The Research Of Group Delay Regulation Based On Active Circuit

Design of traditional wireless communication systems only need to focus on amplitude frequency characteristic of the signal.However,with the rapid development of communication technology in recent years,the flatness of group delay needs to be considered in the design of various devices to further improve the performance of communication system.In order to optimize and control the group delay of the device and system,the concept of group delay regulation is proposed.Group delay regulation is a key component of a communication system that achieves higher transmission rates and bandwidths.Based on the concept of group delay regulation,a new type of communication system that is different from digital communication can be realized.The actualization of the group delay regulation is based on the circuit structure that generates time delay.After investigating the literature about group delay regulation and engineering,this paper chooses to realize group delay regulation based on the concept of electromagnetic induced transparency(EIT).Then active circuits are loaded to the EIT-like strcture to greatly increase the amount of group delay.The group delay control precision,range and flexibility are also improved.The main work and innovations of this paper are as follows:1.The basic principle and circuit model of electromagnetically induced transparency effect is studied in this paper.According to the design principle of EIT-like effect,a microstrip structure that generate EIT-like effect is proposed,which can realize several ns group delay in the pass band.2.The loss analysis of the passive circuit is performed by microwave network analysis and theoretical calculation,and the performance of three kinds of single-port negative resistance circuits based on FET is compared by simulation.The negative resistance circuit is loaded on the microstrip EIT-like structure to further improve the passband group dela,and the regulation of the passband group delay is realized by the bias voltage of the negative resistance circuit.3.The theory of how the active resonator improves the Q value of the resonator is discussed.And an active resonator is used for the design of EIT-like structure.The passband group delay of the EIT-like structure is significantly improved.The two bias voltages of the amplifier can be applied to the linear regulation of passband group delay with high precision.Then a four-band active group delay regulation is implemented based on the multi-bandEIT-like effect.4.Taking advantage of the feature that the group delay of active EIT-like structure is sensitive to the phase change of the capacitor loaded on the active feedback loop,a high precision group-delay-based active capacitive sensor is designed and tested.5.A structure that generates multi-band EIT-like effect is realized in millimeter-wave band.The variation of the coupling distance of the metal DUT and the multi-band EIT-like structure can independently affect the frequecies of the passband.So a high-performance balanced sensor is simulated and tested.