Description (under development)

Within the project, the following three Ph.D. theses have been conducted:

Ph.D. Thesis 1: "Design and Development of integrated circuits for Ultra Wideband systems, with emphasis on transmitter circuits".

Ph.D. Thesis 2: "Design and Development of integrated circuits for Ultra Wideband systems, with emphasis on receiver circuits".

Ph.D. Thesis 3: "Baseband Receivers/ Demodulators for wireless Ultra Wideband systems".

Title: "Design and Development of integrated circuits for Ultra Wideband systems, with emphasis on transmitter circuits".

Researcher: Michail Papamichail

Title: "Design and Development of integrated circuits for Ultra Wideband systems, with emphasis on receiver circuits".

Reasearcher: Dimitrios Mavridis

Abstract

This Ph.D. work focuses on design issues for the RF front end of an Ultra Wideband receiver, from 3.1 to 10.6 GHz.

The initial study explores the Low Noise Amplifiers (LNAs) where the various topologies for wideband operation are evaluated and two topologies are selected for fabrication and measurement. The first one is an amplifier with input bandpass LC filter and inductive source degeneration. The two versions of that circuit were fabricated for on wafer measurement as well as for board mounting, taking into account the bondwires. The measurement results indicate operation between 3 to 5 GHz. The second LNA topology builds on resistive feedback with current bleeding and uses an inductor for increasing the bandwidth, achieving operation from DC to 7 GHz.

The later phase of the work emphasized in the RF front end subsystem where an RF direct downconverted was designed, simulated and fabricated for operation for the whole 3.1 - 10.6 GHz band. The final circuit comprises a feedback LNA and two quadrature paths consisting of mixer, high pass filter and differential to single converter. In more detail, the amplified by the LNA signal feeds the single ended RF input of the mixers. The single to differential conversion is implemented by the transconductance stage of the mixer by a proposed topology that uses center tapped inductor. The mixer itself is a folded cascode gilbert cell allowing for lower supply voltage operation. The LO signal is fed externally in single ended mode and the signal is amplified and converted to differential on chip. Layout techniques are applied to ensure adequate balance and shielding among the high frequency signals. The downconverted signal is filtered to remove the DC offset and a converted changes its mode to single ended while providing 50 Ohm termination for measurement purposes.

Title: "Baseband Receivers/ Demodulators for wireless Ultra Wideband systems".

Reasearcher: Christos Thomos