Design techniques for automatically tuned integrated gigahertz-range active LC filters

This paper discusses design techniques for integrated active LC filters. Issues related to prototype selection, Q enhancement, and automatic tuning are considered. Two designs, both of which are automatically tuned fourth-order bandpass filters in the 2-GHz range, were implemented to demonstrate the proposed techniques and to evaluate the potential of such filters. Measurement results show that modest dynamic range, suitable for certain stages in transmitter applications, is achieved, along with stable response thanks to the on-chip automatic tuning system.