 1 so that a first variable capacitance diode 2 is loaded, a transmission line 4 of the first variable capacitance diode 2 is provided. A second variable capacitance diode 5 that is coupled with a fixed coupling amount is provided, and the capacitance is adjusted by the DC bias voltage V ₂ to adjust the frequency modulation characteristic of the electronic tuning oscillator. Further, the transmission line 6 connected to the second variable capacitance diode 5 is provided, and the transmission line 6 is coupled to the transmission line 4 of the first variable capacitance diode 2 at an open end or a side end. Alternatively, the second variable capacitance diode 5 is coupled to the transmission line 4 of the first variable capacitance diode 2 by the component type capacitor 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically tuned oscillator, and more particularly to an electronically tuned oscillator in which a resonance circuit is coupled to a microwave band oscillator so that a first variable capacitance diode is loaded. This kind of electronically tuned oscillator is used as a microwave band voltage controlled oscillator (VCO), a sweep oscillator, an FM modulator, etc., and it is desired to provide an electronically tuned oscillator whose manufacturing and oscillation characteristics can be easily adjusted. Has been done.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a structure of a conventional electronically tuned oscillator, and FIG. 4A is a circuit diagram of the electronically tuned oscillator.
FIG. 4B is an equivalent circuit diagram of the electronic tuning unit. In the figure, 1 is a microwave band oscillator, 11 is an oscillating element composed of an FET or a diode, 12 is a strip conductor (transmission line) of a microstrip line having a dielectric substrate (not shown) and a ground conductor on the back surface, and 3 is a dielectric. A resonance circuit composed of a body disk, 30 is an electronic tuning section, 2 is a varactor diode, and 4 is a transmission line for coupling the varactor diode 2 to the dielectric disk 3.

In FIG. 4A, the dielectric disk 3 is used.
When the resonance frequency of F is ₀ , the f ₀ component on the transmission line 12 is blocked at the coupling point and returns to the oscillating element 11, and the other components are non-reflection terminated by the resistor R. Thus, a signal corresponding to the resonance frequency f ₀ of the dielectric disk 3 is obtained from the oscillator 11. On the other hand, the varactor diode 2 is coupled to the dielectric disk 3 via the transmission line 4, and when the control voltage V ₁ changes, the capacitance C ₁ of the varactor diode 2 changes and the resonance frequency of the dielectric disk 3 changes. f
₀ also changes. Therefore, the capacitance C of the varactor diode 2
I want to obtain the desired frequency modulation characteristics (modulation sensitivity, differential gain, differential phase, etc.) by adjusting the dynamic range of ₁ .

In FIG. 4B, the transmission line 4 is an open end.
Parallel to varactor diode 2 according to stub length l from
Capacity C inserted in₂Acts as. Therefore, this content
Quantity C ₂By finely adjusting the capacitance C of the varactor diode 2₁
You can fine-tune the dynamic range of. Conventionally, transmission line
It was finely adjusted by changing the stub length l of 4. That is,
If you want to extend the transmission line 4, use copper foil on the open end of the transmission line 4.
Soldering and bonding of gold ribbon.
However, according to this method, the heat of the soldering iron and the bonder is removed.
Damage to the varactor diode 2
There is a risk that If you want to shorten the transmission line 4
Is simply cut, but at that time, cut it short.
In many cases, it is too much, and in the end, complicated and dangerous soldering
And bonding work was involved.

[0005]

As described above, in the conventional electronically tuned oscillator, there is no method for adjusting the dynamic range of the varactor diode 2 other than changing the stub length l of the transmission line 4. At the time of manufacturing and adjusting the tuned oscillator, the work is extremely complicated, and the varactor diode 2 may be damaged.

An object of the present invention is to provide an electronically tuned oscillator whose frequency modulation characteristic can be easily adjusted.

[0007]

The above problems can be solved by the structure shown in FIG. That is, the electronic tuning type oscillator of the present invention is an electronic tuning type oscillator in which the resonance circuit 3 is coupled to the microwave band oscillator 1 so that the first variable capacitance diode 2 is loaded. A second variable capacitance diode 5 that is coupled to the two transmission lines 4 with a constant coupling amount is provided.

[0008]

In the electronically tuned oscillator of the present invention, the second variable capacitance diode 5 is coupled in parallel with the first variable capacitance diode 2. Therefore, by adjusting the DC bias voltage V ₂ , the second variable capacitance diode 5
Changes, and this changes in addition to the capacitance of the first variable capacitance diode 2 to change the dynamic range of frequency modulation by the first variable capacitance diode 2.

Also preferably, there is provided a transmission line 6 connected to the second variable capacitance diode 5, the transmission line 6 being coupled to the transmission line 4 of the first variable capacitance diode 2 at an open end or a side end. ing. Further, preferably, the second variable capacitance diode 5 is coupled to the transmission line 4 of the first variable capacitance diode 2 by the component type capacitor 7.

[0010]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. 2A and 2B are diagrams showing the configuration of the electronic tuning oscillator of the embodiment. FIG. 2A is a circuit diagram of the electronic tuning oscillator, and FIG. 2B is an equivalent circuit diagram of the electronic tuning unit. In the figure, 1 is an oscillator, 11 is an oscillating element, 12 is a transmission line, 3 is a resonant circuit composed of a dielectric disk, 20 is an electronic tuning unit, and 2 is a varactor diode (first
Variable capacitance diode), 4 is a transmission line, 5 is a varactor diode (second variable capacitance diode), and 8 is a coupling section.

In FIG. 2A, the varactor diode
The gate 5 is capacitively coupled to the transmission line 4 via the coupling portion 8.
In FIG. 2B, the varactor diode 5 is provided.
As a result, the total of the varactor diode 2 added in parallel
The capacitance Cj has 1 / Cj = 1 / C₂+ 1 / C₃+ 1 / C
_FourHave a relationship. Therefore, the DC of the varactor diode 5
Bias voltage V ₂By adjusting the capacitance C_FourChanges
As a result, the capacitance C of the varactor diode 2 is₂The die
You can fine-tune the dynamic range.

3A and 3B are views showing the configuration of another electronic tuning section of the embodiment. FIG. 3A shows the open end of the transmission line, and FIG. 3B shows the side end of the transmission line. 3C shows the case where the varactor diodes 5 are respectively coupled by the component type capacitors. In FIG. 3A, 6 is the transmission line of the varactor diode 5, and the impedance Z of the line at the distance d from the open end of the coupling portion 8 is Z = −jZ.
It is represented by ₀ cot βd. However, Z ₀ is the characteristic impedance of the transmission line 6, and β is the phase constant (2π / λ).
Therefore, for example, by selecting this distance d in such a range that the transmission line 6 becomes capacitive, a capacitance is inserted in series in this portion, whereby the varactor diode 5 is formed.
The influence of the capacitance change on the varactor diode 2 due to the capacitance change can be suppressed.

As shown in FIG. 3B, the connecting portion is shown.
8 may consist of side ends facing transmission lines 4 and 6.
For example, the coupling capacitance C of this part₃Can be relatively large. Servant
In this case, the varactor diode 2
The contribution amount of the diode 5 can be increased. Figure 3 (C)
7 is a component type capacitor, and in general, this part
The capacitance value of the product type capacitor 7 can be variously selected. Therefore,
According to the above method, the capacitance C of the coupling portion 8 ₃Can be set to any value
There is an advantage.

[0014]

As described above, according to the present invention, in the electronic tuning oscillator in which the resonance circuit 3 is coupled to the microwave band oscillator 1 so that the first variable capacitance diode 2 is loaded, Since the second variable capacitance diode 5 that is coupled to the transmission line 4 of the variable capacitance diode 2 of FIG. 2 with a constant coupling amount is provided, the desired frequency of the electronic tuning oscillator is adjusted by adjusting the DC bias voltage V _2. Modulation characteristics can be easily obtained. Therefore, there is no need to use a soldering iron, a bonder or the like as in the conventional case, and there is no risk of degrading or damaging the variable capacitance diode 2.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a diagram showing a configuration of an electronically tuned oscillator according to an embodiment.

FIG. 3 is a diagram showing a configuration of another electronic tuning unit of the embodiment.

FIG. 4 is a diagram showing a configuration of a conventional electronically tuned oscillator.

[Explanation of symbols]

 1 Oscillator 2,5 Variable capacitance diode 3 Resonance circuit 4,6 Transmission line

Claims (3)

[Claims] 1. An electronic tuning type oscillator in which a resonance circuit (3) is coupled to a microwave band oscillator (1) so that a first variable capacitance diode (2) is loaded therein. An electronically tuned oscillator characterized in that a second variable capacitance diode (5) is coupled to the transmission line (4) of (2) with a constant coupling amount. 2. A transmission line (6) connected to a second variable capacitance diode (5), said transmission line (6) being relative to the transmission line (4) of the first variable capacitance diode (2). The electronically tuned oscillator according to claim 1, wherein the electronically tuned oscillator is coupled at an open end or a side end. 3. The second variable capacitance diode (5) is first
2. The electronically tuned oscillator according to claim 1, wherein said variable capacitance diode (2) is connected to said transmission line (4) by a component type capacitor (7).