Denis Flandre

Testbed for IR-UWB based ranging and positioning: Experimental performance and comparison to CRLBs

In this paper we describe a testbed for impulse radio ultra wideband based ranging and positioning. We show the characteristics of the generated, transmitted and received pulses. We consider both the maximum likelihood estimator and a threshold-based estimator for the estimation of the time of arrival. We measure the variances for ranging and positioning and compare them to the Cramer-Rao lower bounds for range and position estimation. We discuss the impact of both false multipath component detection and false sidelobe detection on the estimation accuracy. The obtained variances are close to the Cramer-Rao lower bounds when the mainlobe of the first multi-path component is detected. In realistic multipath environments we can use a threshold-based time of arrival estimator in order to detect the first multipath component which may be missed by the maximum likelihood estimator. We show also that the errors on positioning due to false multipath component and sidelobe detection can be highly mitigated by increasing the number of receivers. For a radiated energy of 8.1 pJ and a distance of 5 meters between the transmit and receive antennas, the obtained accuracy is in the order of one centimeter.

Graded-Channel SOI nMOSFET Model Valid for Harmonic Distortion Evaluation

In this paper an evaluation of the harmonic distortion of graded-channel SOI nMOSFETs is performed. The analysis is carried out by comparing an analytical continuous model and experimental results. The total harmonic distortion, as well as the third and second order terms are used as figures of merit in this comparison. It is shown that GC SOI devices present better gain and linearity behavior than conventional devices and that these advantages are well described by the proposed analytical model. The results show that the proposed set of equations is able to describe the linearity behavior of GC devices, indicating its potential to be used in analog circuit simulation and design

On the Origin of the Excess Low-Frequency Noise in Graded-Channel Silicon-on-Insulator nMOSFETs

The origin of the low-frequency noise in graded- channel silicon-on-insulator nMOSFET is studied as a function of the back-gate bias at a low drain-to-source bias. It is shown that an excess noise peak that is correlated with the peak in the transconductance can be observed. This excess noise is due to a generation-recombination component in the low-frequency range, which is suppressed when the back gate is in accumulation mode.