Research On High Speed Broadband Electronical Tunable Filter Technology

In order to meet the requirements that bandwidth is more bigger and index is getting higher,high performance broadband tunable filter with the advantages of continuous frequency tuning,low cost,small size,easy control,and good for simplifying the system is becoming a research hotspot in the field of communication technology.Among them,the design of using variable capacitance diode to achieve the function of the electronic tuning is the most commonly used and the most cost-effective.In the paper,we studied the method of using varactor and FET tuning,and the modeling,simulation and optimization design were carried out by using the ADS software of Agilent company to realize four broadband high speed tunable filter based on the LC parameters,and the frequency range covering 30MHz~1025MHz.The main work of this paper includes:1?The principle block diagram of high speed tuning filter module based on LC lumped parameter is determined.The high speed electrically tunable filter circuit consists of three parts: LC filter circuit,FET amplifier circuit and DC bias circuit,and the frequency tuning was realized by changing the capacitance of varactor in the circuit,and the signal is amplified by the addition of FET in the signal path to offset loss of LC filter,which made the electrically tunable filter system has a certain gain.2?Using the ADS software of Agilent company to model,simulate and optimize design.In this paper,we designed four wideband high speed tunable filters,and their frequency bands are covering 30MHz~90MHz,90MHz~250MHz,250MHz~500MHz,500MHz~1025MHz respectively.3?Combined with the construction of the frequency band covering 30 MHz ~ 1025 MHz high speed electrical filter.Integrating the four electrically tunable filters with adjacent frequency bands,a high speed and wide band adjustable high speed electrically tunable filter with an adjustable frequency range of 30 times could be obtained.The test results show that the high speed broadband tunable filter can be continuously tuned in the frequency range from 30 MHz to 1025 MHz,and the reflection in the full frequency band is better than-9d B,and the gain is not less than 5dB?...