The capabilities extension of electronic tuning filters with solid-state construction
Solid-state filters with the electric tuning of frequency are the key elements of different multifrequency communication systems possessing increased noise immunity and reliability. It is considered considerable part of perspective communications, including to cellular telephony, will use these filters mainly. This development is the electric tunable filters with the improved responses for the perspective communication equipment, it is sent to development of new element base of Ukraine in area of radio electronics.
The new approach to the electric tunable multiresonator filters with symmetric gain-frequency characteristic is developed.
This approach is based on application in the filters of different types of microwave resonators and also use in the resonators of a few blocks that include the different amount of varicaps pairs. Blocks commutation is realized MEMS switches or p-i-n diodes. This approach allows to improve filters functional possibilities: to decrease of losses and intermodulation distortions of signals; to increase operating power; to extend the retuning range; to find symmetry of frequency characteristic.
Bandness degree limitations of the microwave resonators tuned by a few capacities and inductances are set. It is well-proven at the combined retuning it is possible to carry out the change of resonant frequency in a wide rang exceeding a decade.
The new effect of crossing of resonant areas corresponding to the different vibrations in resonators from the transmission line segments with capacity retuning is set. It is shown that during work on the first three resonant frequencies the frequency continuous retuning band can exceed two octaves.
It is shown the combined frequency retuning of dual-mode vibrations by means of capacity and inductances the sizes of that must be bound by a certain condition will be realized in the resonators of loopback type. In the resonators of loopback type with a loop frequency retuning of dual-mode vibrations comes true through two capacities synchronously changing on a certain law.
Engineering design procedure of new filters with the extended functional possibilities is worked out.
The considerable volume of experimental researches of new filters (8 experimental standards) is executed.
Experimental standards on its characteristic exceed the best world analogues: the filter losses on central frequency are diminished in 1.8 time (with 9 dB to 5 dB); intermodulation distortions ratio third to the order IP3 is increased on 16 dBm, with 10 dBm to 26 dBm; operating power is increased with 1 mW to 40 mW; operating frequency is enhanceable in 1.6 time (from 1000 MHz to 1600 MHz); the coefficient of the covering is increased from 2 units to 2.4; filters gain-frequency characteristic symmetry is improved - the asymmetry index is diminished from 1.4 to 1.1.
The new filters frequency characteristic features are set, and recommendations on their application are given.