Circuits, Systems, and Signal Processing

, Volume 31, Issue 5, pp 1577–1597 | Cite as

Comparative Analysis of Tunable Q-Enhancement Filter Cell Topologies in a 2.4 GHz LNA

  • Bogdan Georgescu
  • Joshua Nakaska
  • Ivars Finvers
  • Fadhel Ghannouchi


The special LNA topologies resulting from loading a simple LNA with a set of Q-enhanced inductors are analyzed and compared. The Q of the on-chip spiral inductors that form the LNA load is enhanced by using a negative resistance realized with a cross-coupled differential pair degenerated and biased in various ways. The performance of the LNA is presented for the following types of Q-enhancement circuit: ideal negative resistor (ideal cell), tail-biased non-degenerated cross-coupled differential pair (classic cell), tail-biased resistively degenerated cross-coupled differential pair (resistive cell), tail-biased LC degenerated cross-coupled differential pair (B-cell), self-biased LC degenerated cross-coupled differential pair (BB-cell). The analysis focuses on the benefits of each cell related to s-parameter response, noise and linearity and the interdependency of Q vs. center frequency during tuning. Low voltage design challenges are addressed by presenting the advantages of the novel self-biased LC degenerated cross-coupled differential pair (BB-cell).


LC tank Q-enhancement Tunable circuits LNA 



This work was supported by the Natural Sciences and Engineering Research Council of Canada, the Alberta Informatics Circle of Research Excellence, the University of Calgary, and the Canadian Microelectronics Corporation. Thanks are due to the reviewers for useful comments.


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Bogdan Georgescu
    • 1
  • Joshua Nakaska
    • 2
  • Ivars Finvers
    • 3
  • Fadhel Ghannouchi
    • 1
  1. 1.Department of Electrical and Computer EngineeringUniversity of CalgaryCalgaryCanada
  2. 2.HoustonUSA
  3. 3.CalgaryCanada

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