JPS6154704A - Microwave oscillator - Google Patents

Abstract

PURPOSE:To remove the influence of variance among elements, to adjust an oscillation frequency to a constant value accurately, and to shorten an adjustment time greatly by applying the 1st bias voltage to one terminal of a varactor diode and applying the 2nd variable bias voltage to the other terminal, and varying the oscillation frequency. CONSTITUTION:When the oscillation frequency at a specific tuning voltage varies owing to the variance of the varactor diode 8, one of adjusting stubs formed previously is connected to a microstrip line 3 through a gold wire or gold bibbon 15 as a rough adjustment to suppress variances in oscillation frequency at the specific tuning voltage within a certain range. Then, the slider of a variable resistance 14 is adjusted to vary a voltage Va- applied to the anode side of the varactor diode 8. Thus, the voltage is adjusted through this variable resistance 14 to vary the reverse bias voltage applied between the anode and cathode of the varactor diode 8, namely, varying the junction capacity of the varactor diode 8, obtaining the specific oscillation frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a microwave oscillator equipped with a varactor diode as an oscillation component.

(Prior art) Conventionally, this type of microphone [single-wave oscillator] has been used in various radar devices and microwave devices that require electrical tuning. The generated microwave signal is mixed with the local oscillator output and detected in the mixer and converted to an intermediate frequency.
A microwave oscillator is used for this local oscillator.

This microwave oscillator uses a method that allows electrical tuning, and by changing the tuning voltage, the desired intermediate frequency,
For example, I try to use 45 MHz.

Same sl! The frequency variable range of the microwave oscillator using the I voltage is always 45 M l - I Z while responding to changes in the oscillation frequency due to changes in the ambient temperature of the magnetron and microphone wave oscillator used as radar transmitters. The intermediate frequency must be determined within a range of 1.

However, because there are variations in the microwave semiconductor elements incorporated into microwave optical oscillators, the tuning voltage VO1 at an ambient humidity of 100, that is, the oscillation frequency at a predetermined tuning voltage, differs from oscillator to oscillator. Tuning within a variable voltage range (which was more difficult).

The reason for this will be explained in more detail as follows.1. Since Figure 2 shows the oscillation frequency characteristics versus the tuned current 1F of a microwave oscillator, the influence of ambient temperature is ignored for the sake of explanation.

That is, the oscillators A, B, and C have different characteristics A0, 80 . I have Go. For example, oscillator A has a tuning voltage V1. Vo, V2 each have an oscillation frequency f1. f
o, f2 are reduced by 1q.

On the other hand, FIG. 3 shows the relationship between the light frequency and the ambient temperature of the magnetron oscillator, and has a temperature characteristic that changes approximately linearly with the ambient temperature.

Therefore, if we assume that only the magnetron oscillator has temperature dependence as shown in Figure 3, then
1: T'o, T2 (however, TI)-'
The oscillation frequency of T O,・T' 2 > is f ml
, f mo, f m2, and if the intermediate frequency obtained by mixed detection of the magnet 1-0 oscillation frequency and the microphone [1-wave oscillation frequency] is, for example, λ45 M[→2,
As shown in FIG.
The ambient temperature of the optical oscillator is about 1. Even if To and T2 change, l fml-Nl.

I fmo-fo I, l fm2-f 21 can each have a constant middle/interlayer wave number of 45 MHz (17 1゜Next, looking at oscillators B and C with different characteristics, the same oscillator 4 to increase the oscillation frequency to 1; &
, for example, taking oscillator i & generator B as an example, the oscillation frequency [1 is 1
To obtain 516, change the tuning voltage from Vl to ■1', and to obtain the oscillation frequency fo/i-, change the tuning voltage from VO to VO
', and in order to further obtain the oscillation frequency f2, it is sufficient to change the Ii1 adjustment voltage voltage 2 to V2-. That is, the tuning voltage V1-. is shifted higher than the tuning voltage of the oscillator A.
It is sufficient to set Vo' and V2- to 1J°.

This point also applies to oscillator C, which has the same oscillation frequency f1 as oscillator Δ. In order to obtain fo, f2, the tuning voltage V1. VO and V2 are each lower tuning voltage V1''
, ■o″, ■2″.

However, this method of eliminating variations in the characteristics of the oscillators A, B, and 'C by adjusting the voltages of the varactors has the following problem.

First, in FIG. 2, the upper and lower limits of the adjustable varactor W4 voltage are determined.

Figure 4 shows the relationship between the junction capacitance ffJ and the applied voltage of the varactor diode. Since we use the part where the relationship between the applied voltage and the junction eccentricity is approximately a straight line, the lower limit of the varactor tuning voltage is approximately 5V. becomes. On the other hand, the withstand voltage of a varactor diode is usually about 40 to 50V, and the voltage limit is, for example, 30V due to the m source of the oscillator. Therefore, the microphone shown in FIG.
The range of varactor voltage that can be used to compensate for leakage is limited to approximately 5 to 30V.

The result 1. The same W4 voltage close to the l2 limit ■Oscillation frequency @2
When tuning oscillator B to oscillator A that obtains f2, it is necessary to set a tuning voltage V2' higher than tuning voltage ■2, and if this tuning voltage ■2- exceeds the upper limit of 30V, the variation will occur. F! I can't do the 4th order.

On the other hand, when adjusting oscillation = C to the oscillator A which obtains the oscillation frequency f1 with the same vA voltage V1 close to the lower limit, it is necessary to set the tuning voltage V1- below the lower limit of 5V for the tuning voltage L[,
As shown in Figure 4, below 5V, the junction capacitance 1 causes a sudden change in response to a voltage change (1, requiring extremely delicate adjustment of the tuning voltage 1''), making it extremely difficult! It becomes tidy.

The above explanation was based on the case where the tFA degree dependence of the microwave oscillator was ignored, but in reality, as shown in FIG. 5, the ambient temperature T1. For example, at ambient temperature T = T2, the tuning voltage approaches the lower limit of 5V, while at ambient temperature T = T1, the tuning voltage approaches the upper limit of 30V, and varactor tuning Adjusting the variation by adjusting the voltage becomes even more difficult.

The present invention was developed in view of this situation, and will be explained in more detail with reference to a schematic diagram of a conventional microwave oscillator used in radar equipment, etc., which is not shown in FIG. Then, the following is true.

In FIG. 6, 1 is a microwave integrated circuit board (hereinafter r
Dielectric materials such as alumina ceramics, quartz, and Teflon, which have low dielectric loss in the microwave band, are used in the MIC1 plate. 2 is a gallium arsenide field effect transistor (referred to as IX rGaAsFE), the source terminal S of GaAsFET 2 is connected to the microstrip line 4, the drain terminal is connected to the microphone [1] strip line 3, The microstrip lines 5 (, - are connected to each other.

A DC blocking capacitor 6 is connected between the microstrip lines 5 and 7, and a microstrip line 9 is connected between the microstrip lines 5 and 7.
The varactor diode 8 is connected between Reverse bias state C
I am using it.

In addition, the source terminal S of GaAsFET2 has a power supply voltage S
is applied, and a resistor 11 is connected to the drain terminal.

In the microwave oscillator having the above configuration, oscillation is caused by the destabilization of the GaAsFET 2 due to the internal feedback capacitance n4 between the gate and the drain, and the oscillation output is taken out from the drain terminal via the line 3.

However, such a microphone [in a single wave oscillator,
Varactor diode 8 and GaASFET
Since there are variations in characteristics of elements such as 2, the relationship between the tuning voltage and the oscillation frequency differs from oscillator to oscillator. Therefore, an adjustment stub 10 is formed in advance at a location that contributes to the oscillation frequency, for example, near the microstrip lines 3 and 9, and this adjustment stub 10 is selectively connected to the microstrip lines 3 and 9 to incorporate it. In order to compensate for variations in the tuning voltage versus oscillation frequency characteristics due to variations in elements and elements, careful adjustments were made so that the same oscillation frequency could be obtained even if the oscillator was changed.

(Problem to be Solved by the Invention) However, in the conventional method of correcting oscillation frequency variations using adjustment stubs, although it is possible to roughly adjust the frequency by selectively connecting the stubs, it is difficult to adjust the frequency in steps. Since the adjustment was made in a number of steps, it was difficult to make fine adjustments to a predetermined frequency, and even if fine adjustments were made, the adjustment took time and effort.

In addition, varactor diodes have the largest change in junction capacitance in the range of 0 to 5 V with respect to the applied voltage, and therefore the frequency change in the tuning voltage vs. frequency characteristic is also large.

Therefore, a problem arises when it is desired to use a frequency characteristic with relatively good linearity with respect to the tuning voltage. That is,
As the characteristic graph in Figure 4 shows, the tuning voltage is 0=
Up to about 5V, the junction capacitance changes are too steep to be used, and the voltage that can actually be used is 5 to 30V. This means that a power source that is 5V higher than the practical voltage range must be prepared, which is uneconomical.

(Means for Solving the Problems) The present invention has been made in view of the problems of the conventional J.
(Instead of using one terminal by grounding, a voltage adjustment means is used to apply a first bias voltage, for example, a constant tuning voltage, to one terminal of the varactor diode and vary a second bias voltage to the other terminal. This voltage adjusting means adjusts the reverse bias voltage across the varactor diode J3 to change the oscillation frequency.

That is, the tuning voltage vs. oscillation frequency characteristic line BO shown in FIG.
1CO is transferred to AO.

(Example) FIG. 1 is a schematic diagram showing an embodiment of the present invention.

First of all, 1 is a MIC board, and a dielectric material such as alumina ceramics, quartz, zaphire, Teflon, etc., which has low dielectric loss in the 1-wave band is used for the microphone. The microstrip lines 3, 4, 5, 7, 9, etc. that constitute the microwave oscillation circuit are formed by vapor deposition, sputtering, or screen printing, etc., 2 is a Ga As FET and the source terminal S
is connected to the microphone 1 to the strip line 4, the drain terminal is connected to the line 3, and the gate terminal G is connected to the microphone 1 strip line 5. A DC blocking capacitor 6 is connected between the microstrip lines 5 and 7, and a varactor diode 8 is connected between the microphone strip lines 5 and 7. The anode side of the varactor diode 8 is connected to the bias terminal 13 of the MITI board,
The cathode side is connected to the bias terminal 12. Furthermore, Ga
A power supply voltage VS is applied to the source terminal S of the As FET, and a resistor 11 is connected to the drain terminal.

The oscillation is QaΔ due to the internal return capacity Φ between the gate and drain.
This occurs due to instability in the 5FET, and the oscillation output is taken out from the drain terminal via the microstrip line 3.

On the other hand, a tuning voltage Vt is applied from a voltage source (not shown) to a terminal 12 connected to the cathode side of the varactor diode 8, and a voltage adjustment means is applied to the other terminal 13 connected to the anode side of the varactor diode 8. The slider of the variable resistor 14 provided as
A constant voltage va is applied to the bias terminal 13, and a variable voltage Va- is applied to the bias terminal 13 by adjusting the slider. .

Here, the relationship of Vt≧va holds between the voltage Va of the variable resistor 14 and the tuning voltage Vt of the terminal 12, and since Va>Va-, the varactor diode 8 is always reverse biased. It will be used in the state. Also, the voltage Va of the variable resistor 14
Even if Vt is applied as -Va, the effect remains unchanged as long as the relationship of Vt≧-Va', . . . -Va holds true.

In addition, regarding the direction of the varactor diode 8, even if the anode is connected to the microstrip line 9 side and the cathode is connected to the microstrip line 7 side, and the tuning voltage Vt is applied as -Vt to the anode side, in this case, -vt <va
If the relationship ≦'Ja holds true, the effect will not change. Furthermore, even if the voltage Va of the variable resistor 14 is applied as -Va, the effect remains unchanged as long as the relationship -Vt≦-Va<V (1') holds.In other words, the same FAN voltage V
The relationship between t and bias voltage ■a is the varactor diode 8
C is determined so that C is always in a reverse bias state.

In addition, in the embodiment shown in FIG. 1, as a means for coarsely adjusting the oscillation frequency, an adjustment stub 10 is placed at a location that contributes to a change in the oscillation frequency, for example, near the microstrip lines 3 and 9, as in a conventional microwave oscillator. is formed in advance.

Next, to explain the operation of the embodiment shown in FIG. 1, Ga△5FE
If the oscillation frequency at J3 changes to a predetermined tuning voltage due to variations in T2 or varactor diode 8, then, as in conventional microwave oscillators, first adjust the coarse tuning in advance. One of the stubs 10 is connected to the microstrip line 3 or 9 with a gold wire or gold ribbon 15 to suppress variations in oscillation frequency at a predetermined tuning voltage within a certain range. In the embodiment shown in FIG. 1, one of the adjustment stubs 10 is connected to the microstrip line 9 with a gold wire or gold ribbon 15.

In this way, coarse adjustment is first performed by connecting the adjustment stub 10, and then one stylus of the variable resistor 14 is adjusted to vary the voltage Va- applied to the anode side of the varactor diode 8. By adjusting the voltage using the variable resistor 11, it is possible to change the reverse bias voltage applied between the anode and cathode of the varactor diode 8, that is, to change the junction capacitance of the varactor diode 8, to obtain a predetermined oscillation frequency.

According to this method, even if the GaAs FET 12, barac, and diode 8 have a basso = r, the predetermined excavation frequency can be set by adjusting the variable resistor 14. Since this is a fine adjustment, the adjustment is much easier and faster than in the prior art, in which adjustment is performed using only an adjustment stub, and the predetermined oscillation frequency can be reliably increased by 1:7.

Further, as the tuning voltage Vt, for example, 0-25V is prepared, and the l! of the variable resistor 14 is prepared. ! l If the voltage applied to the FJJ element is set to about 15 V and the variation in oscillation frequency due to variation in the element is corrected, it is possible to use only the characteristic f[portion with relatively good linearity within the variable range of the tuning voltage Vt, and It is also possible to correct variations in the oscillation frequency due to variations in oscillation frequency, and for the tuning voltage Vt, it is possible to prepare a voltage as high as 5 cm, like the conventional +5 to +30 cm described above. This eliminates the inconvenience of not being able to do so.

(Effects of the Invention) As described above, in the present invention, in a microwave oscillator equipped with a varactor diode, a first bias voltage is applied to one terminal of the varactor diode, and a second bias voltage is applied to the other terminal of the varactor diode. Since a frequency adjustment means is provided to change the oscillation frequency by applying a variable bias voltage, even if there are variations in the GaAsFET or varactor diode used as the microwave oscillator, the variation in the element can be eliminated by finely adjusting the excavation frequency using the voltage adjustment means. The effects can be removed and the oscillation frequency can be precisely adjusted to a constant value.

Therefore, according to the present invention, the inspection and adjustment time caused by the inconvenience that the oscillation frequency for a predetermined tuning voltage varies from oscillator to oscillator in the local oscillator of a radar device, for example, can be significantly reduced, and a great economic effect can be brought about. .

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a microwave oscillator showing an embodiment of the present invention, and Fig. 2 is a graph showing the tuning voltage versus oscillation frequency characteristics when the oscillation frequency of the microwave oscillator does not change with temperature. , Fig. 3 is a graph showing the Magneto-Ron oscillation frequency characteristics with respect to changes in ambient temperature, Fig. 4 is a graph showing the applied voltage versus junction capacitance characteristics of a varactor diode, and Fig. 5 is a graph showing the characteristics of a microwave oscillator and a varactor diode. 7 A graph showing the relationship between the tuning voltage and the oscillation frequency of the magnetron when the excavation frequency changes with the ambient temperature. Figure 6 shows a conventional example. It is a schematic block diagram. 1: Microwave integrated circuit board (M [C board)] 2: Gallium arsenide field effect transistor (GaAs FET) 3.4, 5, 7, 9: Microphone [1 strip line 6: DC blocking capacitor 8: Varactor diode 10: W4 adjustment stub 11: Resistor 12, 13: Bias terminal 14: Variable resistor 15: Gold wire or gold ribbon

Claims (1)

[Claims] In a microwave oscillator equipped with means for changing the oscillation frequency by varying the junction capacitance of a varactor diode, a first bias voltage is applied to one terminal of the varactor diode, and a first bias voltage is applied to the other end of the varactor diode. A microwave oscillator characterized in that it is provided with voltage adjustment means that changes the oscillation frequency by varying the second bias voltage.