In this paper a Track-and-Hold Amplifier (THA), designed in a low cost 0.35μm SiGe 60GHz technology is presented. Thanks to the joint action of a novel input buffer and a suppression feedthrough architecture, it is able to guarantee 62dB Total Harmonic Distortion(THD) up to a frequency of 2.2GHz with 0.9Vp-p differential input at a sampling rate (Fs) of 2.5GS/s. The THA core draws about 145mA from 3.5V supply.

The paper describes a Track and Hold Amplifier (THA) suitable for RF sampling and Software Defined Radio receivers where high speed and high resolution are required. The reported THA is based on two main techniques: one for minimizing the differential droop rate and one for improving the HD3 in track mode. Measurements results show that the adopted solutions are both effective. In the desired input band around 1GHz, at the desired sub-sampling frequency (0.5GS/s) the THA provides a linearity compatible with 12-bit (Spurious Free Dynamic Range, SFDR). Moreover at the maximum achievable sampling frequency (1.5GS/s) the performances are quite constant and the resolution is compatible with 11-bit (SFDR) up to an input frequency of 1GHz.

In this paper a Track-and-Hold amplifier (THA), designed in a low cost 0.35μm SiGe 60GHz technology, suitable for SDR applications, is presented. With the implementation of a novel input buffer, the circuit shows a 3dB bandwidth of 7GHz and a distortion better than 50dB up to, about, that frequency during Track phase. Simulations show a THD better than 50dB up to a frequency of 5.77GHz at 2GS/s and a "reconstructed" 3dB full power bandwidth (FPBW) of 5.86GHz. The circuit draws about 220mA from 3.3V supply, considering all the sampling stage, the output buffer and clock driver.

The paper describes a Track and Hold Amplifier suitable for high-speed and high resolution applications like Software Defined Radios. Thanks to the adopted techniques to maximize the resolution without reducing the sampling frequency, all the non idealities limiting the equivalent number of bits have been taken into account. In particular a novel technique to reduce the third harmonic distortion has been proposed and exploited. Post-layout simulations show that the performances are quite constant and the linearity is compatible with 11-bit (SFDR) at Fs= 1.5GS/s up to a frequency 1GHz.

In this paper a new high resolution GPS-based system for indoor is presented. The common systems used for this purpose are not very accurate and usually expensive. The proposed approach allows to obtain systems which are both very accurate and low cost. It is based on the wideband spread spectrum technique at 24 GHz, and achieves an accuracy better than 0.5 millimeter even when the target is moving. The peculiarity of this positioning system compared to others is the fully analog correlation which improves the cost-effectiveness of the system.

The impact of human activities over the environment experienced a dramatic growth in the last century often giving rise to unpredictable effects. As a matter of fact, the impact of un-regulated industrial activities over the last century has induced severe variations in the atmosphere resulting in changes in weather manifestations which, in turn, increased the risk of hurricanes, excessive rain precipitations and so on. Joint to these aspects, wild urbanization of wide areas surrounding the cities exasperates the hazards deriving from landslides, floods, fire in the green areas, etc.. The management of environmental hazard could strongly benefit from the advances in electronics, telecommunications and informatics, often related as Information and Communication Technologies (ICT), which made available a wealth of sensors of different type which can be suitably employed in early monitoring and risk assessment and management. Advanced environmental risk management requires high performance integrated multi-sensor systems enabling fast and accurate detection of disparate data and critical situations that must then be analyzed through scientific modeling and intelligent supervisory interpretation, in order to devise and put at work correct strategies for monitoring and contrasting wild land fires, landslides, floods and varied similar natural hazards. Multi-sensor data fusion and integration still seems a relevant technological challenge when dealing with such complex devices as Thermal/IR imaging systems, radar/lidars, sophisticated Visible cameras, plus the emerging distributed wireless sensor networks (WSN) - with embedded sensing, computing and communication capabilities per each node - that may collect simple weather/hydro/chemical measures on the field under observation. This short exposition makes an assessment of the technology advances in integrated multi-sensor networks, starting by the illustration of the structure and some preliminary results of the ERMES Project (Enhance Risk Management through Extended Sensors), sponsored by the Italian government under grant #PON01-03113.

The paper thoroughly describes the operation of a wideband Distributed VCO (DVCO) which allows to design VCOs with a good trade off among wideband and phase noise. The general condition of oscillation is reported. Two innovative tuning techniques are proposed and described. Each solution has been used to design and fabricate a DVCO prototype. The first one is a simplified Printed Circuit Board prototype based on the switched-capacitors banks tuning technique. It provides a tuning range of 360 MHz from 1.52GHz to 1.88GHz sub-divided in two sub-bands: 1.52-1.78GHz and 1.69-1.88GHz The second one is a fully integrated VCO which adopts the new approach called “switched-cells tuning technique”. It provides the following measured tuning range subdivided in four sub-bands: 207MHz around 900MHz, 291MHz around 1.5GHz, 392MHz around 1.8GHz and 199MHz around 2.4GHz. According to the reported theory, the results show the applicability of the proposed Distributed VCOs for advanced transceivers.

A novel input buffer for very high speed and high resolution track-and-hold amplifiers has been developed in BiCMOS technology. The configuration retains the benefits of a cascode configuration in terms of distortion and adaptability to various advanced switched-emitter (source)-follower based architectures while maintaining supply requirements similar to a conventional degenerated common emitter amplifier. To demonstrate the advantages of the presented architecture a distortion analysis has been carried out. The closed form formulas show very good agreement with Spectre® simulations using complete models.

A comprehensive study on the role of the phase errors distribution on the performances of the phased array systems has been led using a complete and behavioral model for radiation-pattern characteristics. The used model has many input parameters and it has a lot of features, such as parameters simulations with results analysis, unconventional two-dimensional color graph representation capability in order to show more clearly the results. The results of the study have been discussed and reported. The main achievement of this work is the demonstration that the RMS phase error is a valuable figure of merit of phased array systems but it is not sufficient to completely describe the behavior of a real system. Indeed, this work has shown how the phase errors distribution actually affects the performances of the phased arrays antennas.

A 10-bits Phase Control Block (PCB) in 0.35 μm SiGe technology for active phased arrays is presented. The proposed PCB has been used instead of a DDS in an advanced DDS-PLLs microwaves phase shifter. The PCB is composed by a counter and a set of comparators. The clock frequency is 2GHz and the PCB output frequency is 1.953MHz. The block generates 1024 phase-shift values, each one corresponding to a given phase word. A DSP or a microcontroller can be used to set the desiderated phase values. Each block is designed in ECL logic with a 3.3V supply voltage. The phase shifted outputs of the PCB are used by the PLLs as references signals. The phase shifter output frequency is 2.4GHz. As expected from the theory, the rms phase error is less than 0.1° compatible with the 10-bits PCB resolution confirming the validity of the proposed solution.

The paper introduces a linearization technique based on a modified complex gain predistorter. The look-up table (LUT) digital adaptive predistortion (PD) approaches are effective for power amplifier (PA) linearization for reducing the PA power back-off and increasing the efficiency. Unlike other LUT predistorter based on uniform spacing of the LUT entries, the paper proposes a robust and behavioral method. The density of the table entries is directly proportional to the amplifier nonlinearity so the optimum table spacing could be realized. Besides, the proposed algorithm is able to optimize the LUT spacing without prior knowledge of the PA characteristics or input signal statistics and the LUT index calculation is made by a simple and fast algorithm.