JP3405286B2 - Dielectric filter and distortion-compensated amplifier using it - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable group delay time dielectric filter of a distortion compensation type amplifier mainly used in high frequency radio equipment in a high frequency band.

[0002]

2. Description of the Related Art In recent years, a base station radio apparatus of a mobile communication system has come to use a distortion compensation type amplifier for downsizing the base station. FIG. 9 is a block diagram of a feedforward amplifier which is a typical example of the distortion compensation amplifier. The main signal is input from the input terminal 901 and amplified by the main amplifier 906. The signal amplified by the main amplifier 906 causes distortion, and only the distortion component is detected by the distortion detection loop. The feedforward amplifier is the main amplifier 90.
This is a circuit for removing only the distortion component from the signal including the distortion amplified in 6 by the distortion suppression loop and extracting only the signal not including the distortion. Details of the operation are described in JOHN L.
B. WALKER, "High-Power GaA
s FET Amplifiers "(Artech
House (Published by BOSTON, LONDON) 7.3.2 Linearized Amplify
rs. In the distortion detection loop and the distortion suppression loop, since the delay times of the two signals divided by the distributor 904 are made to exactly match and combined by the combiner 905, the delay circuit 903 requires strict fine adjustment of the delay time. .

[0003]

However, since the delay circuit 903 conventionally uses a delay line such as a cable, it is necessary to change the physical length of the cable for fine adjustment of the delay time. Each time it is necessary to remove the connector and disconnect the cable, there is a problem that work efficiency is poor.

In view of the above problems, it is an object of the present invention to provide a delay circuit in which the group delay time can be easily finely adjusted by adjusting only one or a few elements such as a capacitor.

[0005]

In order to solve the above problems, in the dielectric filter of the present invention, a variable capacitor is connected in parallel from two capacitors in series between dielectric coaxial resonators to ground. It is equipped with the configuration.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a view of the inside of a dielectric filter according to a first embodiment of the present invention with a part of upper and lateral walls of the housing removed. In FIG. 1, 1
01 is an input / output terminal, 102 is a dielectric coaxial resonator, 103
Is a coupling substrate made of alumina, 104 is a copper-plated electrode forming a coupling capacitance, 105 is a trimmer capacitor, and 106 is a housing.

The end surfaces of the dielectric coaxial resonator 102 are aligned, and the outer conductors of the dielectric coaxial resonator 102 are grounded to the housing 106.
The inner conductor of the dielectric coaxial resonator 102 is a copper-plated electrode 104.
Are electrically connected to each other with solder or the like. Copper-plated electrode 1 connected to the inner conductor of the dielectric coaxial resonator 102
A trimmer capacitor 105 is connected between 04.
Copper-plated electrodes 104 on both ends of the alumina bonded substrate 103
Is connected to the inner conductor of the input / output terminal 101.

The operation of the dielectric filter having the above structure will be described.

FIG. 2 is an equivalent circuit diagram of the dielectric filter according to the first embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals. 201 is a coupling capacitance on the input / output side formed by the copper-plated electrode 104 in FIG.
In this way, the dielectric coaxial resonator 102 is connected to the coupling capacitor 201.
A band-pass filter can be constructed by combining them respectively.

FIG. 3 shows a trimmer capacitor 1 between stages.
It is a transfer characteristic of the filter when 05 is changed. In this way, when the trimmer capacitor 105 is changed, the pass band width of the filter is changed, and the group delay time characteristic is also changed accordingly.

As can be seen from FIG. 3, the group delay time characteristic 302 has a peak near the pass band edge of the transfer characteristic 301, and the group delay time is less than the peak value within the desired bandwidth 303 between both peaks. Becomes flat. The transfer characteristic when the pass band is widened is 304, and the group delay time characteristic at that time is 305. By widening the pass band, the peak of the group delay time is widened and the flat group delay time is raised to increase the group delay time.

By changing the trimmer capacitor 105 between the dielectric coaxial resonators 102 as described above, the pass band can be widened or narrowed and the group delay time can be varied.

(Second Embodiment) A dielectric filter according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a view of the interior of the dielectric filter according to the second embodiment of the present invention with a part of the upper wall and the lateral wall of the housing removed. In FIG. 4, 401 is an input / output terminal, 402 is a dielectric coaxial resonator, 403 is a coupling substrate made of alumina, 404 is a copper-plated electrode forming a coupling capacitance,
405 is a trimmer capacitor, and 406 is a housing.

The end surfaces of the dielectric coaxial resonator 402 are aligned, and the outer conductors of the dielectric coaxial resonator 402 are grounded to the housing 406.
The inner conductor of the dielectric coaxial resonator 402 is a copper-plated electrode 404.
Are electrically connected to each other with solder or the like. Copper-plated electrode 4 connected to the inner conductor of the dielectric coaxial resonator 402
A trimmer capacitor 405 is connected between the copper-plated electrode 404 between 04 and the ground. The copper-plated electrodes 404 on both ends of the alumina bonded substrate 403 are the input / output terminals 40.
It is connected to one inner conductor.

The operation of the dielectric filter configured as described above will be described.

FIG. 5 is an equivalent circuit diagram of the dielectric filter according to the embodiment of the present invention. The same parts as those in FIG. 4 are designated by the same reference numerals. 501 is an alumina bonded substrate 40.
3 and copper plated electrodes 404 at both ends of the dielectric coaxial resonator 40
2 is the coupling capacitance on the input / output side formed by the copper-plated electrode 404 connected to the inner conductor of No. 2, and 502 is the copper-plated electrode 40 connected to the inner conductor of the dielectric coaxial resonator 402.
4 is the inter-stage coupling capacitance formed by the copper-plated electrode 404 connected to the trimmer capacitor between the four.
In this way, a bandpass filter can be configured by coupling the dielectric coaxial resonator 402 with the coupling capacitance 501 on the input / output side and the coupling capacitance 502 between the stages.

Here, in FIG. 5, the T-type circuit of the trimmer capacitor 405 connected to the ground between the coupling capacitance 502 and the coupling capacitance 502 can be converted into an Π-type circuit as shown in FIG. 6 by equivalent circuit conversion. As the capacitance value C1 of the interstage capacitance 601 of FIG. 6, the value Ca of the trimmer capacitor 405 and the value Cb of the interstage coupling capacitance 502 of FIG. 5 are used.

[0020]

[Equation 1]

Is represented as That is, this is nothing but changing the coupling capacitance between the stages by changing the trimmer capacitor 405. As a result, the group delay time can be changed as in the first embodiment.

As described above, according to the present embodiment, a variable capacitor is provided in parallel with the series capacitor for coupling the dielectric coaxial resonators to the ground, and the capacitor is made variable so that the group delay time is continuously changed. Can be changed to. Also, the delay time can be similarly changed by using the variable capacitor as the variable inductor.

FIG. 7 shows that the Q value indicating the performance of the circuit component is 10
7 shows the transfer characteristics of the circuits of FIGS. 2 and 5 when the variable capacitance of 0 and the capacitance other than the variable capacitance are set to 800.
01 is the characteristic of the circuit of FIG. 2, and 702 is the characteristic of the circuit of FIG. By arranging the variable capacitors in parallel, deterioration of insertion loss is small even if the Q value of the variable capacitors is low.

Further, since the group delay time can be continuously varied, in a feedforward circuit of a distortion compensation type amplifier and the like, adjustment efficiency is improved and productivity and mass productivity are improved.

Although a trimmer capacitor is used as the variable capacitor, a varactor diode 801 is used as shown in FIG.
Is used to change the voltage applied to the choke coil 802, the same effect can be obtained even if the capacitance between the coupling capacitors 502 and the ground is changed.

Although the alumina bonded substrate is used as the bonded substrate in each of the above-described embodiments, the present invention is not limited to this, and a glass epoxy substrate or the like can be used, for example. By using the glass epoxy substrate, the effect of cost reduction can be obtained.

In each of the above embodiments, the copper-plated electrode was used as the electrode, but the present invention is not limited to this, and solder, for example, can be used. By using solder, the effect of cost reduction can be obtained.

Further, in each of the above-described embodiments, the capacitance is the gap between the copper-plated electrodes. However, the present invention is not limited to this, and for example, the capacitance of alumina having copper-plated front and back or a chip capacitor is used. be able to.
By using the capacity made of alumina, it is possible to take measures against discharge between the electrodes when a large amount of electric power is input, and it is possible to obtain an effect that mass production can be enhanced by using the chip capacitor.

In each of the above-described embodiments, the capacitor is mainly used as the reactance element, but the present invention is not limited to this, and for example, an inductor can be used.

[0030]

As described above, according to the present invention, the group delay time is continuously varied by providing a variable capacitor in parallel with the ground from the series capacitor for coupling the dielectric coaxial resonators and varying the capacitor. Can be made. Further, since the group delay time can be continuously varied, the efficiency of adjustment is improved and the productivity and mass productivity are improved in the feedforward circuit of the distortion compensation amplifier.

[Brief description of drawings]

FIG. 1 is a diagram showing the inside of a dielectric filter housing according to Embodiment 1 of the present invention with parts of the upper wall and lateral wall removed.

FIG. 2 is an equivalent circuit diagram of the dielectric filter according to the first embodiment of the present invention.

FIG. 3 is a transfer characteristic and group delay time characteristic diagram of the dielectric filter according to the first and second embodiments of the present invention.

FIG. 4 is a diagram showing the inside of a dielectric filter housing according to a second embodiment of the present invention with parts of upper and lateral walls removed.

FIG. 5 is an equivalent circuit diagram of the dielectric filter according to the second embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit in which a T-type connection of a coupling capacitance and a trimmer capacitor formed between dielectric coaxial resonators of a dielectric filter according to a second embodiment of the present invention is converted into a Π-type connection.

FIG. 7 is a diagram showing a transfer characteristic when the Q value of the variable capacitance of the dielectric filter in the first and second embodiments of the present invention is 100.

FIG. 8 is a diagram showing an equivalent circuit using a varactor diode and a choke coil as a variable capacitor of the dielectric filter according to the second embodiment of the present invention.

FIG. 9 is a block diagram of a conventional feedforward amplifier.

[Explanation of symbols]

101 Input / Output Terminal 102 Dielectric Coaxial Resonator 103 Coupling Substrate 104 Copper Plated Electrode 105 Trimmer Capacitor 106 Housing 201 Input / Output Side Coupling Capacitance 301 Narrow Band Transfer Characteristic 302 Narrow Band Group Delay Time Characteristic 303 Desired Bandwidth 304 Wide Band Transfer characteristic 305 Wideband group delay time characteristic 401 Input / output terminal 402 Dielectric coaxial resonator 403 Coupling substrate 404 Copper plating electrode 405 Trimmer capacitor 406 Housing 501 Input / output side coupling capacitance 502 Stage coupling capacitance 601 Series capacitance 602 Parallel capacitor 701 Transfer characteristic 702 of FIG. 2 using a variable capacitor having a Q value of 100 Transfer characteristic 702 of FIG. 5 using a variable capacitor having a Q value of 100 Varactor diode 802 Choke coil 901 Input terminal 902 Output terminal 903 Delay circuit 904 Distributor 905 Combiner 906 Main amplifier 90 Auxiliary amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Minoru Tachibana, Inventor 55-12 Ohsumihama, Kyotanabe-shi, Kyoto Prefecture Matsushita Nitto Electric Co., Ltd. (72) Toshiaki Nakamura 55-12 Ohsumihama, Kyotana-shi, Kyoto Prefecture Nitto Matsushita Electric Appliance Co., Ltd. (56) Reference JP-A-11-68409 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01P 1/20-1/219 H01P 7/00-7 / 10 H03F 1/32 H03F 3/60

Claims (3)

(57) [Claims] 1. A reactance comprising a plurality of dielectric coaxial resonators, wherein adjacent dielectric coaxial resonators are connected via at least two reactance elements connected in series, and the reactances are connected in series. A dielectric filter, wherein an element and an earth are grounded via a variable reactance element, and a value of the variable reactance element is made variable so that a group delay time in a pass band is made variable. 2. A distortion-compensated amplifier circuit using the dielectric filter according to claim 1 in a delay circuit. 3. The distortion compensating amplifier circuit according to claim 2 , wherein the distortion compensating amplifier is a feedforward circuit.