JPH104315A - High frequency oscillation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the scale of a high frequency oscillation circuit by securing oscillation at two or more frequency bands by means of a single oscillation transistor. SOLUTION: When the high oscillation frequency band switching control voltage is applied to an oscillation frequency band switching control element 42, a switching diode 26 of a resonance circuit block 4 is turned on and switched to the lower resonance frequency to secure an inductive impedance at a low frequency band. The feedback circuit blocks 1, 2 and 3 have their impedances which are controlled so as to satisfy the oscillation conditions at a low frequency band. Thus the blocks 1 to 3 oscillate to satisfy their oscillation conditions at a low oscillation frequency band. When the control voltage of a low level is applied to the element 42, the diode 26 of the block 4 is turned off. Then the block 4 is switched to the higher resonance frequency to secure an inductive impedance at a high frequency band. The blocks 1 to 3 also have the controlled impedances so as to satisfy their oscillation conditions even at a high frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used in a mobile communication system such as an automobile telephone or a portable telephone or a satellite communication device, and is a small voltage controlled oscillator (VCO) oscillating in two or more different oscillation frequency bands. ).

[0002]

2. Description of the Related Art A conventional high-frequency oscillation circuit capable of oscillating in two different frequency bands will be described below. FIG.
FIG. 2 is a configuration diagram showing a conventional high-frequency oscillation circuit capable of oscillating in two different frequency bands. Circuit blocks 80, 8
Reference numeral 1 denotes independent high-frequency oscillation circuits (1) and (2) each including an oscillation transistor. Each output is connected to the coupling circuit block 82, and the high-frequency oscillation circuit (1) 8
One of the signals 0 and (2) 81 is selected and output from the output terminal 83. As described above, in order to configure a high-frequency oscillation circuit capable of oscillating in two or more different frequency bands, the conventional method requires oscillation transistors in the number of oscillation frequency bands.

[0003]

However, in the above configuration, since two or more oscillation transistors are required, there is a problem that the mounting area becomes large including the circuits and the like associated therewith. For downsizing, it is necessary to realize a high-frequency oscillation circuit that oscillates in two or more frequency bands with one oscillation transistor.

The present invention has been made in consideration of such a problem of a conventional high-frequency oscillation circuit, and enables a single oscillation transistor to oscillate in two or more different frequency bands, thereby reducing the circuit size. It is intended to provide a circuit.

[0005]

According to the first aspect of the present invention, there is provided:
This is a high-frequency oscillation circuit including one oscillation transistor, a feedback circuit having two or more different impedances for the transistors, and a resonance circuit connected to the transistor and capable of selecting two or more different resonance frequencies.

According to a third aspect of the present invention, there is provided a single oscillation transistor, a feedback circuit for the transistor capable of selecting two or more different impedances, and a resonance circuit connected to the transistor and having two or more different resonance frequencies. And a high-frequency oscillation circuit comprising:

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing an embodiment. (Embodiment 1) FIG. 1 is a circuit diagram of a high-frequency oscillation circuit according to a first embodiment of the present invention. In FIG.
The resonance circuit block 4 functions as an inductive impedance circuit, and has a high Q value as a resonance circuit. A terminal 43 for applying the tuning voltage is connected to the cathode side of the varactor 24 and the capacitor 23 by the inductor 20 having a sufficient inductor value. Varactor 2
The anode side of 4 is grounded. The strip line resonator 22 connected to the other end of the capacitor 23 has a necessary inductance component in a desired frequency band, and is formed on a dielectric substrate. The other end of the strip line resonator 22 has a switching diode 2 via a capacitor 25 of about 100 pF for a high frequency of about 1 GHz, for example, so as to have a sufficiently low impedance in a desired frequency band.
6 is connected to the anode side. The cathode side of the switching diode 26 is grounded. Further, one end of the inductor 21 having a sufficient inductor value is connected to the oscillation frequency band switching control terminal 42, and the other end is connected to the anode of the switching diode 26 via the bias resistor 27 of the switching diode 26.

Further, an inductor 33 having a sufficient inductor value is connected between a power supply terminal 40 to which a DC supply voltage is applied and the collector of the oscillation transistor 10. The resistor 36 is connected between the emitter of the transistor 10 and the ground. The resistor 34 and the resistor 35 are connected in series between the collector of the transistor 10 and the ground.
The connection points 4 and 35 are connected to the base of the transistor 10. Also, a capacitor 30 connected between the collector of the transistor 10 and the resonance circuit block 4 couples the resonance circuit block 4 and the transistor 10 in high frequency, and one of the capacitors 32 connects to the base of the transistor 10. By grounding the end, the transistor 10 is operated as a common base type high frequency oscillation circuit. Further, an output is obtained from an output terminal 41 via an output coupling capacitor 31 connected to the emitter of the transistor 10.

The feedback circuit block 1 is connected between the collector and the emitter of the transistor 10 and has a capacitor 1
It is configured by a circuit in which the capacitor 11 is connected in series to a parallel circuit of the inductor 2 and the inductor 13, and a desired capacitive impedance can be obtained in two desired frequency bands. Feedback circuit blocks 2 and 3 having a similar circuit configuration also include transistors 10
Are connected between the emitter and the ground, and between the collector and the base, so that the respective capacitive impedances can obtain optimum impedance values in two desired frequency bands. Further, high-frequency noise blocking capacitors 37 are connected between the terminals 40, 42, and 43 and the ground, respectively.

The operation of the high-frequency oscillation circuit according to the first embodiment configured as described above will be described with reference to the drawings.

Now, the oscillation frequency band switching control terminal 4
When the oscillation frequency band switching control voltage applied to the switching circuit 2 is high, the switching diode 2
6 turns on and switches to the lower resonance frequency, and becomes inductive impedance in a low frequency band. Since the feedback circuit blocks 1, 2, and 3 have impedances adjusted to satisfy the oscillation conditions in the low frequency band,
It satisfies the oscillation conditions at low oscillation frequency and oscillates. Also,
When the control voltage of the terminal 42 is low, the switching diode 26 of the resonance circuit block 4 is turned off, and the resonance circuit block 4 switches to a higher resonance frequency, and becomes inductive impedance in a high frequency band. The feedback circuit blocks 1, 2, and 3 also have an impedance adjusted to satisfy the oscillation condition even in a desired high frequency band.
Oscillation is possible in a desired high frequency band.

As described above, according to the present embodiment, oscillation in two different frequency bands can be realized with one oscillation transistor.

In the first embodiment, the feedback circuit blocks 1, 2, and 3 are constituted by impedance elements having two different impedances. However, the feedback circuit blocks 1, 2, and 3 are replaced by the feedback circuit blocks 1, 2, and 3. As shown in FIG. 3, the same effect can be obtained even if two of the capacitors 100 and 101 are configured by a circuit switched by the semiconductor switch circuit 102.

As shown in FIG. 4, the resonance circuit block 4 is composed of two resonators 103, 10 having different resonance frequencies.
4 is switched by a semiconductor switch circuit 105. Alternatively, as shown in FIG.
6, a semiconductor switch element 108 is connected via a DC current blocking capacitor 107 to an intermediate point, and a bias resistor 109 is connected to the semiconductor switch element 108, or as shown in FIG. The same applies to the case where a capacitor 111 is connected to the other end of a resonator 110 having one end grounded, a semiconductor switch element 112 is connected to the capacitor 111, and a bias resistor 113 is connected to the semiconductor switch element 112. The effect can be obtained. (Embodiment 2) FIG. 2 is a circuit diagram of a high-frequency oscillation circuit according to a second embodiment of the present invention. In FIG. 2, a strip line resonator 75 and a capacitor 73 are connected to a strip line resonator 76 having one end grounded. A capacitor 72 is connected to the other end of the stripline resonator 75, and the other ends of the capacitors 72 and 73 are connected to the cathode of the varactor 74 and the inductor 71 having a sufficient inductor value. The anode of varactor 74 is grounded. The other end of the inductor 71 is connected to a terminal 43 for applying a tuning voltage. The two-band resonance circuit block 6 is configured by the above circuits.

The capacitor 30 is connected between the connection point between the strip line resonators 75 and 76 and the collector of the oscillation transistor 10. An inductor 33 having a sufficient inductor value is connected between a power supply terminal 40 to which a DC supply voltage is applied and a collector of the oscillation transistor 10. The resistor 36 is connected between the emitter of the transistor 10 and the ground. The resistor 34 and the resistor 35 are connected to the transistor 10
Connected in series between the collector of the
Is connected to the base of the transistor 10. One end of the capacitor 32 is connected to the base of the transistor 10, and the other end is grounded, so that the transistor 10 operates as a grounded-base high-frequency oscillation circuit. Further, the output is obtained from terminal 41 via capacitor 31 connected to the emitter of transistor 10.

The feedback circuit block 7 is connected between the collector and the emitter of the transistor 10, and is constituted by a circuit in which a capacitor 60 is connected in series with a parallel circuit of a capacitor 62 and a strip line 61 formed on a dielectric substrate. The adjustment provides the desired capacitive impedance in the two desired frequency bands. The capacitor 63 is connected between the collector and the base of the oscillation transistor 10. The feedback circuit block 5 is connected between the emitter of the transistor 10 and the ground, and the capacitors 50 and 51 are connected to the transistor 1.
0 emitter. The other end of the capacitor 50 is grounded, and the other end of the capacitor 51 is connected to the anode of the switching diode 52. The anode of the switching diode 52 is connected to the oscillation frequency band switching control terminal 42 via the bias resistor 53, and the cathode of the switching diode 52 is grounded. Terminal 4
High frequency noise blocking capacitors 37 are connected between 0, 42, and 43 and the ground, respectively.

The operation of the high-frequency oscillation circuit according to the second embodiment configured as described above will be described with reference to the drawings.

The two-band resonance circuit block 6 does not have a changeover switch such as a semiconductor switch element, but has a resonance frequency higher than two desired oscillation frequency bands at the same time.
It functions as a desired inductive impedance circuit in two frequency bands. Further, the resonance circuit block 6 has as high a Q as possible as a resonance circuit at the two resonance points.
Have a value. When the switching diode 52 is turned on and off by the control voltage applied to the terminal 42, the capacitive impedance between the emitter and the ground of the transistor 10 can be switched. Feedback circuit block 7
Can freely adjust the impedance in two frequency bands. As described above, since the oscillation condition can be satisfied in any of the two desired frequency bands, oscillation in the two desired frequency bands can be realized. Switching of the oscillation frequency is performed by the switching diode 5.
2 can be turned on and off.

As described above, according to the present embodiment, oscillation in two different frequency bands can be realized with one oscillation transistor.

The coupling capacitor 30 may be connected between the connection point between the strip line resonator 75 and the capacitor 72 or the connection point between the capacitor 72 and the anode of the varactor 74 and the collector of the oscillation transistor 10. The effect of is obtained.

[0021] In the above-described embodiment, the description has been made on the assumption that the number of desired frequency bands is two. However, the number of desired frequency bands may be three or more.

As described above, one oscillation transistor, a resonance circuit having resonance frequencies in two or more different desired frequency bands, a collector-base, a base-emitter, and an emitter-collector of the oscillation transistor And a feedback circuit having a desired impedance in each of two or more frequency bands, and a configuration in which at least one of the resonance circuit and the feedback circuit can be switched in impedance by a control voltage. The oscillation condition can be satisfied in any of the above frequency bands, and oscillation in two or more desired frequency bands can be realized with one oscillation transistor.

[0023]

As is apparent from the above description, the present invention has an advantage that one oscillation transistor can oscillate in two or more different frequency bands and the circuit scale can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-frequency oscillation circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a high-frequency oscillation circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram illustrating an example of a feedback circuit according to the embodiment of the present invention.

FIG. 4 is a circuit diagram illustrating an example of a resonance frequency switching circuit according to the embodiment of the present invention.

FIG. 5 is a circuit diagram showing another example of the resonance frequency switching circuit according to the embodiment of the present invention.

FIG. 6 is a circuit diagram showing another example of the resonance frequency switching circuit according to the embodiment of the present invention.

FIG. 7 is a circuit diagram showing a conventional two-band high-frequency oscillation circuit.

[Explanation of symbols]

1, 2, 3, 5, 7 Feedback circuit block 4 Resonance circuit block 6 Two-band resonance circuit block 10 Oscillation transistor 22 Stripline resonator 24 Varactor diode 26, 52, 108, 112 Switching diode 40 Power supply terminal 42 Oscillation frequency Band switching control terminal 43 Tuning voltage supply terminal 75, 76 Strip line resonator 80 High frequency oscillation circuit 1 81 High frequency oscillation circuit 2 82 Coupling circuit 102, 105 Switching switch 103, 104, 106, 110 Strip line resonator

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Nobuo Fuse, Inventor 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Kaoru Ishida 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] 1. An oscillation transistor, a feedback circuit having two or more different impedances for the transistor, and a resonance circuit connected to the transistor and capable of selecting two or more different resonance frequencies. A high frequency oscillation circuit characterized by the above. 2. The high-frequency oscillation circuit according to claim 1, wherein the feedback circuit is an impedance element connected between the collector and the base, between the base and the emitter, and between the emitter and the collector of the transistor. 3. One oscillation transistor and two different oscillation transistors
One or more impedances can be selected, a feedback circuit for the transistor, and connected to the transistor;
And a resonance circuit having two or more different resonance frequencies. 4. The feedback circuit is an impedance element connected between a collector and a base, between a base and an emitter, and between an emitter and a collector of the transistor, wherein at least one of the impedance elements has the impedance. 4. The high frequency oscillation circuit according to claim 3, wherein the selection is made. 5. The device according to claim 2, wherein at least one of the impedance elements has a second capacitance element connected in series to a parallel circuit of the first capacitance element and the inductance element. High frequency oscillation circuit. 6. The high-frequency oscillation circuit according to claim 5, wherein the inductance element is a strip line resonator formed on or in the dielectric substrate. 7. At least one of the impedance elements has a first reactance element, a second reactance element, and a semiconductor switch element for switching between the first reactance element and the second reactance element. The high-frequency oscillation circuit according to claim 4, wherein 8. The high-frequency oscillation circuit according to claim 4, wherein at least one of the impedance elements is connected to a series circuit of the first reactance element and the semiconductor switch element, and the second reactance element is connected in parallel. . 9. The high-frequency oscillation according to claim 1, wherein the resonance circuit has a resonator corresponding to each of the two or more resonance frequencies, and a semiconductor switch element for switching the resonator. circuit. 10. The high-frequency oscillation circuit according to claim 9, wherein the semiconductor switch element is provided between one end of the resonator and a ground. 11. The high-frequency oscillation circuit according to claim 9, wherein the semiconductor switch element is provided between a middle point on the resonator and a ground. 12. The high frequency oscillation circuit according to claim 10, wherein the resonator is a strip line resonator formed on a dielectric substrate or a coaxial dielectric resonator. 13. The high-frequency oscillation circuit according to claim 9, wherein a capacitance element is connected in series between the semiconductor switch element and the resonator. 14. The resonance circuit is a two-band resonance circuit having two desired resonance frequencies. The resonance circuit is formed on a dielectric substrate, and has a first strip line and one end connected to one end. A first capacitor having one end connected to a connection point between the one ends, a second capacitor having one end connected to the other end of the second strip line, A varactor having a cathode connected to the other end and the other end of the second capacitor at the same time, and the other end of the first strip line and an anode of the varactor are grounded. Item 3. The high-frequency oscillation circuit according to Item 3.