QUASI-TRANSMISSION-LINE VARIABLE REACTANCE CIRCUITS FOR A WIDE VARIABLE-PHASE RANGE X-BAND MONOLITHIC PHASE-SHIFTER

This paper describes a novel quasi-transmission-line variable-reactanc e circuit that extends the variable-phase range of phase shifters. It consists of a transmission line and two shunt varactors. By appropriat ely choosing the characteristic impedance and electrical length of the transmission line, the variable-phase range can be significantly incr eased. Since the proposed circuit can be fabricated by the conventiona l MESFET process, a phase shifter can be integrated with other functio nal circuits. This enables fully monolithic integration of RF circuits as a one-chip multi-functional MMIC in radio communication systems. T he variable-phase range of the prototype X-band monolithic phase shift er is 208 degrees, which is approximately four times as large as that of conventional one.