Design, Modeling and Experimental Characterisation of RF and Microwave Devices and Subsystems

WPR3 ICC-06 NEWCOM workshop - June 11th, 2006

Design, Modeling and ExperimentalCharacterisation of RF and Microwave Devices andSubsystems

Presented by: Abdullah Atalar


OUTLINE

Three areas of Interest Power amplifier nonlinearity and its effects on

system performance Using Real Frequency Technique for

wideband matching of RF components Integration of RF IC Front-ends


Power amplifier Nonlinearity and its effects on system performance

Chalmers University: Ali Behrevan, Thomas Eriksson

Bilkent University: Mustafa Durukal, Hakan Arslan, Gul Safak, Abdulllah Atalar, Tarik Reyhan

Polytechnik Torino: Daniel Bustos, Simona Donati, Marco Pirola, Giovanni Ghione


A typical wireless transmitter


Digital baseband predistortion


it++ simulation diagram


Nonlinearity model

AM/AM and AM/PM models Soft Limiter, RAPP, Saleh, Ghorbani, Rapp

and Arctan models Arctan model:

)(2211 )))(arctan())(arctan(()( txjetxtxty

x(t) complex envelope of input, y(t) complex envelope of output.


Power Amplifier TypesSOFT LIMITER


Power Amplifier TypesRAPP


Power Amplifier Types3rd Order Polynomial


Power Amplifier TypesSALEH (AM/AM)


Power Amplifier TypesSALEH (AM/PM)


New amplifier class in it++

Implements nonlinearity models

Needs four parameters to represent nonlinearity: Two complex, two real.

Parameters are found by curve fitting to measured characteristics.




A new predistorter class in it++


Update algorithm

During the training sequence for every input symbol, the coefficients of the polynomial predistorter are updated according to LMS algorithm using amplitude and phase errors.


Simulation #1: No Band Pass Filter

Output of raised cosine filter After power amplifierAfter predistorter


Simulation #2: With Band Pass Filter

Output of raised cosine filter After power amplifierAfter predistorter +BPF


Baseband Model of a Communication System that uses OFDM


Two Sources of Distortion In The Received Signal

Additive noise channel between the transmitter and receiver sides

Nonlinearity of the power amplifier at the end of the transmitter side


Effect of Noise on the System Performance


Effect of Noise on the System Performance

Figure of merit: Bit Error Rate (BER)

Error rate in a 16-QAM OFDM system with no amplification

SNR (signal to noise ratio) limits the BER of the system

To reduce the effect –>use Convolutional Encoder


Effect of Nonlinear Power Amplifier on the Transmitted Signal

In-

bandOuter-

bandOuter-band


Base-band Model of a Three Transmitter – Receiver System


Distortions Introduced by the Nonlinear Power Amplifier

In a single transmitter – receiver system In-band distortion

In a multiple transmitter – receiver system In-band distortion Outer-band distortion




Outer-band distortions overlap with and are added to the in-band distortions

Results in degradation in the BER performance

The amount of degradation depends on Degree of the nonlinearitySpacing between adjacent channels (Δf)



Degree of Nonlinearity (in simulations) identified by the amplifier parameter IBO (input

backoff)

How far the input is from the saturation region

IBO


Inputs of the Program

Number of transmitted bitsEncoder typeBase-band modulatorNumber of carriers in OFDMOversampling factorPower amplifier type IBO (input back-off)SNR (signal to noise ratio)Channel spacing


Graphical Interface for Link Simulator


In All Simulations

Total number of bits = 106

No coding 16 – QAM OFDM Number of carriers = 1024 Oversampling factor = 16


Other Inputs For each amplifier type simulations are done

for the following parameters:

IBO (in dB): integer from 0 to 6SNR (in dB): integer from 0 to 20Channel spacing ÷ 2W = 1 : 0.2 : 3

W is the channel bandwidth of the transmitted signal


Simulation Results


Simulation Results


Simulation Results


Using Real Frequency Technique for wideband matching of RF components

Istanbul University: M. Sengul, S. Yarman

Techical University of Ilmenau: J. Trabert, Kurt Blau, Matthias Hein, C. Hartmann, J. Weber

Uppsala University: Peter Lindberg, Eric Ojefors, Anders Rydberg


Real Frequency Technique

An analytical method of matching network design

Applicable to components with measured data


Final front-end matching network (top) and back-end matching network (bottom).

17GHz-23 GHz RF SWITCH


(IEEE ISCAS 2006, Kos, Greece, May 21-24, 2006)Transducer power gain of the matched switch


Matching Network Design for a Dual Band PIFA Antenna

Layout of antenna


The main challenge in terminal antenna design for cellular applications is, due to the limited available volume, obtaining sufficient bandwidth, at multiple frequency bands, without loss of radiation efficiency.



A complex matching network synthesized using the simplified real frequency technique, to study the real achievable bandwidth of a dual band PIFA antenna.



Double Band PIFA Antenna Matching Network

CAP

C=ID=

1.162 pFC1

CAP

C=ID=

1.075 pFC2

CAP

C=ID=

1.237 pFC3

IND

L=ID=

7.925 nHL1

IND

L=ID=

19.57 nHL2

IND

L=ID=

21.06 nHL3

IND

L=ID=

8.027 nHL4

1

SUBCKT

NET=ID=

"DB_PIFA900_1800" S1 PORT

Z=P=

50 Ohm1

Final matching network


Double Band Antenna824-960 and 1710-1990 MHz


Measured Results


Joint article submitted to EuCAP 2006.

Simulated and measured results indicatethe possibility of extending the useableoperating frequency band of a GSM900/1800antenna to quad band coverage, i.e.GSM850/900/1800/1900.



ApproachApproach IInvestigate port-isolations and their impedancesnvestigate port-isolations and their impedances Optimize radiating elements and port parametersOptimize radiating elements and port parameters Optimize beam forming and bandwidthOptimize beam forming and bandwidth

(superdirective feed)(superdirective feed) Final design of antenna array andFinal design of antenna array and

decoupling networkdecoupling network

(e.g. hybrid-integrated module)(e.g. hybrid-integrated module) Decoupling, matching and beam forming network

port 1 port 2 port n

Other possible applications for Real Other possible applications for Real Frequency TechniqueFrequency Technique


Integration of RF IC Front-ends

University of Pisa: D. Zito, B. Zeri, L. Fanucci

Technical University of Ilmenau: Kurt Blau, Matthias Hein

Uppsala University: Peter Lindberg, Eric Ojefors, Anders Rydberg


TX/RX Antenna Switch

Image Reject Filter

LNA

De

mo

dula

to

r

PA

f0

Mo

du

lat

or

Single Silicon Die

RX

TX

Typical RF Front-end


Dem

odulato

r

PA

Modulato

r

Single Silicon Die

RX

TX

f0

LNA

Ant

enna

Sw

it ch

Desired RF Front-end


RX

TX

Off-chip

Limited ZOFF /ZON

(Q-factor integrated inductors)

Insertion Loss ≈1-2 dB

TX/RX Antenna Switch State-of-Art


fehje

eqL

bI

bV

,b bI V ,fe b bh I V

The BSI circuit can be exploited to implement high quality factor LC active filters

f0

1,

20 b b

eq

f I VL C

, 0 eqb b

eq

LQ I V

R

35< Q <120 in the range of 5.15< f0< 5.835

The Boot-Strapped Inductor (BSI)


Switching Mode (ON/OFF) Biasing (IB1, VB2)

Low/High Impedance (ZIN) High state if CA is ON Low state if CA is OFF

If inserted between antenna, receiver and transmitter, the BSI can be exploited to isolate T/R channels

Boot-Strapped Inductor (BSI): “Switching mode”


Patented

Time Division Duplexing

Different linearity constrains (R/T)

Receive Time Interval (RX)

CA OFF in Receiver

CA ON in Transmitter

Transmit Time Interval (TX)

CA ON in Receiver

CA OFF in Transmitter

Not de-embedded from LNA/PA

TX/RX Antenna Switch based on BSI


TX/RX Antenna Switch: Chip (1/2)


Microstrip Test Board

TX/RX Antenna Switch: Chip (1/2)


Insertion Loss (IL) vs. Power available from the source in R and T mode

Performance

ILR < 0.236 dBILT < 1.1 dB

< 2 dB

Specifications (typical IL)

TX/RX Antenna Switch: Performance vs. Specifications


The feasibility of a Fully Integrated Antenna Switch on standard silicon technology has been demonstrated and Patented

The main performances are beyond within the requirements of several Wireless LAN standards (ILRmax = 0.235 dB, ILTmax = 1.1 dB, @ 5-6 GHz)

“Silver Leaf” at IEEE Conf. PRIME 2005 (EPFL, Lausanne)

“First Price” (10KEuro) at NEWCom Idea Competition “M.Boella” (I3P, Torino)

TX/RX Antenna Switch : Conclusions

Documents

Design, Modeling and Experimental Characterisation of RF and Microwave Devices and Subsystems