Design consideration of multi-band RF CMOS filter based on active inductors

In this paper, topology of gyrator-C active inductors are briefly reviewed. A novel structure of multi-band RF active inductor using transistors is presented. Issues of the active inductor related to stability, Q-enhancement principle, and noise are considered. The design of the multi-band Q-enhancement RF filter with 0.18um CMOS process is achieved based on the active inductors. Simulated results show the filter centered at 2.48GHz with about 84MHz bandwidth (3-dB) is tunable in frequency from about 2.19GHz to 4.14GHz, and it exhibits -6.1dBm input third-order intercept point at 2.48GHz with about 80MHz bandwidth while the DC power consumes only 3.9mW.