Performance Analysis of Tunable Band Pass Filter and VCO for Multiband RF Front End

This paper presents a design and performance analysis of tunable RF front end circuits such as RF band pass filter and VCO for multiband applications. The tunable element is an active inductor, built by MOS transistors. It is attractive due to its tunable and larger inductance values. The RF band pass filter is realized using active inductor with suitable input and output buffer stages. The tuning of center frequency for multiband operation is achieved through the controllable current source of the active inductor. The tunable range of the band pass filter varies from 3.9 GHz to 12.3 GHz. The simulation results of band pass filter have minimum noise figure of 23 dB and has less power dissipation of 2.83mW. The simulated IIP3 is -9.6dBm for 1st and 3rd order frequency of 7.94 GHz and 7.93 GHz respectively. The VCO designed using active inductor has the tuning range of 0.384 GHz to 1.620 GHz with the phase noise of -139dBc/Hz at the offset of 1MHz. It consumes less power of 1.754mW with the figure of merit of 189dBc/Hz. The designed active inductor, RF band pass filter and VCO are simulated in 180nm CMOS process using Synopsys simulation tool.