Helias Koulouzis

Distortion correction of LDMOS power amplifiers using hybrid RF second harmonic injection/digital predistortion linearization

An LDMOS RF power amplifier for RF multichannel wireless systems with improved IMD performance characteristics is presented. The application of two combined linearization methods is being tested with the help of circuit simulation software ADS. The injection of the fundamental signals second harmonic in the RF amplifier, as well as a digital predistortion technique, is combined in order to achieve IMD improvement. By proper selection of phase and amplitude of the injected second harmonic signal, it is possible to reduce IMD products that have already been reduced by the well established method of digital predistortion

LDMOS Power Amplifiers with CRLH Combiners for LINC Transmitters

An outphasing system at 2.14 GHz using LDMOS power amplifiers with an attempt to use composite right/left handed material transmission (CRLH) lines in the combiner part is presented. Linear amplification using nonlinear components (LINC) is a method that improves linearity without cost in power efficiency. By summing two constant-envelope phase modulated signals this system exhibits high efficiency performance since the amplifiers used can be operated close to saturation levels and still get reasonably linear output

Design of LDMOS Balanced Power Amplifiers with Improved IMD Performance and Size Reduction

An LDMOS class-AB balanced power amplifier with an attempt to use reduced-size branch-line couplers in the divider/combiner parts is presented. The proposed amplifier with a center frequency of 2.14 GHz was designed. At center frequency a size reduction and improved intermodulation distortion are achieved, comparing with the conventional branch line couplers.

Waveguide resonators in planar form for oscillator and filter applications

In this paper a new direct integration of rectangular waveguide with planar circuits on the same substrate is presented. Since the design of such structure is very complex, first the substrate integrated rectangular waveguide is converted to an equivalent rectangular waveguide, so that the well established rectangular waveguide design theory can be applied. Periodic resonator at 3.5 GHz and 28 GHz is designed, simulated, fabricated and tested. This resonator structure is then used for filter and oscillator applications. Bandpass filter and oscillator at 28 GHz are designed and simulated. The proposed technique shows promising features such as reduced size, reduced cost and more compact resonator and filter structures, while maintaining easy fabrication process.