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Leakage Power Minimization in Ultra-wideband (UWB) Communications Circuits

Leakage Power Minimization in Ultra-wideband (UWB) Communications Circuits. Edgar Wangolo. Presentation Plan. UWB: concept and applications Leakage power in sub-micron CMOS Leakage minimization techniques Application to PLL’s Prescaler Project time table References. UWB - Concept.

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Leakage Power Minimization in Ultra-wideband (UWB) Communications Circuits

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  1. Leakage Power Minimization in Ultra-wideband (UWB) Communications Circuits Edgar Wangolo

  2. Presentation Plan • UWB: concept and applications • Leakage power in sub-micron CMOS • Leakage minimization techniques • Application to PLL’s Prescaler • Project time table • References

  3. UWB - Concept • FCC: bandwidth is more than 25% of a center frequency or more than 1.5 GHz • Typically implemented in a carrierless fashion • Directly modulate an “impulse” with a very sharp rise and fall time => a waveform that occupies several GHz • Historically started with radar applications for military use

  4. Time-domain behavior Frequency-domain behavior 1 1 0 Impulse Modulation Ultrawideband Communication frequency time 3 10 GHz (FCC Min=500Mhz) 1 0 1 0 Narrowband Communication Frequency Modulation 2.4 GHz UWB Vs. Narrowband Communications

  5. Operation Principles (“Spectrum Underlay“) Narrowband (e.g GSM: +35 dBm/MHz) Transmit Power Spectral Density [dBm/MHz] WCDMA (typ. +15 dBm/MHz) UWB (e.g – 41 dBm/MHz) 1 Frequency/GHz 10 Bandwidth (GSM : WCDMA : UWB) ~ 1 : 10 : 10000 4

  6. GPS UWB Spectrum • FCC ruling permits UWB spectrum overlay Bluetooth, 802.11b Cordless Phones Microwave Ovens 802.11a Emitted Signal Power PCS “Part 15 Limit” -41 dBm/Mhz UWB Spectrum 1.6 1.9 2.4 3.1 5 10.6 Frequency (Ghz)

  7. ANALOG: I A/D DIGITAL: LNA MIXER Q A/D F SYNTH D/A PA MIXER D/A UWB Vs. Narrowband UWB Transceiver ADC GAIN CLK DIGITAL TX Narrowband Transceiver

  8. UWB: Advantages • High Bandwidth, high data rate • Low power spectral densities • Simple, low cost • Immunity to interference Challenges: • Low/Medium Range • Signal to noise ratio is still an issue

  9. UWB: Applications • Accurate positioning (through wall radar, tracking) • High quality wireless video • Satellite communications • Air traffic control • Medical imaging • Etc.

  10. PLL Block Diagram 30 – 40% of total power PFD up Charge Pump Loop Filter VCO input output down %N 40% of total power Today’s monolithic PLL’s use Phase Frequency Detectors (PFD), charge pumps, and an optional frequency divider in the feedback path.

  11. N-digit Fractional-N Prescaler Fout Fin 2/3 2/3 2/3 2/3 Pn P1 P2 P0 N=2n+2n-1Pn-1+2n-2Pn-2+…+2P1+P0

  12. Circuit Power • Dynamic Power: determined by circuit performance requirement. • Short_Circuit Power: Both PU and PD circuit partially conduct. Small percentage. (<10%) • Leakage Power: Increasingly important, and many issues dependent, such as device geometry, temperature, doping, processing and data pattern dependent, etc. It is very complicated and worthy to study more to improve it.

  13. Leakage Power Sources Sub-threshold Gate oxide PN

  14. Leakage control: MTCMOS

  15. Smart Switch Series (Triple-S)

  16. RCSFF: Reduced-Clock Swing Flip-Flop

  17. Timetable • Literatures: March 10 • Circuit Design: March 16 • Simulations: March 28 • Presentation: April 6 • Report: April 20

  18. References • Hiroshi Kawagushi and Takayasu Sakurai, “A Reduced Clock-Swing Flip-Flop (RCSFF) for 63% Power reduction”, IEEE Journal of Solid State Circuits, Vol. 33, N05, May 1998 • Tschanz et. Al, “Dynamic Sleep Transistor and body bias for active leakage power control of microprocessor”, IJSSC, Nov 2003 • J. T. Kao and A. Chandrakasan, “ Dual Threshold Voltage Techniques for Low-Power Digital Circuits”, IEEE Journal of Solid-State Circuits, July 2000

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