JPS60224310A - Microwave semiconductor oscillator - Google Patents

Abstract

PURPOSE:To obtain an approximately certain oscillated frequency without the influence of the ambient temperature by providing a bias circuit, which gives a reverse bias voltage to a varactor diode, with a resistor having a positive coefficient of temperature. CONSTITUTION:A bias circuit 6 divides a DC voltage Vt by resistances Ra and Rc and a resistance Rb, which has a positive coefficient of temperature and is dependent upon temperature, to generate a reverse bias foltage Vc to a varactor diode 4. Resistance values or resistances Ra and Rc are so set that the reverse bias voltage Vc is V1, V0, and V2 for the ambient temperature T1, T0, and T2 respectively. Thus, an approximately certain oscillated frequency f0 is obtained without the influence of the ambient temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a microwave semiconductor oscillator used in the microwave band.

(Prior Art) Conventionally, semiconductor direct oscillation elements used in this type of microwave semiconductor oscillator include gallium arsenide field effect transistors (hereinafter referred to as GaAsFETs), microwave junction transistors, Gunn diodes, invat diodes, etc. Although these oscillation elements are mainly used, since they are semiconductor elements, they have large variations in characteristics and large temperature dependence.

In addition, in an oscillation circuit using the above-mentioned oscillation element, a varactor diode is inserted in the middle of the microstrip line forming the oscillation circuit, and the junction capacitance of the varactor diode is electrically changed by a reverse bias voltage to adjust the resonant frequency of the line. However, in such an oscillator whose oscillation frequency can be varied, the no-load Q of the resonator is low, so the humidity dependence of the oscillation frequency is also large.

As a method of controlling the temperature characteristics of the oscillation frequency in such a temperature-dependent oscillator, a thermistor is installed in the bias circuit that applies a reverse bias voltage to the varactor diode, and the reverse voltage applied to the varactor diode is adjusted according to the temperature characteristics of the thermistor. By changing the bias voltage depending on the temperature,
As a result, it is possible to make the oscillation frequency have a predetermined temperature dependence.

However, in the method of controlling the temperature characteristics of the oscillation frequency in an oscillator using a thermistor, the characteristics of the resistance change (negative slope) with respect to temperature change of the thermistor are almost equal over the operating temperature range, for example, -20°C to 60°C. Because of the relationship in a ratio series, when the oscillation frequency changes in a geometric progression with changes in humidity, or by connecting a fixed resistor in parallel with the thermistor, it is possible to Since the relationship is almost linear, it is effective only when the oscillation frequency changes almost linearly with respect to temperature changes. However, there are few oscillators with such characteristics. For example, when a Gunn diode is used as a semiconductor direct oscillation element, the temperature characteristics of the oscillation frequency are not linear due to the temperature characteristics of the Gunn diode itself, and the oscillation frequency decreases as the temperature increases. The decreasing slope becomes larger.

Therefore, in an oscillator that uses a Gunn diode as a semiconductor oscillation element, a resistor, such as a thermistor, whose resistance changes almost geometrically with respect to temperature changes within the operating temperature range is used to control the oscillator to obtain a predetermined temperature characteristic. Even if you try,
It has not been possible to construct an oscillator in which the relationship between oscillation frequency and temperature change is approximately linear.

On the other hand, when high frequency stability is required, a method is generally used that uses a dielectric resonator with good temperature stability and high non-negative giQ. It is complicated to determine the optimum operating conditions, such as factors governing the Since the stability is affected by the difference in temperature, it is extremely difficult to keep frequency fluctuations small over a wide temperature range, and furthermore, it has become economically expensive to use a dielectric resonator.

In other words, the method using a dielectric resonator is an effective method when high frequency stability is required, that is, when the oscillation frequency changes almost linearly with temperature change without temperature dependence, but on the other hand, it is an effective method when high frequency stability is required. It was not suitable for situations such as when it was desired to set the temperature characteristics of

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems.Even in an oscillator having a temperature characteristic of non-linear frequency change with respect to temperature, the temperature dependence of the varactor diode is It is an object of the present invention to provide a microwave semiconductor oscillator in which the relationship between oscillation frequency and temperature change can be set almost linearly by applying a bias voltage.

(Structure of the Invention) In order to achieve this object, the second invention provides a line that provides an oscillation frequency by a capacitance corresponding to a reverse bias voltage in the middle of a microstrip line that forms an oscillation circuit using a semiconductor direct oscillation element in the microphone D-wave band. In a microwave semiconductor oscillator equipped with a varactor diode that sets the resonant frequency of A bias circuit for generating a reverse bias voltage to be applied to the varactor diode to be set is provided.

(Embodiment) FIG. 1 is a schematic diagram showing an embodiment of the present invention using a can diode as a semiconductor direct oscillation element.

First, to explain the configuration, 1 is a microwave integrated circuit board (
It is a microstrip line constructed by vapor deposition, sputtering, screen printing, etc. on a dielectric substrate such as alumina ceramics, quartz, sapphire, or Teflon, which has low dielectric loss in the microwave band. A circuit pattern of a microwave semiconductor starting circuit is formed, and a Gunn diode 3 as a semiconductor direct oscillation element is installed, a varactor diode 4 is inserted in the middle of the microstrip line 2, and the junction capacitance of the varactor diode 4 is reversed. By electrically changing the bias voltage, the resonant frequency of the line can be changed.
The structure is such that the oscillation frequency can be varied according to this resonance frequency.

Here, the temperature characteristic of the oscillation frequency in the oscillator using the Gunn diode 3 is not linear due to the temperature characteristic of the Gunn diode 3 itself, and has a temperature dependence f1 in which the slope of decrease in the oscillation frequency increases as the temperature increases.

Regarding the oscillator using such Gunn diode 3,
Bias circuit 6
is provided.

The bias circuit 6 forms a voltage divider circuit for the DC voltage Vt with resistors Ra and Rc, further connects a temperature-dependent resistor Rb with a positive humidity coefficient in parallel with the resistor Rc, and connects the resistor Ra and the resistor RC in parallel.
A divided voltage between the temperature-dependent resistor Rb and the parallel resistance of the temperature-dependent resistor Rb is generated as a reverse bias voltage Vc for the varactor diode 4.

Here, as the temperature-dependent resistor Rb, for example, Posistor (trademark) is used, and the resistance temperature dependence of Posistor is within the operating temperature range, for example, from -20°C to +60°C.
In addition to those that are approximately equal in density at °C, there are various types that have an increasing rate of change as the temperature increases.

Next, setting of the temperature characteristics of the oscillation frequency by the temperature dependent resistor Rb provided in the bias circuit 6 will be explained in detail.

FIG. 2 is a graph showing the temperature characteristics of the oscillation frequency when temperature control is not performed. That is, the ambient temperature T is
=T1. If you change the reverse bias voltage VC to the varactor diode 4 while keeping it constant so that T0 or T2 (T1<To<T2), each ambient temperature T1
．． Different oscillation frequency characteristics can be obtained for each To and T2.

Therefore, in order to always obtain a substantially constant oscillation frequency fo despite changes in the ambient temperature T, it is necessary to set the ambient temperature T=T1 and the reverse bias voltage VC=V1. If the ambient concentration T=To, the reverse bias voltage VC=VO, and the ambient temperature -T2, the reverse bias voltage VC-V2 should be 1-, and such adjustment of the reverse bias voltage VC for the ambient temperature 1!31- Therefore, it is possible to always obtain a substantially constant oscillation frequency fO without being affected by ambient humidity.

That is, the oscillation frequency f=fo given in the graph of FIG.
The relationship between the reverse bias voltage VC and the ambient temperature T to maintain the temperature is as shown in the graph of FIG. 3.

Therefore, in the bias circuit shown in FIG. 1, the resistance Ra is adjusted so that a resistance value based on the humidity-dependent resistance Rb that generates the reverse bias voltage Vc given in the graph of FIG. .

What is necessary is to determine the value of RC.

Of course, as is clear from the graph in FIG. 3, the slope of the reverse bias voltage VC increases with the increase in ambient temperature. A POSISTOR is used that has a positive temperature coefficient and a resistance temperature characteristic in which the change ratio at high temperature is larger than the change ratio at low temperature and normal humidity.

Briefly, the reverse bias voltage Vc, which is the output voltage of the temperature control circuit 6, is expressed by the following equation.

Vc = Vt ・(Rb Rc / (Rb + Rc
) ) / (Ra −+−Rb Rc / (Rb
+Rc ) )...(1) Here, the temperature-dependent resistance Rb has a positive temperature coefficient, and the resistance temperature characteristics are low humidity and the change ratio at high temperature is larger than the change ratio at room temperature. Select a POSISTOR with an ambient temperature of T1. The values of the temperature-dependent resistance Rb at To and T2 are R1 and Ro, respectively.

R2, reverse bias voltage Vc = V1, Vo,
Resistance values Ra and R can be calculated by solving two-dimensional simultaneous equations with resistances Ra and RC as unknowns when given as V2.
c can be determined.

Next, to explain the operation of the embodiment shown in FIG.
a and Rc, a reverse bias voltage VC given by the above equation (1) is created and applied to the varactor diode 4, and this reverse bias voltage Vc changes depending on the ambient temperature as shown in the graph of FIG. The reverse bias voltage Vc given by the temperature characteristics shown in FIG. 3 is as shown in FIG. 2.
This means that a nearly constant oscillation frequency f = fo is always given, and the temperature-dependent reverse bias voltage Vc for the varactor diode 4 can be varied to compensate for fluctuations in the oscillation frequency of the oscillator using the Gunn diode 3 due to the ambient temperature. , the junction capacitance of the varactor diode 4 is adjusted to keep the resonant frequency of the line at a constant oscillation frequency f=fo, so that the oscillation frequency fo is always almost constant regardless of fluctuations in ambient temperature.
A microphone D-wave semiconductor oscillator with less temperature dependence can be obtained.

As an actual measurement example using the embodiment shown in FIG.
iT1=-20'C, To=+20℃, T2=+60
℃, the fluctuation width of the oscillation frequency was about IMHz when the oscillation frequency fo=9455MH7.

In the embodiment shown in FIG. 1, temperature control is performed so that the oscillation frequency remains approximately constant with respect to changes in ambient temperature, but it is also possible to give the oscillation frequency a predetermined temperature characteristic.

For example, the slope of the oscillation frequency with respect to temperature in the 9GH7 band of a magnetron used as a radar transmitter is approximately -
The value is approximately 0.2/MH2/'C. Therefore, in order to have a temperature characteristic that has a slope with respect to temperature that is almost the same as the slope of the oscillation frequency with respect to temperature of the magnetron oscillator,
If the oscillator shown in Fig. 1 is configured and used as a local oscillator, it is possible to create fluctuations in the oscillation frequency of the local oscillator on the receiving side by following temperature fluctuations in the oscillation frequency in the magnetron on the transmitting side. Frequency fluctuations depending on the humidity of the magnetron in the intermediate frequency signal obtained by mixing with the oscillation frequency from the oscillator can be removed.

FIG. 4 is a schematic diagram showing another embodiment of the present invention using a QaAs-FET as the semiconductor direct oscillation device.

In FIG. 4, a circuit pattern of a microstrip line 2 constituting an oscillation circuit is formed on the MIG board, and a GaAs-FET 7 as a semiconductor direct oscillation element and a DC blocking capacitor 8 are provided, and the oscillation circuit is also formed. A varactor diode 9 is provided in the middle of the microstrip line 2, and in order to control the reverse bias voltage of the varactor diode 9, a bias circuit 6 including a temperature-dependent resistor Rb is provided.

The slope of the oscillator using the Ga As FET7 shown in Fig. 4 with respect to temperature in the 9 GHz band is approximately -1°0 MHz.
/°C, and has temperature dependence in which the oscillation frequency changes almost linearly with temperature.

Therefore, as in the case of the oscillator using the Gunn diode shown in FIG. 1, if a POSISTOR with appropriate temperature characteristics is selected as the temperature-dependent resistor Rb in the embodiment shown in FIG. Similarly, it is possible to obtain an oscillation circuit with little temperature dependence that can always obtain an oscillation frequency that is almost constant with respect to the ambient temperature, or an oscillator that has temperature characteristics that almost match the temperature characteristics of the oscillation frequency of a magnetron oscillator used in radar transmitters, etc. be able to.

Further, the present invention provides the above Gunn diode and GaAS F
The present invention is not limited to a microwave semiconductor oscillator using an ET as a semiconductor direct oscillation element, but can also be applied to other microwave semiconductor oscillators using a microwave junction transistor, an invat diode, etc. as a semiconductor direct oscillation element.

(Effects of the Invention) As explained above, according to the present invention, an oscillation frequency is provided by a semiconductor direct oscillation element in the microwave band through a capacitance corresponding to a reverse bias voltage in the middle of a microstrip line forming an oscillation circuit. In a microwave semiconductor oscillator equipped with a varactor diode that sets the resonant frequency of the line, a resistor has a positive temperature coefficient with respect to changes in ambient temperature, and a predetermined humidity characteristic is set at the oscillation frequency based on the humidity coefficient of this resistor. Since a bias circuit is provided that generates a reverse bias voltage for the varactor diode that sets setting to reduce the temperature dependence of the oscillation frequency in the oscillator circuit so that the oscillation frequency is always constant relative to the ambient temperature, or to reduce the oscillation frequency of the oscillator itself for matching with other circuit elements. It is possible to provide an appropriate temperature dependence different from the temperature characteristic of the frequency, and the means for providing this temperature dependence can be easily realized by using a humidity dependent resistor with a positive temperature coefficient, and dielectric resonance The device configuration is extremely simple compared to the case where a container is used, and it can be realized at a lower cost.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention using a Gunn diode, and Fig. 2 shows the reverse bias voltage using the ambient temperature as a parameter when temperature control is not performed in the embodiment of Fig. 1. A graph showing the relationship between the oscillation frequency, Figure 3 is a graph showing the relationship between the ambient temperature and reverse bias voltage when the oscillation frequency obtained from Figure 2 is kept almost constant, and Figure 4 is a graph showing the relationship between the Ga FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention using an As FET. 1: Microwave integrated circuit board (MIC board) 2: Microstrip line 3: Gunn diode 4.9: Varactor diode 5.8: DC element capacitor 7: Ga As FET Ra, RC: Resistor Rb: 1ff 1 degree dependence Resistor (Posistor) RO Nidrain Resistance Patent Applicant Tokyo Keiki Co., Ltd. Agent Patent Attorney Susumu Takeuchi Figure 2 Figure 3 f + August 20, 1982 Patent Application No. 81562 2 Name of the invention Microwave semiconductor oscillator 3 Relationship with the two amendments Patent applicant I 1 Tokyo person [16 Minami Kamata 2-16, Ward 1] No. 46 Name (338) Tokyo Keiki Co., Ltd. 4, Agent I 1 Column 6 of Detailed Description of the Invention 1, 4th Floor, Nishi-Shimbashi Chuo Hill, 3-15-8 Nishi-Shinbashi, Minato-ku, Tokyo , Details of correction (1) "Resistance change" on page 3, line 11 of the specification is corrected to "resistance change 1."(2> Line 7 of page 11, “Correct temporality j to “characteristic”. (3) Lines 12 to 13, page 14 of the same page [9 of the oscillator
The GHz band j is corrected [when the bias circuit 6 in the oscillator is not provided].

Claims (1)

[Claims] In a microwave semiconductor oscillator, a microwave semiconductor oscillator is equipped with a varactor diode in the middle of a microstrip line that forms an oscillation circuit using a semiconductor direct oscillation element in the microwave band, and sets a resonant frequency of the line that provides an oscillation frequency by a capacitance corresponding to a reverse bias voltage. A resistor having a positive temperature coefficient with respect to changes in ambient temperature is provided, and a bias circuit that generates a reverse bias voltage for the varactor diode that sets the oscillation frequency to a predetermined 11 characteristics based on the concentration coefficient of the resistor. A microwave semiconductor oscillator characterized by: