Ricerc@Sapienza

The fully differential class-AB OTA topology by Peluso presents a poor Common-Mode Rejection Ratio (CMRR) and could become unusable for a common-mode gain larger than 1. We propose a local feedback loop that exploits internal nodes and triode-biased transistors to improve the CMRR with a limited power and area penalty. Simulations in 40-nm CMOS technology show a net improvement of the CMRR without affecting the differential-mode behavior; simulations of a sample- A nd-hold exploiting the proposed OTA topology are also presented.

The Voltage Conveyor (VCII) is the dual of the second generation Current Conveyor (CCII), and has received only a cursory attention in the literature, probably for lack of interesting applications. The VCII has a current buffer between Y and X terminals, and a voltage buffer between X and Z terminals. In this way, it makes it easier to sum (current) signals at the Y node, whereas CCIIs make it easier to sum (current) signals at the X node. Exploiting this difference between the two dual circuits, a very simple N-port synthesizer can be obtained using only N VCIIs.

New trends in neural computation, now dealing with distributed learning on pervasive sensor networks and multiple sources of big data, make necessary the use of computationally efficient techniques to be implemented on simple and cheap hardware architectures. In this paper, a nonuniform quantization at the input layer of neural networks is introduced, in order to optimize their implementation on hardware architectures based on a finite precision arithmetic. Namely, we propose a nonlinear A/D conversion of input signals by considering the actual structure of data to be processed.

Cloud Radio Access Network (C-RAN) or centralized RAN could be seen as a promising solution to deal the 5G requirements. Traditional C-RANs are organized as a three-element network, that contains Base Band Unit (BBU) pool, Radio Radio Remote Unit (RRU) and the network interconnecting BBUs and RRUs called fronthaul. The BBU provides baseband signal processing functions and the RRU provides Radio Frequency signal transmission and reception functions.

An open resonator compatible with X-band commercial spectrometers for electron paramagnetic resonance was designed and built. In the design process, resonators with different shapes and dimensions were compared by using ad hoc defined cavity figures of merit. Three cylindrical cavities operating on TEX11 modes with X = 1 , 2, 3, were designed taking into account a coupling iris and a slit for microwave magnetic field leakage. The cavities were further improved toward the homogeneity of the 100 kHz modulation magnetic field.

Fabry-Perot cavity antennas with polarization-reconfigurable omnidirectional conical beams are presented. The partially reflecting screen covering the antenna cavity is constituted by omnidirectional homogenized metasurfaces exhibiting rotationally invariant electromagnetic features, and specifically metal patterned screens are considered. The antenna operates on the first higher-order TMi and TEi leaky modes, whose phase and attenuation constants are properly equalized.

Application of femtosecond point-by-point inscription technique make it possible to form fiber Bragg gratings (FBGs) in different cores of multicore fibers as mirrors of laser cavity. In this paper, we present various configurations of Raman laser based on dual-core fiber. Due to the use of the inscribed FBG in the cavity of dual-core fiber, lasing threshold is reduced and the output power stability is increased, comparing to existing schemes.

To improve the gate oxide long term performance of MOSFETs in back side illuminated CMOS image sensors the wafer back is patterned with suitable through-silicon-trenches. We demonstrate that the reliability improvement is due to the annealing of the gate oxide border traps thanks to passivating chemical species carried by trenches.

Progress in MEMS technology continuously stimulates new developments in the mechanical structure of micro systems, such as, for example, the concept of so-called CSFH (conjugate surfaces flexural hinge), which makes it possible, simultaneously, to minimize the internal stresses and to increase motion range and robustness. Such a hinge may be actuated by means of a rotary comb-drive, provided that a proper set of simulations and tests are capable to assess its feasibility.

We experimentally demonstrate dual-polarization nonlinear frequency division multiplexing (NFDM) using the continuous spectrum in 1680 km of normal dispersion fiber, at the net data rate of 25.6 Gb/s. NFDM exhibits a gain of 0.4 dB in $Q$ -factor and 1 dB in total launch power when compared with burst mode OFDM. DGD penalties are shown to be negligible in NFDM transmission.