Ultra compact, low loss, varactor tuned phase shifter MMIC at C-band

This paper presents a high yield, ultra compact, low loss phase shifter MMI C, realized with a commercial 0.6 mum GaAs MESFET process. Phase shift is e nabled by varying the varactor capacitances of the lumped element equivalen t of a transmission line. Continuously adjustable phase control over 90 deg rees is achieved from 4 GHz up to 6 GHz, with a loss of less than 2.2 dB, A t 5.2 GHz, a loss of 1.2 dB and a loss variation of +/-0.5 dB is measured. Phase and loss variations for several circuits from different wafers are wi thin +/-1 degrees and +/-0.1 dB, respectively, indicating low dependences o n process variations. The phase shifter requires a circuit size of only 0.2 mm(2), which to our knowledge is the smallest size for a continuously adju stable passive phase shifter with comparable performance, reported to date.