Research And Design Of Reconfigurable Multifunctional Filter And Its Automatic Tuning Circuit

In recent years, with the rapidly development of RF wireless technology, combining several functions in one wireless transceiver device becomes one of the most innovative and cutting-edge technology which draws more and more attention.The multi-mode and multi-frequency receiving system based on CMOS processes becomes increasingly significant as it is priceless than a single mode receiver. As the key module of the RF receiver in wireless communication system, the filter’s structure and action directly influences the performance of the whole system.The filters must have stable performances, flexible functions, reconfiguration structures and tunable frequencies to meet different requirements in multi-mode and multi-frequency receiver system.Firstly, the design technology and the design method of analog filter at home and abroad are systematically summarized and analyzed in this dissertation. Secondly, several reconfigurable high performance analog filters based on different active devices are proposed. Thirdly, the dissertation further investigates the factors which effect on the filter’s characteristic; these factors mainly include process, environment, and device aging. Finally, a high-accuracy and low signal distortion on-chip auto-calibrating circuit is designed.This dissertation is organized as follows.In chapter2, the basic principles and characteristics of different filters are described and compared. Also the basic theory of automatic tuning circuits is analyzed.In chapter3, a multi-mode and multi-frequency filter based on a high linear OTA is proposed. In this design, the filter’s cutoff frequency can be tuned by changing the trans-conductance of OTA. Different orders low pass, band pass or complex filters can be switched in one circuit topology by rearranging the three group switches in the filters. The simulation results are presented to verify the theoretical prediction and analytical discussion.In chapter4, a high-order current mode multi-functional filter based on DVCC circuit is proposed. This circuit has a simple configuration and good generality; it is easy to be integrated. What’s more, its design method is simple, clear and fully portable. But this filter cannot be adjustable. Therefore, a digital programmable control DVCC:DPDVCC is presented to overcome this disadvantage. The presented filter using DPDVCCs not only has the advantages of that filter based on DVCCs, but also has tunability characteristic. Then, a current-mode high-order multi-functional filter based on CCTA is designed. Different orders low pass, high pass, band pass or notch function can be realized by choosing different input.The parameter coo and Q can be tuned by changing the baise current Is.It has the characteristics of simple structure,minimum components,which is very suitabel for full integration.In chapter5, the influences of the resistors and capacitors on chip caused by the process factors (such as manufacturing tolerances, process variations, temperature drift, etc.) environmental changes (such as temperature, supply voltage), device aging, working conditions, or other factors are emphatically studied,.and the consequent changes of the key performance in filters are discussed furtherly. Then, a high performance on-chip automatic tuning system is designed. This circuit is used to adjust a fully-differential active band-pass filter. As a part of a GPS/beidou dual-mode and dual-band receiver, both of the proposed auto-tuning circuit and band-pass filter are fabricated in0.18μm CMOS process. They occupy a die area of623.40×870.8μm2,and draw5.2mA from a1.8V supply. Both of simulation and experimental results indicate that the circuit suffices specifications of the receiver system.