Jean-Marie Paillot

Electrostatic discharges from charged spheres approaching a grounded surface

Abstract A program based on the boundary element method enabled an accurate computation of the electric field in the gap between a conductive sphere of given charge and a grounded plate. The information on field distribution represented the input data of another program which estimated the dielectric strength of that gap in air at atmospheric pressure. In this way, it was possible to determine the critical conditions (charge, gap length) in which a discharge occurs between spherical objects of various sizes and a grounded surface.

Modeling and Characterization of Oscillator Circuits by Van der Pol Model using Parameter Estimation

In this paper, we present a new method for the modeling and characterization of oscillator circuit with a Van Der Pol (VDP) model using parameter identification. We also discussed and investigated the problem of estimation in nonlinear system based on time domain data. The approach is based on an appropriate state space representation of Van der Pol oscillator that allows an optimal parameter estimation. Using sampled output voltage signal, model parameters are obtained by an iterative identification algorithm based on Output Error method. Normalization issues are fixed by an appropriate transformation allowing a quickly global minimum search. Finally, the proposed estimation method is tested and validated using simulation data from a 1 GHz oscillator circuit in GaAs technology.

Computational estimation of ESD conditions between a charged body and a conductor of floating potential

The paper examines the conditions in which a discharge occurs between a charged body and a floating conductor, in air, at atmospheric pressure. The study, which primarily aimed at simulating a class of hazardous situations quite often met in the operation of electronic circuits, is also of interest to those involved in the research and development of electrostatic technologies for processing of particulate matter: separation of granular mixtures, precipitation of dust, spraying of powders. The boundary element method was employed for the analysis of the electric field in the gap between the charged body and the conductive disk at floating potential, located above a grounded plate. The computations were carried out for bodies of various shapes and sizes; some of them addressed the case of a grounded plate covered with an insulating layer of known permittivity. The data on field distribution represented the input data of another program, which estimated the breakdown conditions of that air-gap. The study enabled the estimation of the energy involved in this type of electrostatic discharge and the prediction of the related hazards.

A 2.4 GHz active phase shifter architecture for smart antennas control

This paper aims at developing the bases of a smart radio-communication prototype, able to modify the radiation patterns, both on emission and reception, according to the needs of the communication. Smart antenna is a well-known concept, allowing to increase the quality of the transmission and spectral efficiency. To control the radiation patterns, algorithms used in smart antenna techniques require precise amplitudes and phases generation. In this paper, vector modulators working as active phase shifters will be used in order to synthesize such amplitudes and phases. A theoretical analysis will be performed in order to quantify the impact of vector modulators mismatches on the synthesized amplitudes and phases. Furthermore, measurements of radiation patterns generated by a prototype at 2.4 GHz will be presented.

A 2.4 GHz 1-dimensional array antenna driven by vector modulators

This paper aims to develop an intelligent radio-communication prototype using multiple-antenna phased array whose bearing can be controlled electronically. Such a system has proved its efficiency in terms of gain and SNR improvement. The architecture presented in this article runs at 2.4 GHz with a bandwidth channel of 11 MHz which is well suited for WIFI 802.11b applications. This original system uses quadrature modulators as active phase-shifters, and noise sensitivity is studied and simulated to prove the interest of this architecture. A circuit is under tests and first elementary active parts RF measurements are given.

Cancellation of third order intermodulation currents in a two-stages amplifier topology

This paper gives a detailed description of a linearization technique using a two-stage amplifier. The first stage is used to generate third order intermodulation products (IMD3), which will be added to the input signal of the second stage in order to cancel the IMD3 at its output. The technique effectively improves the linearity of the system. To investigate the effect of IMD3 injection, analytical calculations of the drain currents for the fundamental frequencies f/sub 1/ and f/sub 2/ and for the third order intermodulation currents 2f/sub 1/-f/sub 2/ and 2f/sub 1/-f/sub 1/ are established without and with injection of intermodulation components at the input of the power stage. To evaluate the improvement provided by the proposed technique, a two-tone test at carrier frequency of 900 MHz is performed with a GaAs MESFET. The test procedure is described and measurements show a great improvement of IMD3. A carrier to third intermodulation ratio C/I3 of 55 dBc was achieved for a 19 dBm output power, compared with 25 dBc achieved without the first stage.This paper gives a detailed description of a linearization technique using a two-stage amplifier. The first stage is used to generate third order intermodulation products (IMD3), which will be added to the input signal of the second stage In order to cancel the IMD3 at its output. The technique effectively improves the linearity of the system. To investigate the effect of IMD3 injection, analytical calculations of the drain currents for the fundamental frequencies f/sub 1/ and f/sub 2/ and for the third order intermodulation currents 2f/sub 1/-f/sub 2/ and 2f/sub 2/-f/sub 1/ are established without and with injection of intermodulation components at the input of the power stage. To evaluate the improvement provided by the proposed technique, a two-tone test at carrier frequency of 900 MHz is performed with a MESFET. The test procedure is described and measurements show a great improvement of IMD3. A carrier to third intermodulation ratio C/I3 of 55 dBc was achieved for a 19 dBm output power, compared with 25 dBc achieved without the first stage.

A new class-C very low phase-noise Ku-band VCO in 0.25 µm SiGe:C BiCMOS technology

This paper presents a very low phase noise, fully integrated and differential Ku-band Voltage Controlled Oscillator (VCO) implemented in the QUBiC4X 0.25 μm SiGe:C BiCMOS process of NXP semiconductors. The originality of this design consists in using a new class-C architecture type. Under 5 V supply voltage and a maximum power dissipation of 123 mW, the proposed VCO features a worst case phase noise of -97 dBc/Hz at 100 kHz frequency offset from a 14.45 GHz carrier. The VCO is tuned from 13.59 GHz to 14.89 GHz with a tuning voltage varying from 1 V to 4.5 V and occupies 0.83×1.05 mm2.

A novel Q-enhanced LC switched-capacitor bandpass filter for digital wireless RF applications

In this paper, a novel architecture for a high-Q switched-capacitor bandpass filter, in 0.35 /spl mu/m CMOS, is presented and tested. The proposed architecture allows high selectivity tuning over a broad band in the radiofrequency range. This circuit is intended to replace surface acoustic wave (SAW) filters; it can be employed in the field of low-cost wireless communications as a subset for professional mobile phones [380-520 MHz]. Experimental results obtained from a prototype show a tunable center frequency range of 268 MHz [240-508 MHz], with quality factors up to 300.

A fully monolithic SiGe quadrature voltage controlled oscillator design for GSM/DCS-PCS applications

This paper describes the design and optimization in terms of phase noise of a fully monolithic SiGe Voltage Controlled Oscillator (VCO) with quadrature outputs. The proposed circuit is made of two cross-coupled differential VCOs, with integrated resonator, to ensure the quadrature outputs. The quadrature VCO core runs on 13 mA from a 2.7 V power supply. The simulated phase noise is about -140 dBc/Hz at 3 MHz frequency offset almost all over the tuning range. The oscillator is tuned from 1.44 GHz to 1.76 GHz with a tuning voltage varying from 0 to 3 V.

Graphical method for the phase noise optimization applied to a 6-GHz fully integrated NMOS differential LC VCO

This paper describes the design and the optimization in terms of phase noise of a fully integrated NMOS Voltage Controlled Oscillator (VCO) using a 0.25 μm BICMOS SiGe process. A three-dimensional phase noise analysis diagram and a graphical optimization approach is presented to optimize the phase noise of the VCO while satisfying design constraints such as tank amplitude, power dissipation, tuning range and start up conditions. At 2.5 V power supply voltage, the optimized VCO features a simulated phase noise of −118 dBc/Hz at 1 MHz frequency offset from a 6.12 GHz carrier. The VCO is tuned from 6.1 GHz to 7.9 GHz with a tuning voltage varying from 0 to 2.5 V, and a power dissipation of only 7.4 mW.