Luca Petruzzi

On the Robustness of CMOS-Chopped Operational Amplifiers to Conducted Electromagnetic Interferences

This paper deals with the robustness of low power chopped CMOS operational amplifiers (OpAMPs) to electromagnetic interferences (EMI) conducted at the device input stage. The main differences between chopped amplifiers and standard offset uncompensated ones are analyzed in terms of EMI susceptibility, achieving three main results. First, a new model is developed to show how chopping influences the amplifier susceptibility in a broadband sense, demonstrating that chopped OpAMPs generate a lower amount of EMI-induced offset from the nonlinear distortion with respect to standard ones because of the topological differences between the respective input stages. Second, a model to predict the effects of EMI appearing at the multiples of the chopping frequency is derived, showing that chopped OpAMPs can experience dc shift peaks because of the linear distortion of the disturbances whose frequencies hit the even multiples of the chopping frequency. Finally, the simultaneous presence of the technological offset and the offset produced by the nonlinear and the linear distortion of EMI in chopped OpAMP is illustrated by means of dedicated EMI susceptibility measurements performed on several devices designed to validate the analysis.

A 10 bit A-to-D converter development within power optimized BCD technology

This paper presents the development of a 10b ADC dedicated to the digitalization of a sensing current within advanced automotive applications. The presented ADC has been developed in a power optimized BCD technology, i.e. a process specifically optimized for power delivery and featuring signal processing capabilities. However it presents some limitations, i.e. highly non-linear capacitances, large mismatch, etc.. In this scenario a 10b ADC has been developed by means of a customized MATLAB model enabling the target performance achievements. The aim of this work is to study the effect of non-ideal components on the conversion performances focusing in particular on the technology limitations, like capacitors non-linearity and components mismatch. In order to achieve this, a Matlab model has been developed and then a demonstrator circuit has been designed at transistor level.

A mixed-signal multi-functional system for current measurement and stress detection

This paper presents the development of a mixed-signal multi-functional system for current measurement and electrical stress detection. The system is composed of a tracking ADC and a double range (a coarse and a fine one) current-steering DAC. The coarse range, designed for the full-scale input values [0A:108A], has a 5b resolution and it is used for the stress detection feature. The fine range is for lower input current values [4A:14A] and it is used for the current measurement, where more accuracy is required. With respect to the full-scale, the resolution of the fine range is 8b.