Tunable bandpass filter using double resistive feedback floating active inductor for 5 GHz wireless LAN Applications

It has been a challenging task for the designers to implement on-chip bandpass filter at high frequency with better performance. In this paper, a tunable RF bandpass filter using double resistive feedback floating active inductor (AI) based on gyrator-C topology has been proposed using 40 nm CMOS technology for 5 GHz WLAN applications. Small signal analytical modelling determines the design parameters affecting the performance of proposed floating AI, which ascertains that the double resistive feedback increases the quality factor as well as inductance value. The proposed AI attains a maximum quality factor of 964, high inductance ranging from 420 to 2080 nH and wide inductive bandwidth varying from 550 MHz to 7.85 GHz. Total current drawn by the AI is 2.66 mA at 1.2 V power supply and occupies an area of 17.1 x 9.1 mu m(2). In order to validate the performance of AI, a second-order tunable bandpass filter with frequency range 5.15-5.35 GHz has been implemented, with a small fractional 3-dB bandwidth, quality factor and 1-dB compression point of 15 MHz, 346 and - 2.8 dBm respectively. The Bandpass filter attains the figure of merit of 92.16 dB and dynamic range of 150 dB-Hz.