Wideband Phase Shifter Using 3 Types of LC Resonant Circuits for Phase Slope Alignment

Abstract

This paper proposes a new wideband phase shifter, aligning phase slope between the reference line and main line to reduce the slope deviation using 3 types of LC resonance circuits (series, parallel and composite type). Compared to the conventional ones, the proposed phase shifters have several advantages such as a simple structure with single layer, accurate LC values from the derived formulas that are not optimization values. In addition, any phase shift value is applicable to the proposed theory, since the phase shift range of the proposed phase shifter can be implemented from 0 to 360 degree. The design theory of the proposed phase shifter is derived by taking a differential of difference between reference line and LC resonant circuit with respect to angular frequency, then calculate the value of each element of L and C at the center frequency. Although the proposed phase shifter is designed with only one or three resonant circuits in this paper, the number of resonant circuits constituting the main line can be three or more. By the design theory, the total sum of the phase values allocated to each resonant circuit may be a phase shift value to indicate a desired phase difference between the reference line and the main line. To validate the design theory, 180○ wideband phase shifters with singles (series and parallel) and composite resonant circuits are designed, fabricated, and measured. The fractional bandwidth of the proposed circuits for a parallel and a composite resonant circuit are both greater than 64%. Therefore, the measurement results agree well with the design theory within 0.5 dB insertion loss ±10° and phase deviation, except fabrication error.