JPS63309002A - Voltage-controlled oscillator - Google Patents

Abstract

PURPOSE:To easily vary an oscillation frequency band by using the same substrate by connecting 1st and 2nd tip open stubs to a microstrip line at an interval of nearly 1/4 wavelength. CONSTITUTION:The tip open stubs 13a and 13b are connected to the microstrip lines 5a between the gate terminal 8 to a field effect transistor FET 7 and the anode terminal 3 of a varactor diode 1 at two positions which are at an intervals of nearly 1/4 wavelength. Then the stubs at the positions are adjusted finely in length. The electric length between the anode terminal 3 of the varactor diode 1 and the gate terminal 8 of the FET 7 can be varied by the fine adjustment. This is equivalent to variation in the electric length of the microstrip line 5a, so the oscillation frequency band of a voltage-controlled oscillator can be varied by adjusting the stubs finely even when the same substrate is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to lowering the cost of a voltage controlled oscillator (hereinafter abbreviated as VCO).

[Conventional technology]

Here, a field effect transistor (
[Hereinafter, it will be abbreviated as PET] as an example.

Figure 4 is the Journal of the Institute of Electronics and Communication Engineers, vol. 568-C.
.

This is an example of the configuration of a conventional VCO shown on pages 56 to 1158 of the December issue of A12. The cathode terminal of the diode (1), (3) is the anode terminal of the variable capacitance diode (1), and (41 is the resistor).

+51 iO microstrip line, (6; is a capacitor.

(7) is FET, +81 is FET +71's gate 1 child, (9) is FIT (source terminal of 71, αGi'j
F K T +71 drain terminal, (11 is a tuning voltage application terminal, (11b) is a drain voltage application terminal, (11C) is a high frequency output terminal, and α2 is a bias circuit.

In Figure 4, the variable capacitance diode (11 cathode terminals)
2) The capacitor (6aJ) is grounded.

In addition, the direct current tuning voltage is applied to the I terminal (11b).The anode terminal (31) of the Machitomoya diode (1)
ij resistance (4a,) 7 microstrip line (5b
) and is grounded via a bias circuit (12a). Therefore, when a positive voltage is applied to the same voltage application terminal (11a), the inter-terminal capacitance of the variable capacitance diode (1) can be varied by a positive value. The drain terminal toi of FET (71) is grounded at high frequency with a capacitor (6b).

In terms of direct current, it is connected to the drain voltage application terminal (11b). Also, the gate I (8) of Fl!:T (71 is grounded via the bias circuit (12), and connected to the source terminal (9).
) is grounded via a bias circuit (12b). VCO
In order to oscillate, the drain voltage application terminal (11
Applying a positive drain voltage to b). At this time, FET (
The gate 'H voltage of 7) is determined by the drain current i and the resistance (4
It is determined by the voltage value that drops in b). Then, by connecting the load between the high frequency output terminal (11C,) and the ground conductor, the ^-frequency oscillation output is output to the load.

F K T The reflection coefficient when looking at the variable '8 mouse diode (1) side from the gate terminal (8:) of f7+ is r,, FK
If the reflection coefficient when looking at F K T t71 from the gate terminal (8) of Tf71 is rl, the oscillation condition is satisfied at a frequency that simultaneously satisfies the linear equation.

17”+l > II/Fzl ii
+Lr, -△(1/r2) j2
+Oscillation frequency (4, determined by the phase condition of the second equation.The following explanation (J, Electric) will be made assuming that the vibration condition of the first equation is satisfied.

This is because lrl can be changed by changing the capacitance between the terminals of the variable capacitance diode (1) using the tuning voltage applied to the 111-tonne voltage application terminal (11a).

The oscillating station mantissa of the VCO is the tuning voltage 1 (more variable).

FIG. 5 shows a diagram for explaining the excavated frequency range in a VCO having a conventional configuration. l-r indicated by a solid line in Fig. 5,
The oscillation frequency of the VCO given by the intersection of 1-(1//'2), indicated by one point aS, is the tuning voltage.

For example, from Ov to (1) Vl, the frequency changes from fc to fH.

[Problems with trying to invent or exploit]

In the conventional m-structure VCO shown in FIG. 4, the microstrip line (5a
) It was necessary to create boards with different lengths. An eye, an expensive etching mask, or a printing screen is required to create the substrate. Therefore, there was a problem that the unit price of the VCO board became expensive.

This invention solves this problem by using the same substrate. 9 oscillation frequency bands even if used? Easily changeable VCO
The goal is to get a 9.

[Means for resolving the problem W4] The VCO according to this invention has the gate terminal (81) of the FET t71 and the anode terminal (81) of the variable capacitance diode (1).
A microstrip line (5a) lζ between 31 and 31, with an open-ended stub connected to two locations approximately 1/4 wavelength apart, was constructed.

[Effect]

The VCO in this invention tζ finely adjusts the length of two stubs connected to the microstrip line (5a) approximately 1/4 wavelength apart according to one oscillation band.

, By this fine adjustment 1, it is possible to change the electrical length between the anode terminal (31) and the gate terminal (8) of the variable capacitance diode il+. This is equivalent to changing the electrical length, so even if the same board is used, the oscillation frequency band of the VCO can be changed by just one fine adjustment of the stub.As a result, several types of VCO boards can be made common, and expensive Since the mask or screen can be reduced, VCO
The unit price of the board can be reduced.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a VCO according to the present invention, in which the same or corresponding parts as in the fourth case are denoted by the same reference numerals. In Figure 1, α
3 (This is a stub with an open end. The stubs (13a), stubs (13t), and l have the same dimensions, and are provided at approximately 174 wavelength intervals on the microstrip line (5a). (131)) in two locations approximately 1/4 wavelength apart is based on the tuning voltage.
Approximately, the variable capacitance diode (1) and the gate terminal (81
It is possible to change the electrical length between. This stub (13a
), (13s 5 microstrip line (5aJ
Added to the electrical length of n' - electrical length Δθ [rad] f; 4
It can be approximated by the following formula.

Δθ = 2t, anβ1 (31 In the third equation, βl is the open-ended stub (13a), (+3b
) Electrical length per piece, Zi! Open-ended stub (13
Characteristic impedance of a), (13b), z,)
f: Characteristic impedance of the J microstrip line (5a).

When such stubs (13a) and (13b) are provided.

The oscillation condition is satisfied at a frequency that satisfies the following equation.

Lr, -2AfJ = L(1/r2) +
4, but LI'112. Stub (13a
,).

When the length of (15b) is 1koi, from the gate terminal (8) of FET17+ to the variable capacity heavy diode (1) 111
This is the reflection phase when looking at 1. In the fourth formula, the stub (13a)
, (13b) changes Δθ, so even if the same ΔI゛1, it is possible to change the frequency that satisfies the firing number condition. FIG. 2 - A diagram for explaining the oscillation frequency range in the present invention is shown. In Figure 2, CLr
+ -2AO) c! -L (1/r2) The oscillation frequency of the intersection point error t'L vco is the stub (15a,
), (13b) varies depending on the electrical length βl. Electrical length β
The excavation frequency range for l is shown in Figure 3. Is the oscillation frequency the longer βl is? You can lower it.

In addition, in the above embodiment, an active half-body element is used.

I explained it with FET, or bipolar transistor.

S-T, other three-terminal element chairs may be used,
Further, it may be a Gunn diode, an Invat diode, or any other two-terminal negative resistance element.

〔Effect of the invention〕

As described above, this invention jζyon has a stub (13aJ
By changing the electrical length βl of (15b), the oscillation frequency range of the VCO can be varied. Therefore, the vco using the same board
Alternatively, by finely adjusting the stubs (15a) and (1sb), different oscillation frequency ranges can be accommodated. Therefore, the substrates of several types of VCOs with different required oscillation frequency ranges are made common, and a high ftm etching mask or printing screen mbtm is used.

The cost of the VCO board can be reduced.

[Brief explanation of drawings]

The first figure is a configuration diagram of a VCO based on an IC according to an embodiment of the present invention, FIG. A characteristic diagram showing the oscillation frequency with respect to the electrical length βl In of the VCO stub, FIG. 4 is a configuration diagram of a conventional VCO,
Figure 5 is a characteristic diagram for explaining the frequency range of conventional VC:O (1). In the figure, (1) is a variable capacitance diode, (4I is a resistor, (
51 is a microstrip line, (6, f; f capacitor, (7) is an FBT, and a +131 male tab. +PJ- or equivalent parts in the figure indicate the same symbols.

Claims (2)

[Claims] (1) Consists of a variable capacitance diode, a microstrip line connected to one end of the variable capacitance diode, and an active semiconductor element connected to the other end of the microstrip line, and oscillates by the voltage applied to the variable capacitance diode. A voltage controlled oscillator capable of variable frequency, characterized in that a first stub with an open end and a second stub with an open end are connected to the microstrip line at approximately 1/4 wavelength intervals. (2) The voltage controlled oscillator according to claim 1, characterized in that a field effect transistor is used as the active semiconductor element.