A TUNABLE BANDPASS FILTER USING Q-ENHANCED AND SEMI-PASSIVE INDUCTORS AT S-BAND IN 0.18-μM CMOS

Abstract

A fully-integrated bandpass fllter using Q-enhanced and semi-passive inductors is design, implemented and verifled experimentally in a standard 0.18-m CMOS process. The inductors achieve high-Q factors by using a tapped-inductor feedback technique to produce negative resistances. Compared with conventional transformer feedback, the proposed technique not only compensates resistive losses with low-power consumption but also provides a high- inductance inductor which is suitable for low-frequency applications. The 2-pole Chebyshev series-C coupled bandpass fllter provides a frequency tuning range of 300MHz around 2.65GHz. Measurements shown that it consumes 2.4 mW to achieve 1.0-dB insertion loss, 12- dB return loss, 6.3-dB noise flgure, and i2:5-dBm input P1dB with a 950-MHz bandwidth at 2.8GHz. And it consumes 5.6 mW to achieve 1.5-dB insertion loss, 10-dB return loss, 7.9-dB noise flgure, and i4- dBm input P1dB with a 700-MHz bandwidth at 2.5GHz. The overall chip size of the fllter is 0:7mm £ 0:9mm including all testing pads.