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A MEMS-based reconfigurable RF receiver front-end utilizing multi-port technology [Elektronische Ressource] / by Torsten Mack

183 pages
A MEMS-Based Reconfigurable RF ReceiverFront-End Utilizing Multi-Port TechnologyA Thesis Submitted to theTechnical Faculty of theUniversity of Erlangen-NurembergIn Partial Fulfillmentof the Requirements for the DegreeDOKTOR-INGENIEURbyTorsten MackErlangen 2005Rekonfigurierbarer Hochfrequenz-Empf¨angermit Mikro-Elektromechanischen Systemenauf Basis von Multi-Tor-TechnologieDer Technischen Fakulta¨t derUniversita¨t Erlangen-Nu¨rnbergzur Erlangung des GradesDOKTOR-INGENIEURvorgelegt vonTorsten MackErlangen 2005Als Dissertation genehmigt vonder Technischen Fakultat der¨Friedrich-Alexander Universita¨t Erlangen-Nu¨rnbergTag der Einreichung: 15. Juni 2005Tag der Promotion: 11. August 2005Dekan: Prof. Dr. Albrecht WinnackerBerichterstatter: Prof. Dr.-Ing. Dr.-Ing. habil. Robert WeigelProf. Dr.-Ing. Franz X. Kartner (MIT)¨AcknowledgementsThis work was conducted at the DaimlerChrysler Research Facility in Ulm, Germany,Department of Vehicle Sensing and Communications Microwave, and at the Massa-chusetts Institute of Technology in Cambridge, MA, USA, between November 2001and March 2005.I would like to thank Prof. Robert Weigel from the Friedrich-Alexander-UniversityErlangen-Nuremberg, Chair of Technical Electronics, and Prof. Franz K¨artner fromMassachusetts Institute of Technology, Research Laboratory of Electronics for theirinvolvement and the supervision of this work.I would especially like to thank Prof.
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A MEMS-Based Reconfigurable RF Receiver
Front-End Utilizing Multi-Port Technology
A Thesis Submitted to the
Technical Faculty of the
University of Erlangen-Nuremberg
In Partial Fulfillment
of the Requirements for the Degree
DOKTOR-INGENIEUR
by
Torsten Mack
Erlangen 2005Rekonfigurierbarer Hochfrequenz-Empf¨anger
mit Mikro-Elektromechanischen Systemen
auf Basis von Multi-Tor-Technologie
Der Technischen Fakulta¨t der
Universita¨t Erlangen-Nu¨rnberg
zur Erlangung des Grades
DOKTOR-INGENIEUR
vorgelegt von
Torsten Mack
Erlangen 2005Als Dissertation genehmigt von
der Technischen Fakultat der¨
Friedrich-Alexander Universita¨t Erlangen-Nu¨rnberg
Tag der Einreichung: 15. Juni 2005
Tag der Promotion: 11. August 2005
Dekan: Prof. Dr. Albrecht Winnacker
Berichterstatter: Prof. Dr.-Ing. Dr.-Ing. habil. Robert Weigel
Prof. Dr.-Ing. Franz X. Kartner (MIT)¨Acknowledgements
This work was conducted at the DaimlerChrysler Research Facility in Ulm, Germany,
Department of Vehicle Sensing and Communications Microwave, and at the Massa-
chusetts Institute of Technology in Cambridge, MA, USA, between November 2001
and March 2005.
I would like to thank Prof. Robert Weigel from the Friedrich-Alexander-University
Erlangen-Nuremberg, Chair of Technical Electronics, and Prof. Franz K¨artner from
Massachusetts Institute of Technology, Research Laboratory of Electronics for their
involvement and the supervision of this work.
I would especially like to thank Prof. Franz K¨artner for embracing me as a member of
his research group during my research period in the United States.
I would like to gratefully acknowledge the enthusiastic supervision of Dr. Johann-
Friedrich Luy from DaimlerChrysler Research and Technology. His knowledge and
expertise helped guide me through this work.
I want to sincerely thank Dr. Bernd Schauwecker and Dr. Karl Strohm for numerous
discussions and countless hours of technical support during the design phase and fab-
rication of the MEMS.
I want to thank Dietrich Eisbrenner for his generosity in taking the extra time in the
clean-room and assisting me during the fabrication process of the MEMS.
Many thanks to Dr. Thomas Mu¨ller for his inspiration in the field of SDR and for
helping the thesis take shape and progress forward.
Many thanks also to Thomas Eireiner and Dr. Konrad B¨ohm for their intellectual
support and for the various fruitful discussions that were essential for the success of
this work.
Furthermore, I want to thankWinfried Simon fromIMSTGmbH and Dr. JanMehner
from FEMWARE GmbH for supporting the development process of the MEMS with
their simulations.
Thanks also to FrancoisDeborgies and Laurent Marchand fromESA for their support
and suggestions in the development of the MEMS.
Many thanks to all my interns and Master Thesis students, especially to Alexander
Honold.
Lastbutnotleast,Iwouldliketothankmyparents,IngeandEugen,andmygirlfriend
Annie Seapan. Without their encouragement and support, this work would not have
been possible. Many thanks also to my sincere friends Micky, Andrea, and Annie for
making me dinner and proofreading this thesis.Abstract
The aim of this work is thedesign and evaluation ofa reconfigurable, universal, multi-
band, multi-standard receiver front-end. This front-end is based on software defined
radio (SDR) which leads to a significant reduction of hardware circuit complexity.
For down conversion, the multi-port receiver principle has been chosen as it is a very
promising candidate to cope with the largefrequency ranges needed for receiving mul-
tiple standards.
Theoriginalmulti-port(orsix-port)theoryappliesonlytoalternativenetworkanalyz-
ers. Since the late 1990s, the six-port principle has also been used for radio frequency
(RF) communications receivers, but the principle of the frequency conversion process
was never thoroughly described. Therefore, an accurate mathematical description of
the frequency conversion and demodulation processes in multi-port receivers needs to
become established. With this detailed understanding of the multi-port theory, the
six-port receiver can then be evaluated and its performance can be compared to that
of conventional architectures.
To integrate present and future frequency bands from 1 GHz through 40 GHz into
a single receiver, the hardware of the multi-port interferometer itself needs to be re-
configurable. Hardware reconfigurability in the analog front-end necessitates multi-
ple routing structures, i.e. receive/ transmit (RX/TX) switches or front-end selector
switches. Itisobviousthattheseswitchesmusthaveaverylowlosssoasnottodegrade
the signal-to-noise (SNR) ratio. On the other hand, RX/TX switches must support
very high powers. As we will see, these two requirements, namely low loss and high
power, cannotbeachieved sufficiently with conventional PINdiodeswitches. Thenew
and upcoming micro-electromechanical systems (MEMS) technology offers an elegant
way to accomplish these specifications. As low loss, high power switches are the key
element for future multi-band multi-standard transceivers, much effort has been put
in the design, simulation, fabrication, and evaluation of new suitable radio frequency
(RF) MEMS switches – in particular, a single pole double throw (SPDT) switch. RF
MEMS switches designed with this new technology can cover a frequency range from
DCto40GHzwithaninsertionlossbelow1dBandcanhandleseveralwattsofpower.
When the performance of the new MEMS switches is known, they can be applied and
evaluated in the context of the six-port receiver. For an accurate evaluation of the
reconfigurablesix-portinterferometer, S-parametermeasurements needtobeanalyzed
in respect to signal attenuation and phase relations. A detailed analysis of these pa-
rameters will further improve the understanding of the multi-port principle, especially
the requirements for covering a large frequency range.In the context of communications the meaningful physical entity is the symbol er-
ror rate. The multi-band, multi-standard six-port receiver front-end must meet the
requirements of today’s communication standards. This implies a good noise per-
formance which can be characterized by the symbol error rate of the demodulated
symbols with respect to the bit energy over noise (E /N ) ratio.b 0Contents
1 Introduction 1
1.1 Motivation and State of the Art Technology . . . . . . . . . . . . . . . 1
1.2 Contribution and Outline . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Theoretical Background of Multi-Port Receivers 5
2.1 The Software Defined Radio Concept . . . . . . . . . . . . . . . . . . . 5
2.1.1 Introduction to Software Defined Radio . . . . . . . . . . . . . . 5
2.1.2 Software Defined Radio Architectures . . . . . . . . . . . . . . . 6
2.2 The Theory of Diode Detectors . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Semiconductor Diode Circuit Model . . . . . . . . . . . . . . . . 9
2.2.2 Diode Detectors in Multi-Port Applications . . . . . . . . . . . 10
2.3 Simple Description of Multi-Port Receivers . . . . . . . . . . . . . . . . 12
2.4 Mathematical Description of the Multi-Port Receiver . . . . . . . . . . 13
2.4.1 Theory of Additive Mixing . . . . . . . . . . . . . . . . . . . . . 13
2.4.2 The Multi-Port Theory . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.3 Calibration Method and IQ Calculation . . . . . . . . . . . . . . 17
2.5 Frequency Conversion in Multi-Port Receivers . . . . . . . . . . . . . . 18
3 RF MEMS For Signal Routing 25
3.1 Motivation and Introduction to RF MEMS . . . . . . . . . . . . . . . . 25
3.1.1 Typical Applications of RF MEMS . . . . . . . . . . . . . . . . 27
3.2 Overview of the RF MEMS Under Investigation . . . . . . . . . . . . . 28
3.3 Theoretical Background of the Simulations . . . . . . . . . . . . . . . . 30
3.3.1 Mechanical Domain Simulations . . . . . . . . . . . . . . . . . . 30
3.3.2 Electrostatic Domain Simulations . . . . . . . . . . . . . . . . . 32
3.3.3 Fluid Domain and Transient Response Simulations . . . . . . . 33
3.3.4 Electromagnetic Domain Simulations . . . . . . . . . . . . . . . 34
3.4 Design, Layout, and Simulation Results . . . . . . . . . . . . . . . . . . 35
3.4.1 Shunt Airbridge Switch . . . . . . . . . . . . . . . . . . . . . . . 36
3.4.2 Toggle Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.4.3 Single Pole Double Throw (SPDT) Switch . . . . . . . . . . . . 46
3.4.4 RF Cross . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.5 Process Flow and Fabrication . . . . . . . . . . . . . . . . . . . . . . . 49
3.6 SEM Micrographs and Experimental RF Measurement Results . . . . . 52
iContents
3.6.1 Experimental Results of the Shunt Airbridge Switch . . . . . . . 52
3.6.2 Experimental Results of the Toggle Switch . . . . . . . . . . . . 54
3.6.3 Experimental Results of the SPDT Switch . . . . . . . . . . . . 56
3.6.4 Experimental Results of the RF Cross . . . . . . . . . . . . . . 59
3.7 Additional Measurements and Reliability Results . . . . . . . . . . . . 60
3.7.1 Switching Time Measurement Results . . . . . . . . . . . . . . . 61
3.7.2 RF Power Measurement . . . . . . . . . . . . . . . . . . . . . . 63
3.7.3 Switch Cycle Measurement Results . . . . . . . . . . . . . . . . 65
3.7.4 DC Contact Resistance . . . . . . . . . . . . . . . . . . . . . . . 66
3.7.5 Temperature Dependency and Reliability . . . . . . . . . . . . . 67
4 The MEMS-Based Multi-Band Six-Port Circuit 69
4.1 Introduction to Passive RF Multi-Port Interferometers . . . . . . . . . 69
4.2 Options for the Multi-Port Architecture . . . . . . . . . . . . . . . . . 70
4.2.1 The N-Port Interferometer . . . . . . . . . . . . . . . . . . . . . 70
4.2.2 Five-Port and Six-Port Interferometers . . . . . . . . . . . . . . 71
4.3 Design and Analysis of a 1.5 GHz Six-Port Interferometer (SP1500) . . 73
4.3.1 Theoretical Background of the Electromagnetic Simulations . . 74
4.3.2 Substrate and Microstrip Lines . . . . . . . . . . . . . . . . . . 74
4.3.3 Design and Simulation Results of the Power Divider . . . . . . . 76
4.3.4 Design and Simulation Results of the Quadrature Hybrid . . . . 77
4.3.5 Simulation and Measurement Results of SP1500 . . . . . . . . . 79
4.4 Analysis of the 2 GHz to 25 GHz Six-Port Interferometer (SP40) . . . . 85
4.4.1 Guidelines for Broadband Power Divider Design . . . . . . . . . 86
4.4.2 Measurement Results of a Broadband Power Divider . . . . . . 86
4.4.3 Guidelines for Broadband Quadrature Hybrid Design . . . . . . 87
4.4.4 Measurement Results of a Broadband Quadrature Hybrid . . . . 87
4.4.5 Measurement Results of the SP40 . . . . . . . . . . . . . . . . . 88
4.5 The Reconfigurable MEMS-Based Multi-Band Front-End . . . . . . . . 91
4.5.1 Targeted Applications of RF MEMS in Receiver Front-Ends . . 91
4.5.2 The MEMS-Based Reconfigurable Six-Port Front-End . . . . . . 93
4.5.3 Results of the MEMS-Based Reconfigurable Six-Port Front-End 94
4.5.4 The RF MEMS SPDT Antenna Switch . . . . . . . . . . . . . . 101
5 Performance of the Multi-Band Six-Port Receiver 103
5.1 Simulation Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5.1.1 Functional Principle of the Simulation Program CppSim . . . . 103
5.1.2 Simulation Set Up . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.1.3 Simulation Run . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.2 Simulation of the Six-Port Receiver . . . . . . . . . . . . . . . . . . . . 109
5.2.1 Influence of Channel Noise . . . . . . . . . . . . . . . . . . . . . 109
5.2.2 Frequency Offset and Phase Noise Dependency. . . . . . . . . . 112
5.3 Characterization of the Schottky Diode Detectors . . . . . . . . . . . . 113
5.4 Measurement Results of the Multi-Band Six-port Receiver . . . . . . . 115
ii