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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

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

Edgar Wangolo


Presentation plan
Presentation Plan Communications Circuits

  • 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 Communications Circuits

  • 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 Communications Circuits

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


Operation Principles (“Spectrum Underlay“) Communications Circuits

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 Communications Circuits

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: Communications Circuits

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 Communications Circuits

  • 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 Communications Circuits

  • Accurate positioning (through wall radar, tracking)

  • High quality wireless video

  • Satellite communications

  • Air traffic control

  • Medical imaging

  • Etc.


Pll block diagram
PLL Block Diagram Communications Circuits

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 Communications Circuits

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 Communications Circuits

  • 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 Communications Circuits

Sub-threshold

Gate oxide

PN


Leakage control mtcmos
Leakage control: MTCMOS Communications Circuits


Smart switch series triple s
Smart Switch Series (Triple-S) Communications Circuits


Rcsff reduced clock swing flip flop
RCSFF: Reduced-Clock Swing Flip-Flop Communications Circuits


Timetable
Timetable Communications Circuits

  • Literatures: March 10

  • Circuit Design: March 16

  • Simulations: March 28

  • Presentation: April 6

  • Report: April 20


References
References Communications Circuits

  • 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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