The advent of highly integrated wireless transceivers is a platform for the research and development of active LC filters on silicon chips. The design of such filters presents great challenges to designers. The quality of on-chip reactive components is the main reason for this, since the losses and the parasitics in those components can result in frequency response distortion, and the need for active components, like negative resistors, limits dynamic range. Nevertheless, the performance already achievable may be sufficient for the implementation of such filters in certain parts of the transmitter, e.g. at the output of mixers, where a large signal must be bandpass-filtered. Many improvements are needed, and can be expected in the future, in the realisation of higher quality on-chip inductors and capacitors, in filter synthesis when the reactive component losses are large, in the accurate compensation of such losses using negative resistances, in the implementation of those resistances with low noise and high linearity, and in the automatic tuning of on-chip active LC filters.
Active filters using integrated inductors, Page 1 of 2
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