JPH04276916A - Active resonator - Google Patents

Abstract

PURPOSE:To improve an IM without increasing an output noise by inputting part of an output power of a feedback amplifier circuit to a resonator element from an input side. CONSTITUTION:An output power of a feedback amplifier circuit 20 in the active resonator 10 is inputted to a resonator element 12 via an output capacitor 24. Part of an output current of the circuit 20 is fed to a circulator 28 via a phase shift circuit 30 by a directional coupler 26 and inputted to the element 12 via an input capacitor 22. The output power of the circuit 20 is inputted to the element 12 from both the input and the output sides. Since the input power to the circuit 20 is reduced, even when an external Qe1 is set small, it has an effect of increase sufficiently, then the IM is improved. Since an external Qe2 is set large, an output noise of the resonator 10 itself is not increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active resonator, and more particularly to an active resonator used as a high frequency band rejection filter in the GHz band, for example.

0002

2. Description of the Related Art Referring to FIG. 2, a conventional active resonator 1 includes a dielectric resonator 2. As shown in FIG. In the dielectric resonator 2, a feedback amplifier circuit 4 including an amplifier 3 is connected to an input capacitor 5 having an external Qe1 and an output capacitor 6 having an external Qe2.
They were coupled by an electric field.

0003

[Problems to be Solved by the Invention] In order to reduce the output noise in such an active resonator 1,
Although it is sufficient to increase the external Qe2, the active resonator 1
In order to increase the no-load Q0 of
must be made smaller. However, if the external Qe1 is made smaller, the power input to the feedback amplifier circuit 4 becomes larger, and IM (intermodulation distortion) becomes larger. On the other hand, external Q
If e1 is made larger, IM becomes smaller, but at this time, external Qe2 must be made smaller, so output noise becomes larger, and there is a problem in either case.

[0004] Therefore, the main object of the present invention is to provide an active resonator that can improve the IM without increasing the output noise.

[0005]

[Means for Solving the Problems] In an active resonator including a resonator element and a feedback amplifier circuit coupled to the resonator element, part of the output power of the feedback amplifier circuit is input to the feedback amplifier circuit. It is an active resonator characterized by input to the resonator element from the side.

[0006]

[Operation] For example, a directional coupler is inserted on the output side of the feedback amplifier circuit, a circulator is inserted on the input side of the feedback amplifier circuit, and the directional coupler and the circulator are connected by a phase circuit. Then, the output power of the feedback amplifier circuit is input to the resonator element from the output side of the feedback amplifier circuit, and a part of the output power of the feedback amplifier circuit is separated by the directional coupler and sent to the feedback amplifier via the circulator. The input to the resonator element is from the input side of the circuit. Therefore, the power input to the feedback amplifier circuit is reduced.

[0007]

According to the present invention, since the power input to the feedback amplifier circuit can be reduced, the IM can be reduced without increasing the output noise. The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an active resonator 10 of this embodiment is used, for example, as a high frequency band rejection filter in the GHz band, and the active resonator 10 as a whole has an unloaded Q0. Active resonator 10 includes a resonator element 12 made of, for example, a dielectric resonator. The resonator element 12 includes a phase circuit 14,
A feedback amplifier circuit 20 is connected which includes a series connection of an amplifier 16 and a phase circuit 18. That is, the feedback amplifier circuit 20
The input side of the feedback amplifier circuit 20 is electrically coupled to the resonator element 12 by an input capacitor 22 having an external Qe1, and the output side of the feedback amplifier circuit 20 is electrically coupled to the resonator element 12 by an output capacitor 24 having an external Qe2. Here, as in the conventional case, the external Qe1 of the input capacitor 22 is
is set large and the external Qe2 of the output capacitor 24 is set small.

A directional coupler 26 is inserted on the output side of the feedback amplifier circuit 20, that is, between the phase circuit 18 and the output capacitor 24. Further, a circulator 28 is inserted on the input side of the feedback amplifier circuit 20, that is, between the phase circuit 14 and the input capacitor 22. Directional coupler 2
6 and the circulator 28 are connected via a phase circuit 30.

Active resonator 1 formed in this way
0, the output power of the feedback amplifier circuit 20 is input to the resonator element 12 through the output capacitor 24. At this time, a part of the output power of the feedback amplifier circuit 20 is separated by the directional coupler 26. That is, a portion of the output power is sent by the directional coupler 26 to the circulator 28 via the phase circuit 30. This output power is then input to the resonator element 12 through the input capacitor 22. Therefore, the output power of the feedback amplifier circuit 20 is transmitted to the resonator element 1 from both the input side and the output side of the feedback amplifier circuit 20.
2 is input.

[0011] In this way, by inputting power to the resonator element 12 from the input side of the feedback amplifier circuit 20, the power input to the feedback amplifier circuit 20 is reduced, so that the external Qe1 can be reduced as in the conventional case. Even if it is set, the effect is substantially the same as that of increasing the external Qe1, and IM can be improved. Further, since the external Qe2 is set large as in the conventional case, the output noise of the active resonator 10 itself does not increase.

As an experimental example, when the unloaded Q0 of the resonator element 12 is increased from approximately 5,000 to over 50,000, and the gain of the amplifier 16 is set to 10 dB, the peak value of the output noise is changed. The input power of the amplifier 16 can be reduced by approximately 3 dB without any interference, and the third-order IM level can be reduced by approximately 9 dB.
Can be reduced by dB.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a prior art.

[Explanation of symbols]

10...Active resonator 12...Resonator element 20...Feedback amplifier circuit 26...Directional coupler 28...Circulator

Claims (1)

[Claims] 1. An active resonator including a resonator element and a feedback amplifier circuit coupled to the resonator element,
An active resonator, characterized in that a part of the output power of the feedback amplifier circuit is input to the resonator element from an input side of the feedback amplifier circuit.