Voltage controlled phase shifters on CMOS technology

Implementation of voltage controlled active inductors on standard CMOS technology for 2GHz is described. The circuit is based on a gyrator implemented with a 5 MOSFETs feedback circuit, including the DC bias. Theoretical expressions were derived with a simple but enough accurate MOSFET model. The inductor value is controlled by an auxiliary bias voltage Vtune. An MMIC with a CMOS standard technology was designed, fabricated and tested. At 2GHz, an L=35nH inductor with a Q≈7 and a series resonant frequency of 2.6GHz was measured. For ΔVtune=1.2V, the inductor value changes from 23nH up to 70nH. A phase shifter application was studied: 45° of phase shift per second order section was achieved.