Research Of RF Reconfigurable Filter Using Memristor

RF filter is an indispensable passive component of RF front-end.With the development of composite reconfigurable wireless network,muiti-band,multi-mode and reconfigurable RF filter has become a current attractive topic.Memristor is a passive two-port tuning device,which has non-volatility,good linearity and low power consumption.It can replace the existing active tuning devices to improve the performance of filter.This paper proposes the design method of reconfigurable filter using memristors,and designs several highperformance RF filters.First,this paper analyzes the basic characteristics of RF reconfigurable filter using memristors.Combining with the theory of filter reconfigurable technology,the synthesis process of RF filter loaded with memristors is studied,which establishes the foundations for the simulation and physical realization of this filter.This paper proposes an improved memristor circuit using SPICE software(an improved memristor SPICE model)based on Hewlett-Packard(HP)memristor,and several reconfigurable RF filters are designed by using the proposed SPICE model.The reconfigurable negative group delay filter using memristors is composed of short-circuit coupled lines,memristors’ tuning circuits and J-type converter.The input / output matched circuits are used to improve the loss characteristics.At the same time,the varactor diodes are utilized to keep the center frequency of the filter at 1.920 GHz,and the maximum tunable range of negative group delay is-2.214 ～-9.029 ns.Furthermore,the bandpass-to-bandstop transformation of reconfigurable bandpass-to-bandstop filter using memristor can be realized by changing the resistance state of memristor.The center frequency of this filter in bandpass mode are continuously tunable between 3.41 GHz and 3.63 GHz,and return loss is better than 22.18 dB.When this filter is switched to bandstop mode,the center frequency of stopband can be flexibly adjusted from 3.41 GHz to 3.62 GHz,with rejection level higher than21.34 dB.Combining with characteristics of the physical memristor(Pi’s model),this paper studies the performance of one switchable dual-band filter using memristors and another switchable dual-band filter with PIN diodes.The comparison results show that Pi’s model has lower loss and better linearity as a tuning device of reconfigurable RF circuit.In addition,this paper also designs a switchable tri-band bandpass filter based on Pi’s model.The proposed filter has four switchable modes: tri-band,dual-band,single-band and full-stopband working mode.The impedance characteristic of memristor can be tuned by the bias voltage to realize the switchable function of filter,which further expands the application of memristor in the reconfigurable filter field.In this paper,memristor is mainly used as an RF tuning device to design reconfigurable filters.The design and implementation method of the reconfigurable filter using memristors is studied,which verifies that memristor has great potential as a tuning device of reconfigurable filter from theoretical analysis and alternative testing.At the same time,this paper presents several high-performance reconfigurable filters using memristors,which have great significance for expanding the application of memristor in RF passive circuits.