1. An Integrated Solution for Suppressing WLAN Signals in UWB Receivers LI BO

2. Motivation UWB system becomes more interested in Wireless Personal Area Networks (WPAN) due to its high bandwidth after federal release the unlicensed spectrum in 3.1-10.6 GHZ Wireless Local Area Network (WLAN) is operated in 4.9-5.825 GHZ

3. Intermodulation products in UWB Band

4. Suppressing WLAN signal Third-order intermodulation Second order intermodilation It is a natural idea to suppress WLAN and other noise to improve performance

5. Possible solutions Off-chip pre-filter  Increase cost due to additional external component  signal lost  lower speed Integrate a filter to avoid WLAN interferers  Increase speed  Low cost

6. Wide-band filter VS tunable narrowband filter Wide-band  High order filter Need many inductor ( a lot of space) Impairs gain of receiver Tunable narrowband filter  Can be easily implemented through low order filter  Must have tuning due to small band

7. Tunable narrowband filter receiver scenario

8. Low Noise Amplifier (LNA) LNA will determine noise figure of receivers Challenges in design LNA  Input resistor need to be 50 ohms  Very low noise figure  Gain with high linearity which often measured in IP3  Maximize output power

9. Low noise amplifier (LNA) L 1,C 1,L 2 C 2 use for matching Inductively degenerated common- source amplifier Lg is added to give flexibility to design\ Cascode circuit to imporve frequency response

10. Notch filter simple example At resonant frequency, Zf is equal to zero so steal all signals

11. Notch Filter design Two resonant frequency Q4 works as a negative resistor It is tunable through varactor

12. Mixer A multiply circuit R3,L4 are use to isolate RF signal L4 is 5 nH, an area of 70x70 um 2

13. LO input and output buffer

14. Chips Due to Sidewall capacity of pad

15. Measured noise figure (NF) Parasitic resistance of notch filter Poor model and layout of the varactor

16. Measured results

17. Performance

18. Conclusion Implement tunable filter idea to suppress WLAN inference in 4.9-5.825 GHZ using SiGe 0.35um technology The LNA, Mixer and filter power consumptions are 25.2,6 and 18 mW. The NF is not coherent with design which maybe due to poor model and layout of varactor