JPH0213483B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a microwave solid-state oscillator for microwave integrated circuits, and particularly to a microwave solid-state oscillator that is easy to configure and adjust, has a wide oscillation frequency range, and has high oscillation frequency stability. This is what I did.

As a semiconductor direct oscillation device in the microwave band,
Impact diodes and Gunn diodes are mainly used, but since these are semiconductor devices, they have large variations in characteristics and temperature dependence, and when configuring an oscillator with a microstrip line, the resonator is Since the load Q is low, the temperature dependence of the oscillation frequency is also large, and some countermeasures must be taken for applications that require a high degree of frequency stability. One way to solve this problem is to use a dielectric resonator that has good temperature stability and a high no-load Q.

FIG. 1 shows an example of a conventional microstrip type single-resonance stabilized oscillator using a Gunn diode. In addition, a in FIG. 1 is a top view, and b is its A-A.
FIG. To explain this, a Gunn diode 3 is mounted on a microstrip pattern 2 formed on a dielectric substrate 1 at a position as shown in the figure, and a disk-shaped diode is mounted at an electrical angle of 0 from the Gunn diode 3. Alternatively, a cylindrical dielectric resonator 4 is provided, oscillation is made at the resonant frequency of the dielectric resonator 4, and an output is taken out from the output end 5. DC bias is supplied through a low pass filter 6. Further, a non-reflection terminating resistor 8 is connected to the terminal opposite to the output terminal 5 via a DC block 7 for blocking direct current bias. Further, reference numeral 9 in the figure is a metal support that serves as a ground conductor for the microstrip line and a heat sink for the Gunn diode 3. In this configuration, the load conductance is optimized only near the resonant frequency of the dielectric resonator, and at frequencies far from the resonant frequency, the load conductance becomes large and oscillation stops. Therefore, with this configuration, in principle, single mode oscillation occurs without mode jump, and the stability of the oscillation frequency is mostly determined by the stability of the resonant frequency of the dielectric resonator 4, and high Q makes it highly stable. A highly stable oscillator can be realized by using a dielectric resonator of 100%.

However, in the conventional example described above, the maximum value of the oscillation output is determined by the characteristic impedance of the microstrip line in the diode mount. Must be determined taking impedance into consideration. However, it is difficult to measure the load impedance seen from the diode when the diode is mounted, and in the end, creating a microstrip pattern that optimizes the output must be done through trial and error. Furthermore, when using diodes with different output levels, it is necessary to recreate this pattern. Furthermore, since the DC block 7 and the non-reflection terminating resistor 8 are required, the configuration becomes complicated. By the way, in order to change the oscillation frequency in the above oscillator, the resonant frequency of the dielectric resonator 4 can be changed by moving the metal screw 10 provided on the top of the dielectric resonator 4 closer to or away from the dielectric resonator 4. However, the variable range of the resonant frequency of the dielectric resonator is several hundred MHz, so in the above configuration, the oscillation frequency range is at most several hundred MHz. Therefore, such an oscillator cannot be used as a broadband signal generator.

The present invention is designed to eliminate such drawbacks of the conventional example, and embodiments thereof will be described below with reference to the drawings. Figure 2 a is its top view, b
is a sectional view taken along the line B-B. In those drawings, a semiconductor direct oscillation device 12 is a dielectric substrate 10
It is connected to a microstrip line 11 at one end, and a DC bias is supplied from a terminal 20 through a low-pass filter 13. A first TE (Transverse Electric) mode dielectric resonator 14 having a resonant frequency ₁ is located at a distance from the semiconductor direct oscillation element ₁₂ such that the electrical angle is approximately π/2 at the first center frequency 1 on the dielectric substrate 10. It is placed above the microstrip line 11 so as to be magnetically coupled to the microstrip line 11, and is located at a distance from the semiconductor direct oscillation element 12 such that the electrical angle is approximately π/2 at the second center frequency ₂ , and the first On the dielectric substrate 10 on the opposite side to the TE mode dielectric resonator 14 and the microstrip line 11, a second TE mode dielectric resonator 15 having _two resonant frequencies is connected to the microstrip line. It is placed so as to be magnetically coupled with 11. The output is taken out from the terminal 16, and in order to change the resonance frequency of the first and second TE mode dielectric resonators 14 and 15, the output is taken out in the vertical direction, that is, the first and second TE mode dielectric resonators 14 and 15. Metal plates 17 and 18 are provided so as to be able to approach and separate from the metal plates 14 and 15, respectively. Note that 19 in the figure is a metal support that serves as a ground conductor and a heat sink for the semiconductor direct oscillation element 12.

Next, the operation of this embodiment will be explained. In addition,
Two TE mode dielectric resonators 14, 1 in Fig. 2
5 have similar functions, so let's start with the first one.
The operation when there is only the second TE mode dielectric resonator 14 will be explained, and then the effect of adding the second TE mode dielectric resonator 15 will be explained. When the coupling part of the first TE mode dielectric resonator 14 and the microstrip line 11 is taken as the reference plane T ₁ , the real part of the load impedance when looking at the load side from this T ₁ is the real part of the load impedance of the dielectric resonator 14 Since the equivalent conductance is inserted in series with the characteristic impedance Z _p (usually chosen to be 50 Ω) of the microstrip line 11, it becomes larger than Z _p , and the imaginary part of the load impedance becomes almost zero at resonance. .
Furthermore, by changing the distance between the first TE mode dielectric resonator 14 and the microstrip line 11, the degree of coupling changes, and the size of the equivalent conductance inserted in series with Z _p can also be changed. .
Furthermore, the real part of the impedance seen from the position of the semiconductor direct oscillation element 12 (reference plane T ₂ ) which is π/2 electrical angle away from the reference plane T ₁ can be made smaller than Z _p at the time of resonance. That is, the load circuit viewed from the reference plane _T2 can be operated as a single series resonant circuit with variable resistance.

Normally, a Gunn diode or an impact diode oscillates with a low impedance load, so by adjusting the position of the first TE mode dielectric resonator 14 as described above, the load as seen from the semiconductor direct oscillation element 12 can be adjusted. Oscillation output can be maximized by reducing the real part of impedance.

Next, the effects of the second TE mode dielectric resonator 15 will be explained. It is clear from the previous explanation that if the distance between the dielectric resonator 15 and the semiconductor direct oscillation element ₁₂ is set to approximately π/2 in electrical angle at the resonance frequency 2 of the second TE mode dielectric resonator 15, It oscillates at ₂ like this. The difference between the resonance frequencies ₁ and ₂ of the first TE mode dielectric resonator 14 is selected to be several hundred MHz ( ₁ < ₂ ), so that it oscillates at ₁ in the low frequency band and at ₂ in the high frequency band. For example, since ₁ and ₂ each have a variable range of about several hundred MHz, an oscillator using such two dielectric resonators can achieve an oscillation frequency range of 1 GHz or more. In order to prevent oscillation at ₂ from occurring when oscillation at ₁ occurs, the metal plate ₁₈ is brought into close contact with the second TE mode dielectric resonator 15 to lower the no-load Q. It is sufficient to prevent resonance from occurring. On the other hand, in order to obtain only the oscillation at ₂ , the metal plate 17 may be brought into close contact with the first TE mode dielectric resonator 14 to prevent the resonance at ₁ from occurring.

As described above, the present invention makes it possible to adjust the load impedance seen from the semiconductor direct oscillation element by adjusting the position of the dielectric resonator, so that the oscillation output can be easily maximized. Furthermore, since two dielectric resonators with different resonant frequencies are used and are selectively used depending on the frequency band, it has an extremely excellent feature of being able to obtain a wide oscillation frequency range.

[Brief explanation of drawings]

Figures 1a and b are a top view and a cross-sectional view taken along the line A-A of a conventional single-resonator type microwave solid-state oscillator, and Figures 2a and b are a top view and a cross-sectional view taken along the line B-B of an embodiment of the present invention. FIG. 10... Dielectric substrate, 11... Microstrip line, 12... Semiconductor direct oscillation element, 13...
...Low pass filter, 14, 15... TE mode dielectric resonator, 16... Output end, 17, 18...
Metal plate, 19...metal support stand.

Claims (1)

[Claims] 1. A semiconductor direct oscillation element is electrically connected to one end of a microstrip line constructed on a dielectric substrate, and an electric angle of approximately π is set from the semiconductor direct oscillation element to the microstrip line with respect to the resonant frequency. Two dielectric resonators having different resonance frequencies and having metal plates that serve both frequency adjustment and resonance suppression are installed on dielectric substrates located /2 apart and close to the microstrip line. The structure is such that the microstrip line is fixed so as to sandwich it and operated as a reflection type resonator, and the dielectric resonator having the lower resonant frequency of the two dielectric resonators has a lower resonant frequency. 1. A microwave solid-state oscillator, characterized in that the oscillation frequency of one side is determined, and the higher oscillation frequency is determined by a dielectric resonator having a higher resonance frequency.