The Terahertz (THz) band of the electromagnetic spectrum, also defined as sub-millimeter waves, covers the frequency range from 300 GHz to 10 THz. There are several unique characteristics of the radiation in this frequency range such as the non-ionizing nature, since the associated power is low and therefore it is considered as safe technology in many applications. THz waves have the capability of penetrating through several materials such as plastics, paper, and wood. Moreover, it provides a higher resolution compared to conventional mmWave technologies thanks to its shorter wavelengths. The most promising applications of the THz technology are medical imaging, security/surveillance imaging, quality control, non-destructive materials testing and spectroscopy. The potential advantages in these fields provide the motivation to develop room-temperature THz detectors. In terms of low cost, high volume, and high integration capabilities, standard CMOS technology has been considered as an excellent platform to achieve fully integrated THz imaging systems. In this Ph.D. thesis, we report on the design and development of field effect transistor (FET) THz direct detectors operating at low THz frequency (e.g. 300 GHz), as well as at higher THz frequencies (e.g. 800 GHz – 1 THz). In addition, we investigated the implementation issues that limit the power coupling efficiency with the integrated antenna, as well as the antenna-detector impedance-matching condition. The implemented antenna-coupled FET detector structures aim to improve the detection behavior in terms of responsivity and noise equivalent power (NEP) for CMOS based imaging applications. Since the detected THz signals by using this approach are extremely weak with limited bandwidth, the next section of this work presents a pixel-level readout chain containing a cascade of a pre-amplification and noise reduction stage based on a parametric chopper amplifier and a direct analog-to-digital conversion by means of an incremental Sigma-Delta converter. The readout circuit aims to perform a lock-in operation with modulated sources. The in-pixel readout chain provides simultaneous signal integration and noise filtering for the multi-pixel FET detector arrays and hence achieving similar sensitivity by the external lock-in amplifier. Next, based on the experimental THz characterization and measurement results of a single pixel (antenna-coupled FET detector + readout circuit), the design and implementation of a multispectral imager containing 10 x 10 THz focal plane array (FPA) as well as 50 x 50 (3T-APS) visible pixels is presented. Moreover, the readout circuit for the visible pixel is realized as a column-level correlated double sampler. All of the designed chips have been implemented and fabricated in 0.15-Âμm standard CMOS technology. The physical implementation, fabrication and electrical testing preparation are discussed.

The upgrades of High Energy Physics (HEP) experiments at the Large Hadron Collider (LHC) will call for new radiation hard technologies to be applied in the next generations of tracking devices that will be required to withstand extremely high radiation doses. In this sense, one of the most promising approaches to silicon detectors, is the so called 3D technology. This technology realizes columnar electrodes penetrating vertically into the silicon bulk thus decoupling the active volume from the inter-electrode distance. 3D detectors were first proposed by S. Parker and collaborators in the mid ’90s as a new sensor geometry intended to mitigate the effects of radiation damage in silicon. 3D sensors are currently attracting growing interest in the field of High Energy Physics, despite their more complex and expensive fabrication, because of the much lower operating voltages and enhanced radiation hardness. 3D technology was also investigated in other laboratories, with the intent of reducing the fabrication complexity and aiming at medium volume sensor production in view of the first upgrades of the LHC experiments. This work will describe all the efforts in design, fabrication and characterization of 3D detectors produced at FBK for the ATLAS Insertable B-Layer, in the framework of the ATLAS 3D sensor collaboration. In addition, the design and preliminary characterization of a new batch of 3D sensor will also be described together with new applications of 3D technology.

Modern communication and space systems such as satellite communication devices, radars, SAR and radio astronomy interferometers are realized with large antenna arrays since this kind of radiating systems are able to generate radiation patterns with high directivity and resolution. In such a framework conventional arrays with uniform inter-element spacing could be not satisfactory in terms of costs and dimensions. An interesting alternative is to reduce the array elements obtaining the so called "thinned arrays". Large isophoric thinned arrays have been exploited because of their advantages in terms of weight, consumption, hardware complexity, and costs over their filled counterparts. Unfortunately, thinning large arrays reduces the control of the peak sidelobe level (PSL) and does not give automatically optimal spatial frequency coverage for correlators. First of all the state of the art methodologies used to overcome such limitations, e.g., random and algorithmic approaches, dynamic programming and stochastic optimization algorithms such as genetic algorithms, simulated annealing or particle swarm optimizers, are analyzed and described in the introduction. Successively, innovative guidelines for the synthesis of large radiating systems are proposed, and discussed in order to point out advantages and limitations. In particular, the following specific issues are addressed in this work: 1. A new class of analytical rectangular thinned arrays with low peak sidelobe level (PSL). The proposed synthesis technique exploits binary sequences derived from McFarland difference sets to design thinned layouts on a lattice of P(P+2) positions for any prime P. The pattern features of the arising massively-thinned arrangements characterized by only P(P+1) active elements are discussed and the results of an extensive numerical analysis are presented to assess advantages and limitations of the McFarland-based arrays. 2. A set of techniques is presented that is based on the exploitation of low correlation Almost Difference Sets (ADSs) sequences to design correlator arrays for radioastronomy applications. In particular three approaches are discussed with different objectives and performances. ADS-based analytical designs, GA-optimized arrangements, and PSO optimized arrays are presented and applied to the synthesis of open-ended "Y" and "Cross" array configurations to maximize the coverage u-v or to minimize the peak sidelobe level (PSL). Representative numerical results are illustrated to point out the features and performances of the proposed approaches, and to assess their effectiveness in comparison with state-of-the-art design methodologies, as well. The presented analysis indicates that the proposed approaches overcome existing PSO-based correlator arrays in terms of PSL control (e.g., >1.0dB reduction) and tracking u-v coverage (e.g., up to 2\% enhancement), also improving the speed of convergence of the synthesis process. 3. A genetic algorithm (GA)-enhanced almost difference set (ADS)-based methodology to design thinned planar arrays with low-peak sidelobe levels (PSLs). The method allows to overcome the limitations of the standard ADS approach in terms of flexibility and performance. The numerical validation, carried out in the far-field and for narrow-band signals, points out that with affordable computational efforts it is possible to design planar array arrangements that outperform standard ADS-based designs as well as standard GA design approaches.