Monolithic tunable active inductor with independent Q control

A 1.1-GHz fully integrated GaAs MESFET active inductor is presented in this paper. Both the inductance and loss resistance are tunable with the inductance independent of series loss tuning. The measured loss resistance is tunable over a -10- to +15-Ω range with a corresponding change in inductance of less than 10% at 100 MHz and less than 4% for frequencies above 500 MHz. The inductance is tunable from 65 to 90 nH. Considerably larger bandwidths can be achieved depending on the fabrication technology employed and the intended application of the circuit