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A Tunable Bandpass Filter Using Q-Enhanced and Semi-Passive Inductors at S-Band in 0.18-μm CMOS

By Sen Wang and Rui-Xian Wang
Progress In Electromagnetics Research B, Vol. 28, 55-73, 2011


A fully-integrated bandpass filter using Q-enhanced and semi-passive inductors is design, implemented, and verified experimentally in a standard 0.18-μm 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 filter provides a frequency tuning range of 300 MHz around 2.65 GHz. Measurements shown that it consumes 2.4 mW to achieve 1.0-dB insertion loss, 12-dB return loss, 6.3-dB noise figure, and --- 2.5-dBm input P1dB with a 950-MHz bandwidth at 2.8 GHz. And it consumes 5.6 mW to achieve 1.5-dB insertion loss, 10-dB return loss, 7.9-dB noise figure, and --- 4-dBm input P1dB with a 700-MHz bandwidth at 2.5 GHz. The overall chip size of the filter is 0.7 mm×0.9 mm including all testing pads.


Sen Wang and Rui-Xian Wang, "A Tunable Bandpass Filter Using Q-Enhanced and Semi-Passive Inductors at S-Band in 0.18-μm CMOS," Progress In Electromagnetics Research B, Vol. 28, 55-73, 2011.


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