Microwave CMOS Beamforming Transmitters

Abstract

The increase of the consumer electronics market the last couple of decades has been

one of the main drivers of IC process technology development. The majority of the

ICs are used in digital applications, and for these CMOS is the choice of technology.

The urge to squeeze more transistors on to a given area has led to shrinking feature

sizes. It has resulted in higher transition frequencies and reduced supply voltage.

During the last decade the increasing transition frequency has enabled CMOS to be

used in RF applications, as well. Unfortunately, the decreasing supply voltage that,

until recently, has accompanied the reduced feature sizes makes it more difficult to

build power amplifiers that can deliver the amount of power needed to transmit the

radio signal over the desired distance. In the receiver, the reduced supply voltage has

resulted in reduced signal swing, which compromises linearity and dynamic range.

In this thesis new topologies for the power amplifier is investigated, and the approach

to combine the power from multiple power amplifiers is taken. In this way,

despite the low supply voltage, the transmitted power by the IC can still be high. The

increased transition frequency of CMOS technology can be used to increase the operating

frequency to tens of GHz. The possibility for small sized phased antenna arrays

then reveals, giving high directivity of the antenna and the potential for electrical beam

steering. This both reduces interference to nearby receivers through spatial selectivity,

and increases the equivalent isotropic radiated power. Power amplifiers with digital

360◦ phase control and antenna arrays have been investigated.

In recent years applications at high operating frequencies have attained much focus

from both academia and industry, such as automotive radar at 77 GHz andWLAN

at 60 GHz. Even though the shrinking feature sizes of CMOS transistors have resulted

in transit frequencies above 150 GHz, the high frequency required by many applications

is still a great challenge for the CMOS designer. Therefore, in Paper IV and

Paper VI different approaches to keep the on chip frequency lower than the RF carrier

frequency as long as possible have been taken. In Paper IV two different frequency

doubling 60 GHz power amplifier topologies are presented, and in Paper VI a subharmonic

mixer with 30 GHz radio frequency and 15 GHz differential local oscillator is

presented.

Many transceiver architectures rely on quadrature signals driving the down- or upconversion

mixers. The power amplifiers in Paper I and II need quadrature signals

to implement the digital phase control. Therefore, in Paper V a three-stage active

polyphase filter with quadrature output signals, high operation frequency, and wide

bandwidth is analyzed. Analytical equations for both voltage gain and phase transfer

function of a loaded stage are derived. The filter shows robustness against process

parameter spread and achieves high quadrature signal quality from 6 GHz to 14 GHz.

• author: Wernehag, Johan
• supervisor: Henrik Sjöland
• opponent: Associate Professor Klumperink, Eric, University of Twente, Department of Electrical Engineering
• organization: Department of Electrical and Information Technology; Elektronikkonstruktion-lup-obsolete (research group); Analog RF-lup-obsolete (research group)
• publishing date: 2008
• type: Thesis
• publication status: published
• subject: Electrical Engineering, Electronic Engineering, Information Engineering
• keywords: Beamforming transmitter, CMOS, frequency doubling power amplifier, polyphase filter, phase shifting
• in: Department of Electrical and Information Technology, Series of licentiate and doctoral theses
• volume: 12
• pages: 234 pages
• defense location: Lecture Hall E:1406, E-building, John Ericssons väg 4, Lund University, Faculty of Engineering, LTH
• defense date: 2008-12-12 10:15:00
• ISSN: 1654-790X
• language: English
• LU publication?: yes
• id: 2122dca9-b20e-4f1b-8819-e7ffb39bebf6 (old id 1265511)
• date added to LUP: 2016-04-01 14:08:37
• date last changed: 2019-05-21 12:58:29