A simple reconfigurable BiCMOS active inductor and its implementation in a phase-shifter unit cell

An active inductor based phase-shifter unit cell is proposed. The active inductor is designed with BiCMOS process technology and is implemented with only one heterojunction bipolar transistor and one field-effect transistor without any requirement of complicated transconductance amplifier designs. A phase-shifter unit cell is implemented with a high-pass T-Section with two varactors in series and the active inductor as a shunt. Relative phase variation is achieved by tuning the active inductor or by varying the effective junction capacitance of the varactors. Maximum relative phase variations of 23.7° and 38.6° are achieved at 4 GHz by exclusively tuning the gate voltage and varactor capacitance, respectively. The relative phase variations at 18 GHz are 6.0° and 8.5°, respectively, for the same exclusive conditions.