Phase shifters are omnipresent in telecommunications. They play an important role in radar, phased array and receiver systems. Reflective-type Phase Shifter (RTPS) circuits, with inherently well-impedance matched inputs/outputs are of particular interest for applications where high phase shift values, excellent performance and small size are of importance.
A novel 360o reflection type phase shifter is proposed in this paper. 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) and the switching behavior of the PIN diode.. The new structure provides a full 360o phase shift, and it is believed that it can be extended to phase shifts even beyond 360o. Equations are derived to precisely describe the behaviour 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 360o is obtained using a bipolar transistor with a capacitance ratio (Cmax/Cmin ) of only 1.28.
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