Abstract:
Nowadays, wireless communications are playing an important role in everydays life of the people everywhere
around the world. Due to the emerging convergence of information and communications technologies, the
customers of the telecommunication service providers are able to access to various information and media
everywhere. From the technological point of view, broadband data transfer e.g. transfer of internet, sound and
video contents via mobile communication systems requires higher data transfer rate. So, mobile and wireless
communication technologies are required to be constantly improved in order to cope with the higher data rate.
New standards of wireless communications to be licensed for services in Thailand are 3G WCDMA and
WiMAX which offer significantly higher data rate compared to the yet widespread GSM. However, standards
with higher data rates use complex signals with non constant signal envelope modulation which leads to
challenges for design engineers of communication systems. One of the most important parts of wireless
communication systems is RF power amplifiers. The performance of power amplifiers has a significant
influence on the entire system performance. In case that the amplifier performance increases, then, the entire
system performance increases also significantly. RF power amplifiers are complex active circuits. During the
design process, several aspects including power gain, linearity, noise, efficiency and stability must be taken into
account. Moreover the design process requires know-how in several areas including device characterization and
modeling; computer aided circuit design as well as RF measurement techniques. Currently, Thailand is still in a
lack of human resource with the expertise in this research field. As a consequence, Thai communication
industry is dependent on foreign technologies to a large extent which leads to an unnecessarily high investment
costs of communication services. In this project, the researchers will design and prototype a class AB RF power
amplifier for wireless communications which is widely used in wireless communication base stations and
repeaters. The frequency range is between 200 and 900 or 1800 and 2450 MHz. The RF output power is 2-5
Watt. The power devices of the amplifier prototype are LDMOS FETs or HFET. In case of success, the
prototype would be the first of its kind built in Thailand by Thai researchers in a Thai university. Such
achievement would be an important step for the first excellent center for RF active circuits in Thailand.