Design of low power low noise tunable active inductors for multiband RF front end communication circuits

This paper presents low power tunable active inductors suitable for designing multiband RF front end communication circuit like LNA, BPF and VCO. The active inductor circuit uses PMOS cascode structure as negative transconductor of a gyrator to reduce the noise voltage. Also, this structure provides possible negative resistance to reduce the inductor loss with wide inductive bandwidth and high resonance frequency. To improve the quality factor, a MOS transistor is used as a feedback resistor between the positive transconductor and the negative transconductor. The tuning of quality factor and center frequency for multiband operation is achieved through the controllable current sources. The tunable range of the active inductors varies from 3.9 GHz to 12.3 GHz (without feedback transistor) with the power consumption of 0.6mW and 3.9GHz to 16GHz (with feedback transistor)with the power consumption of 0.65mW. The noise voltage varies from 21nV/√Hz to 7nV/√Hz for the active inductor without feedback transistor and from 12n V/√Hz to 5.612n V/√Hz for the active inductor with feedback transistor. The designed active inductors are simulated in 180nm CMOS process using Synopsys HSPICE tool.