A new structure for reflection-type phase shifter with 360/spl deg/ phase control range

Abstract

A novel 360/spl deg/ reflection type phase shifter is proposed. It comprises a 3-dB coupler, resonant circuits, transistors and PIN diodes. The control of phase is enabled by controlling the capacitance of the varactor (transistor). The new structure provides a full 360/spl deg/ phase shift and it is believed that it can be extended to phase shifts even beyond 360/spl deg/. Equations are derived to precisely describe the behavior of the reflective load, the range of obtainable phase shifts as well as the limitations imposed by such a structure. In one case it is shown that with a careful choice of the varactor the transmission losses can be kept to lower than 2.6 dB. Also, in another case the phase control range of 360/spl deg/ is obtained using a bipolar transistor with a capacitance ratio (c/sub max//c/sub min/ ) of only 1.28.