Reconfigurable Ultra Low Power LNA for 2.4GHz Wireless Sensor Networks
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Reconfigurable Ultra Low Power LNA for 2.4GHz Wireless Sensor Networks. TarisT., Mabrouki A., Kraïmia H., Deval Y., Begueret J-B. Bordeaux, France . OUTLINE. Context RF Front End Specifications Circuit design Conclusion & Perspectives. OUTLINE. Context RF Front End Specifications

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Reconfigurable Ultra Low Power LNA for 2.4GHz Wireless Sensor Networks

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Reconfigurable Ultra Low Power LNA for 2.4GHz Wireless Sensor Networks

TarisT., Mabrouki A., Kraïmia H., Deval Y., Begueret J-B.

Bordeaux, France


OUTLINE

  • Context

  • RF Front End Specifications

  • Circuit design

  • Conclusion & Perspectives


OUTLINE

  • Context

  • RF Front End Specifications

  • Circuit design

  • Conclusion & Perspectives


Context

MicroElectronicMilestones

  • Computers in the seventies

    • Low cost Si technologies

    • Digital processing

  • The Cellular phone in the 90’s

    • Telecommunication network

    • RF circuits and systems

  • Wireless Sensor Network & RFID in the early 21th century

    • Gate reduction

    • Energy (scavenging, management…)


Context

Wireless Sensor Network Configuration

  • Reduce the node power consumption…

Wireless Sensor Network

B

A

RF link 1

C

RF link 2

…by matching the RF link budget to the communication scenario


OUTLINE

  • Context

  • RF Front End Specifications

  • Circuit design

  • Conclusion & Perspectives


RF Front End Specifications

Node Top-down

  • Node at system level

Memory

RF Link Budget 2

µController

ADC

Sensor

RF Tx/Rx

  • Node Rx at system level

RF Link Budget 1

NFRx2

Power unit

PRx

RFFE

Demodulator

NFRx1

SNRdem

NFRx = PRx - SNRdem+(174-10 log BW)


RF Front End Specifications

RF Link Parameters

BFSK modulation

Channel Characteristic

Attenuation L(R)

PTx

PRx

BER~10-3

distance R

node B

node A

SNRdem~10 dB

BW = 10MHz

NFRx= PRx– SNRdem+ (174-10 log BW)

PRx = PTx - Lpath(R)

2.4 GHz ISM Band


RF Front End Specifications

RFFE and NF specification

  • Node Rx at system level

NFRx2

PRx

RFFE

Demodulator

NFRx1

SNRdem

  • RFFE and system specification

Mixer

LNA

NFRx2

LO

NFRx1

NFRxismainlysupported by the LNA !


RF Front End Specifications

RFFE and NF specification

  • Node Rx at system level

NFRx2

PRx

RFFE

Demodulator

NFRx1

SNRdem

  • RFFE and system specification

Mixer

LNA

NFRx2

LO

NFRx1

NFRxismainlysupported by the LNA !


OUTLINE

  • Context

  • RF Front End Specifications

  • Circuit design

  • Conclusion & Perspectives


Circuit Design

Low Power RF Metric

Optimized biasing!

  • Optimization of RF performances versus power consumption in the transistor…

RF skills

Current consumption

…by maximizing the FOMLP

Vth

~ Vth+ 100mV


Circuit Design

Amplifier Configurations

  • To compensate for the low gm in MI region…

Id

Id

Id

MP

MP

MP

bias

OR

?

RF

RF

RF

out

in

out

out

MN

MN

MN

in

in

Single Transistor Stage (STS)

Self Biased Inverter (SBI)

…active load configurations are preferred!


Circuit Design

Amplifier Configuration

  • Comparison of the Gain BandWidth (GBW) product…

30

Self Biased Inverter (SBI)

20

Gain (dB)

10

Single Transistor Stage (STS)

Frequency (Hz)

0

100G

1G

10G

GBWSTS

…the one of self biased inverter is the largest !

GBWSBI


Circuit Design

LNA topology

LNA 2.4GHz – CMOS 0.13µm

0.8V

VDD

Digital Control

3

VCC

DAC

Id

Cdec

Lpk

50 @ 2.4GHz

Off-chip

M2

Cm2

Rin/buffer

RF

out

50 @ 2.4GHz

M3

Cm3

Lg

Cl

Cm1

in

M1

Rpol2

Rpol1

Vpol2

Vpol1

Currentreuse

with feedback

buffer

LNA core


Circuit Design

Post Layout Performances

S21

NF

900µm

S11

700µm


OUTLINE

  • Context

  • RF Front End Specifications

  • Circuit design

  • Conclusion & Perspectives


Conclusion & Perspectives

System Considerations

  • Match the radio performances with the RF link budget to reduce the power consumption of nodes in WSN

  • A matter of Noise Figure/Gain reconfiguration in the LNA

Requirement

Circuit analysis

  • Best tradeoff between RF skills and current consumption in MI region

  • Select the topology providing the largest GBW

Good

agreement


Conclusion & Perspectives

Done

Next step

NFRx2

NFRx1

Last step

  • A mixer to be designed in MI region

    • Gilbert Cell with current bleeding topology

Mixer

LNA

LO

  • A VCO with low power techniques

    • Negative resistance topology


Thank you for your Attention


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