Class-E Power Amplifiers for Pulsed Transmitters
Licentiatavhandling, 2012

Nowadays the main driving parameters for the radio transmitter research are: energy efficiency, frequency re-configurability and integration. Pulsed transmitter architectures have attracted large interest in the recent years due to their potential to meet these demands. In pulsed transmitters, a highly efficient switch mode power amplifier (SMPA) is used in conjunction with a pulse modulator to achieve high efficiency linear amplification. Digital implementation of the modulator enables wide bandwidth for the signal generation path and improves the level integration. The bandwidth in a pulsed transmitter is however typically limited by the load matching network of the SMPA. This thesis presents two main contributions in the field of pulsed transmitter architectures. In the first part focus is given to bandwidth improvement of class-E switch mode PAs. A continuum of novel closed-form class-E modes is derived extending the traditional class-E design space. The extended design space provides important possibilities for wide band design of the class-E load networks and for further efficiency optimization of class-E PAs. A wide band design methodology is thus developed based on the analytical design equations. In the second part, focus is given to efficiency improvement of RF pulse width modulation (RF-PWM) based transmitters. A new SMPA topology particularly suitable for energy efficient amplification of RF-PWM signals is derived. It is analytically shown that high efficiency can be maintained over a wide power dynamic range if the imaginary part of the class-E load impedance is varied along with the pulse width. Using in-house (Chalmers University) SiC varactor diodes to implement the tunable load impedance, a 2 GHz 10 W peak output power CMOS-GaN HEMT RF-PWM transmitter demonstrator is realized. The static measurements show that a drain efficiency >70% can be obtained over a 6.5 dB dynamic range. A digital pre-distortion based linearization scheme is proposed to enhance the linearity of the transmitter. An adjacent power ratio of -45 dBc and average drain efficiency of 67% is achieved using a realistic W-CDMA communication signal. These results clearly demonstrate the feasibility of the proposed pulsed transmitter topology for high efficiency linear amplification.

RF-PWM

pulsed transmitters

frequency agility

energy efficiency

Class-E

MC2 Fasrummet A820
Opponent: Lars bengtsson

Författare

MUSTAFA ÖZEN

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

High efficiency RF pulse width modulation with tunable load network class-E PA

2011 IEEE 12th Annual Wireless and Microwave Technology Conference, WAMICON 2011,; (2011)

Paper i proceeding

Styrkeområden

Informations- och kommunikationsteknik

Ämneskategorier

Annan elektroteknik och elektronik

Technical report MC2 - Department of Microtechnology and Nanoscience, Chalmers University of Technology

MC2 Fasrummet A820

Opponent: Lars bengtsson