Original Application of Stop-Band Negative Group Delay Microwave Passive Circuit for Two-Step Stair Phase Shifter Designing

This paper investigates on the theorization, design, fabrication and measurement of original phase shifter (PS) operating with two-step stair phase behavior. The innovative stair PS is designed with unfamiliar stop-band (SB) negative group delay (NGD) passive circuit. The elementary unfamiliar SB-NGD topology constituted by resistive, inductive, and capacitive lumped network is described. Acting as an RF and microwave circuit, the S-matrix model is expressed in function the RLC-network parameters. Thus, the canonical form of unfamiliar SB-NGD transfer function (TF) represented by the transmission coefficient is established. The unfamiliar SB-NGD circuit equations in terms of the NGD parameters are formulated. The established theory is validated comparing the calculated, simulated, and measured S-parameters and group delays (GDs). Results with a very good agreement showing unfamiliar SB-NGD behavior are observed around the central frequency 2.45 GHz and bandwidth of 100 MHz. An innovative application of unfamiliar SB-NGD function for the communication system front-end is developed. The developed application concept of unfamiliar SB-NGD circuit is illustrated by designing a microwave device operating as a PS presenting a two-step stair response completely original behavior. The basic theory, design and implementation of the two-step stair PS concept are introduced. To validate the two-step stair PS principle, a proof of concept (PoC) is designed based distributed element based inductive and capacitive microstrip elements. The simulated and measured results of the PS PoC are in good agreement. The experimental results confirm the feasibility of two-step stair PS with phase jumping from -70 degrees +/- 4 degrees (from 2 GHz to 2.3 GHz) to -104 degrees +/- 2 degrees (from 2.6 GHz to 3.0 GHz). The investigated unfamiliar SB-NGD function-based stair PS is promising for future development 5G and 6G communication system.