Leakage power minimization in ultra wideband uwb communications circuits
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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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Leakage power minimization in ultra wideband uwb communications circuits

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

Edgar Wangolo


Presentation plan

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

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


Uwb vs narrowband communications

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


Leakage power minimization in ultra wideband uwb communications circuits

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


Uwb spectrum

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)


Uwb vs narrowband

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


Uwb advantages

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


Uwb applications

UWB: Applications

  • Accurate positioning (through wall radar, tracking)

  • High quality wireless video

  • Satellite communications

  • Air traffic control

  • Medical imaging

  • Etc.


Pll block diagram

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.


N digit fractional n prescaler

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


Circuit power

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.


Leakage power sources

Leakage Power Sources

Sub-threshold

Gate oxide

PN


Leakage control mtcmos

Leakage control: MTCMOS


Smart switch series triple s

Smart Switch Series (Triple-S)


Rcsff reduced clock swing flip flop

RCSFF: Reduced-Clock Swing Flip-Flop


Timetable

Timetable

  • Literatures:March 10

  • Circuit Design:March 16

  • Simulations:March 28

  • Presentation:April 6

  • Report:April 20


References

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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