Mobile Phone hMobile Phone h

H i M thiHeinz MathisHochschule für TecHochschule für TecJanuary 26 2011January 26, 2011

h/w Technologyh/w Technology

chnik Rapperswilchnik Rapperswil

AgendaAgenda

A cellphone is more than jA cellphone is more than j

193 dB of dynamic range!

The receiver architecture o

A somewhat unexpected Aso e at u e pected

just a phonejust a phone

of choice

Apppp

A cellphone is moreA cellphone is moree than just a phonee than just a phone

Signals of differenSignals of differen

GSM tx signal: 2 W 33GSM tx signal: 2 W 33

GSM rx signal (spec. sens

WLAN tx signal: 100mW

GPS rx signal: -130 … -16G S s g a 30 6

nt strengthnt strength

dBmdBm

sitivity level): -102 dBm193 dB

20 dBm193 dB=1019

60 dBm=10

60 d

received power: 1

transmission power: 22 W

10-16 W

GPS received powGPS received pow

~16 dB~16 dB

wer densitywer density

The receiver archiThe receiver archi

Superhet receiverSuperhet receiver

Direct-conversion (zero-IF

Low-IF receiver

itecture of choiceitecture of choice

F) receiver

Challenges of receg

.

.

SeleD i

.

SeleDynamic range

Timing Carrier sync

eiver designg

ectivity Noiseectivity Noise

chronization Channel equalization

History: diode detector and reg

gleichgerichtetRC gefiltert

generative receiver

Superhet (single cop ( g

image filter mixer

ILNA ILNA

local oscillato

nversion))

IF filter

IF amplifierIF output

IF amplifier

or (LO)

Image problem (punImage problem (pun

spectrum|H(f)|

image455 kH455 kHz

455kHz LO

IF 4MHzshort wav

n intended)n intended)

sum of frequencyz

fLO+4MHz

ve radio signal

Superhet (double conversion)

many standard IF bandpass filters availabflicker noise is not an issuegood dynamic range (AGC needed)good dynamic range (AGC needed)

additional components for external filtersadditional components for external filtersimage and spurious signalspower consumption

ble

ss

Direct-conversion receiver (alowpmixer lowpmixer

LOcombas90°

LNAbas90

mixer lowpsimple receiversimple receiverbaseband filtering possibly digital

flicker noiseself-reception causing DC offsetimage-rejection mixer with precisionsecond-order effects

also called zero-IF receiver)pass filterpass filter

I

mplex-valuedseband outputseband output

Qpass filter

Q

Problem with direct-conv

( ) LO l k(a) LO leakage

version receiver: DC

Superhet vs. directpkey property superhet

complexity several stages

filt i t d d IF / tfiltering standard IF / ext.

flicker noise N/A

DC offset N/A

d namic range high AGC neededynamic range high, AGC neede

image needs filtering

power high

precision uncriticalprecision uncritical

t-conversion rxdirect-conversion

simple

ibl di it l i b b d. possibly digital in baseband

depending on technology

self-reception

ed implication on ADC resed implication on ADC res.

= signal

medium

high precision neededhigh precision needed

Direct-conversion recect co e s o ec(no image problem, bu

spectrumspectrum|H(f)|

zero-IF=DC RFLO

eiver:e eut DC problem)

sum of frequency

ffLO+RF=2RF

Low-IF receiver(no DC problem, but a

spectrum|H(f)||H(f)|

IF

lo IF RLOlow-IF RLO

again image problem)

sum of frequencyq y

fRF LO+RF=~2RFRF LO+RF=~2RF

Low-IF receiver:( DC bl b t

spectrum

(no DC problem, but agaspectrum

|H(f)| strong adjacent cha

IF

RFLOlow-IF RFLO

We need a complex basWe need a complex basADC with a high dyna

i i bl )ain image problem)

annel

sum of frequencysum of frequency

fF LO+RF 2RFF LO+RF=~2RF

seband filter or anseband filter or an amic range!

Low-IF receivers

Cellular handset mmanufacturers

GSM handset archGSM handset arch

ADC voicecodec

encry-ption

block coder

inle

microphone

i d bl k dDAC voice

codecdecry-ption

block decoder

dle

loudspeaker

hitectureshitectures

nter-eaver

burst comp.

conv coder

modu-lator

d i t b tViterbi d ddeinter-eaver

burstdecomp

Viterbialgorithm

demodu-lator

The two major conThe two major con

Power consumption staPower consumption sta

Complexity price, size

ncerns:ncerns:

and by timeand-by time

Siemens S35 (superhet)

Siemens S35 (superhet)

Nokia 3300 (directNokia 3300 (direct-conversion rx)conversion rx)

Apple‘s iPhone 3GApple s iPhone 3GGG

The “GPS” solutioThe GPS solutioGPS t iGPS antenna size

on of the iPhoneon of the iPhone

normal size

How does the iPhone

BTS database

WLAN database

e get its position?

+

WLAN Access Point

A somewhat unexA somewhat unexLCR-Meter for theLCR Meter for the

|Z

xpected App: Anxpected App: An e iPhonee iPhone

Z(f)|

R L CR L C

f