reconfigurable ultra low power lna for 2.4ghz wireless sensor networks tarist., mabrouki a.,...

Reconfigurable Ultra Low Power LNA for

2.4GHz Wireless Sensor Networks

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

Bordeaux, France

http://www.ims-bordeaux.eu/


2ICECS 2010 – 13-15 Décembre – Athens, Greece

Context

RF Front End Specifications

Circuit design

Conclusion & Perspectives

OUTLINE



Context


Circuit design


OUTLINE



Context

MicroElectronic Milestones

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

…by matching the RF link budget to the communication scenario

Reduce the node power consumption…

RF link 1

RF link 2

AB

C

Wireless Sensor Network



Context


Circuit design


OUTLINE




Node Top-down

Node at system level

RF Tx/Rx

Power unit

µController ADC Sensor

Memory

RF Link Budget 1

RF Link Budget 2

RFFE Demodulator

Node Rx at system level

NFRx1

NFRx2

PRx

SNRdem

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




RF Link Parameters

NFRx = PRx – SNRdem + (174-10 log BW)

PRxPTx

node A node B distance R

PRx = PTx - Lpath(R)

Attenuation L(R)BFSK modulation

BER~10-3

SNRdem~10 dB

Channel Characteristic

2.4 GHz ISM Band

BW = 10MHz

R NFRx PRx Lpath(dB)

10 m 26 dB -83 dBm 90 dB

20 m 13 dB -95 dBm 102 dB

30 m 7 dB -102 dBm 109 dB




RFFE and NF specification

RFFE Demodulator


NFRx1

NFRx2

PRx

SNRdem

RFFE and system specification

LNANLNA

N

LNA

mixerLNARx F

GG

F

G

FFF

1...

1...

1

NFRx is mainly supported by the LNA !

LNA

LO

Mixer

NFRx1

NFRx2




RFFE and NF specification

RFFE Demodulator


NFRx1

NFRx2

PRx

SNRdem

RFFE and system specification

NFRx is mainly supported by the LNA !

LNA

LO

Mixer

NFRx1

NFRx2

R NFLNA GLNA NFmixer

10 m 25 dB 5 dB 18 dB

20 m 11 dB 10 dB 18 dB

30 m 4.5 dB 14 dB 18 dB



Context


Circuit design


OUTLINE



Circuit Design

Low Power RF Metric

DC

TmLP I

fgFOM

.

0.00E+00

5.00E+10

1.00E+11

1.50E+11

2.00E+11

2.50E+11

3.00E+11

3.50E+11

VGS (V)

FO

ML

PModerate inversion

Strong In-version

WeakInversion

Vth ~ Vth + 100mV…by maximizing the FOMLP

Optimization of RF performances versus

power consumption in the transistor…

RF skills

Current consumption

Optimized biasing!



Circuit Design

Amplifier Configurations

…active load configurations are preferred!

To compensate for the low gm in MI region…

bias

in

outRF

MN

MP

Id

in

outRF

MN

MP

Id

outRFin

MN

MP

Id

Single Transistor Stage (STS)

Self Biased Inverter (SBI)

OR ?



Circuit Design

…the one of self biased inverter is the largest !

Single Transistor Stage (STS)

Gai

n (d

B)

10G0

10

20

30

1GFrequency (Hz)

100G

Self Biased Inverter (SBI)

Comparison of the Gain BandWidth (GBW) product…

GBWSTS

GBWSBI

Amplifier Configuration



Circuit Design

LNA topology

LNA 2.4GHz – CMOS 0.13µm

RF

in M1

M2

Id

Vpol1

Rpol1

Cl

VDD

Lg Cm1

Vpol2

Rpol2

M3

Cm2

Cm3

Lpk

out

VCC

Rin/buffer

DAC3

0.8V

Cdec

Current reuse

with feedback buffer

Digital Control

50 @ 2.4GHz

50 @ 2.4GHz

LNA core

Off-chip



Circuit Design

Post Layout Performances

0

2

4

6

8

10

12

14

1 1,5 2 2,5 3 3,5 4

S21

(dB)

f (GHz)

VCC=300mVVCC=400mVVCC=600mV

-18

-16

-14

-12

-10

-8

-6

-4

-2

01 1,5 2 2,5 3 3,5 4

S11

(dB)

f (GHz)


0

2

4

6

8

10

12

14

1 1,5 2 2,5 3 3,5 4

NF

(dB)

f (GHz)


INOUT

VCC

Cdec

S21

S11

NF

900µm

700µm



Context


Circuit design


OUTLINE




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

Best tradeoff between RF skills and current consumption in MI

region

Select the topology providing the largest GBW

System Considerations

Circuit analysis

R NFLNA GLNA

10 m 25 dB 5 dB

20 m 11 dB 10 dB

30 m 4.5 dB 14 dB

Pdc NFLNA GLNA

60 µW 4.4 dB 12.2 dB

90 µW 4 dB 13.1 dB

120 µW 3.8 dB 14.6 dB

Requirem

ent

Good

agreement




Done Next step

LNA

LO

Mixer

NFRx1

NFRx2

A mixer to be designed in MI region

Gilbert Cell with current bleeding topology

A VCO with low power techniques

Negative resistance topology

Pdc NFmixer Gmixer

200 µW 18 dB 5-8 dB

Last step

Pdc PN@10MHz Frequency

100 µW -80 dBc/Hz 2.4 GHz



Thank you for your Attention


reconfigurable ultra low power lna for 2.4ghz wireless sensor networks tarist., mabrouki a.,...

Documents