Daniel Gasquet

Near-Field Electromagnetic Characterization and Perturbation of Logic Circuits

We propose here a nondestructive electromagnetic (EM) near-field test bench for both EM compatibility and susceptibility of circuits. This setup permits both the collection of the near field and injection without contact of a disturbing EM field, all through a probe. Exhaustive characterizations of probes are undertaken via simulations and experiments. According to their design, they are supposedly linked more to the electric or the magnetic field. Simulations of their EM behavior are undergone to fix their optimal geometries, leading to the best measurement performances. It is shown by both the simulations and the S-parameter measurements that their presence does not interfere with the electric behavior of the device under test. Then, logic circuits are characterized from the EM point of view, with the help of this test bench. Circuits are placed on three different printed boards: one double-sided low-frequency board without a ground plane and two single-sided boards with a ground plane and a design that is more or less optimized. EM near-field mappings highlight the strong field areas of the circuits. The need for a ground plane is highlighted. Field patterns on the traces are linked with those observed on microstrip lines. Then, an EM aggression is injected over a supposed sensitive zone of the circuit. Whichever printed board is considered, a parasitic signal superimposes itself on the output signal of the gates. Deepened studies are undergone to exhaustively explain the phenomena observed.

Probe Characterization for Electromagnetic Near-Field Studies

Probes used for contactless electromagnetic field capture or injection are characterized. Depending on the probe structure, they interact preferentially with the electric or magnetic field. The optimal size of the probes for broad-frequency-band measurements is investigated. However, it is shown particularly for the magnetic field probe that considerations about the size and the structures presented in this paper are not sufficient for a good discrimination between electric and magnetic fields. Then, the space resolution of near-field measurements is discussed, with application to the field capture of a microstrip line under operation.

Method for numerically computing the noise of devices

Abstract A numerical method for modeling the noise of one dimensional devices is presented, and is checked on a single space charge limited current diode, where analytical results are available.

Carrier spreading and diffusion coefficient in n‐Si

We have solved the transient {k} and space dependent Boltzmann equation in n‐type silicon. The transient distribution function f(k,z,t) is obtained in the k space and along the direction of the applied electric field (along the z axis). The material is assumed to be homogeneous so that the Poisson equation is not taken into account. Hence we can follow the spreading of a packet of carriers initially located around z=0. By a simple integration over the whole k space we obtain f(z,t), v(z,t), and e(z,t). The longitudinal diffusion coefficient is computed using the slope of the variance of the carriers’ positions.

NUMERICAL MODELING OF THE NOISE OF ONE DIMENSIONAL DEVICES

Two numerical methods for modeling the noise of one dimensional devices are presented. We briefly recall the technique very recently developped, to be used when the electrical variable of interest is the electric field, and we extend it to the case where the electrical variable of interest is the local potential. Numerical results are in quite good agreement with analytical ones for sclc diodes.

GENERATION RECOMBINATION NOISE IN p-Si AT 77 K

Noise and conductivity measurements in p-Si at 77K, up to 2.5kV/cm electric field strength, shows that three noise sources are significant: diffusion, G. R.,and 1/f noise. The diffusion coefficient versus electric field is given. The 1/f noise is important up to 10 GHz. The G.R. noise cannot be explained assuming two energy levels (impurity level and the valence band).