Piero Marietti

Analytic physics-based expressions for the empirical parameters of the Statz-Pucel MESFET model

The authors present a novel approach to the evaluation of the DC parameters of a semiempirical MESFET model: starting from the analytical expression of the drain current derived from a previously proposed physics-based model, they provide a method to calculate the empirical DC parameters of the so-called Raytheon model. The comparison between computed and measured DC characteristics is quite satisfactory on GaAs microwave FETs of 1 mu m or more gate length. By adding to the results obtained in this work an adequate model of the stray capacitances, the circuit performance can be optimized using the technological characteristics of active devices. >

A new dynamic differential logic style as a countermeasure to power analysis attacks

Power analysis attacks exploit the existence of ldquoside channelsrdquo in implementations of cryptographic algorithms to extract secret data. The scientific literature reports consolidated methods - such as Differential Power Analysis (DPA) and Simple Power Analysis (SPA) - for extracting a secret cryptographic key through the sensing of the hardware power consumption. We propose a novel dynamic and differential CMOS logic style as a countermeasure against power attacks on cryptographic devices. The proposed logic family exploits the idea of using signals with 3 possible states and operates with power consumption ideally independent on both the logic values and the sequence of data. We have designed a set of logic gates, flip flops and a simple S-BOX, and compared the S-BOX against previously published secure logic styles in terms of transistor count, power consumption and correlation between data and power dissipation.

Stability Criterion for Two-Port Network With Input and Output Terminations Varying in Elliptic Regions

New criteria to check the conditional stability of microwave amplifiers with input and output terminations varying in prespecified elliptic regions surrounding complex nominal values are proposed. Necessary and sufficient conditions are provided in terms of the immittance parameters lambdaij (i.e., zij, yij, gij, or hij): these conditions can be implemented in commercial computer-aided design tools and are suitable to be used as design goals within optimization routines. Since elliptic shapes accurately fit the real variability region of input and output terminations, the proposed criterion allows to impose stability in the actual tolerance range of terminations and therefore to improve the tradeoff between performance and stability under termination variations

An active balun for high-CMRR IC design

A circuit topology that provides large bandwidth single-ended to differential conversion is presented. The proposed cell is based on a differential pair where feedback on common mode signal provides about 6 dB conversion gain increase, together with attenuation of common mode signal. Small-signal characterisation is presented, based on a block decomposition of the cell. Measurements on a SiGe test IC show more than 5 dB of gain improvement with respect to a simple differential pair.

10-th order programmable low-pass CMOS integrated pulse-shaping filter

In this paper we present the design of a 10-th order pulse shaping filter for QAM modems. The filter has been fabricated in a standard 0.35 /spl mu/m CMOS technology and shows a 37 MHz typical bandwidth with 1:4 tuning capability, more than 60 dB attenuation at twice the bandwidth, less than 1.4 dB pass-band ripple and good linearity in the phase response. Current consumption of the filter core is about 70 mA from a 3.3 V supply. Experimental results in good agreement with post-layout simulations are presented.

Validation of a statistical non-linear model of GaAs HEMT MMIC's by hypothesis testing and principal components analysis

A distance-dependent non-linear statistical model of the active part of a very short-length HEMT-based MMIC, expressed in terms of principal components, is presented. A statistical model has been extracted for 0.1 mum GaAs HEMT devices and MMICs. Validation of the model is presented, based on principal component analysis and statistical hypothesis testing

High-speed CMOS-to-ECL pad driver in 0.18 /spl mu/m CMOS

In this paper, we present a CMOS-to-ECL converter and pad driver, to provide true negative ECL outputs from a positive-supply CMOS ASIC. The circuit exploits negative feedback loops to precisely set the output voltages corresponding to 0 and 1 logic ECL levels, and a high speed current switch to allow a bit rate of hundreds of Mb/s. Simulations using 0.18 /spl mu/m CMOS technology show a bit-rate in excess of 1 Gb/s, with high tolerance to temperature, load resistance and capacitance values.

Analysis and reduction of coupling effects between the photodiode and the MMIC amplifier in optical receivers

The effect of shunt-shunt feedback in monolithic transimpedance amplifiers for multiGbit per second optical receivers on the input impedance is considered in this paper. The main transfer function to be optimized is the transimpedance, but the input impedance should be taken into careful consideration to avoid unexpected peaking effects which can be a cause of performance degradation. The interconnection technique used to couple the photodiode to the MMIC amplifier has to be properly chosen in conjunction with the performance of the amplifier as current sink at the input port. We propose a design methodology based on the root-locus technique which can help the designer in the optimization of this kind of circuit with particular regard to the input peaking effects.

New topology for optical receivers based on a differential sensing of photodiode current

A new differential topology of optical receiver which is based on a differential sensing of the output current of the photodiode is presented in this paper. The receiver proposed here is made by a P-I-N photodiode and two amplifiers, each one amplifies the current furnished by a lead of the photodiode. It is intended for digital transmission systems which require a low-pass type response. By adopting a wide band transimpedance amplifier, this topology can increase the sensitivity of the optical receiver by 3 dB as well as the output level which is increased by 6 dB, and therefore reduces the gain requirement to the transimpedance amplifier and to the main amplifier.

Design approach and performance analysis of optical receivers based on input matching network

The performance of bandpass optical receivers can be improved using a lossless equalizer between the photodiode and the amplifier, as a consequence of the mismatch between the source and the input section of the amplifier. We propose two design approaches based on noise matching and on power matching, as well as a performance evaluation criterion to make comparisons between these different techniques. We have found the limit of noise performance of the approaches at a single frequency, and an upper bound, derived from the Bode-Fano limit, in a wide-band application for the power matching approach.