Yves Rolain

Parametric identification of transfer functions in the frequency domain-a survey

This paper gives a survey of frequency domain identification methods for rational transfer functions in the Laplace (s) or z-domain. The interrelations between the different approaches are highlighted through a study of the (equivalent) cost functions. The properties of the various estimators are discussed and illustrated by several examples. >

Low-Area Active-Feedback Low-Noise Amplifier Design in Scaled Digital CMOS

The emerging concept of multistandard radios calls for low-noise amplifier (LNA) solutions able to comply with their needs. Meanwhile, the increasing cost of scaled CMOS pushes towards low-area solutions in standard, digital CMOS. Feedback LNAs are able to meet both demands. This paper is devoted to the design of low-area active-feedback LNAs. We discuss the design of wideband, narrowband and multiband implementations. We demonstrate that competitive RF performance is achievable thanks to CMOS downscaling, pleasing many applications because of their low cost (digital CMOS) and low area (bondpad size).

Brief Fast approximate identification of nonlinear systems

In this paper, a method is presented to extend the classical identification methods for linear systems towards nonlinear modelling of linear systems that suffer from nonlinear distortions. A well chosen, general nonlinear model structure is proposed that is identified in a two-step procedure. First, a best linear approximation is identified using the classical linear identification methods. In the second step, the nonlinear extensions are identified with a linear least-squares method. The proposed model not only includes Wiener and Hammerstein systems, it is also suitable to model nonlinear feedback systems. The stability of the nonlinear model can be easily verified. The method is illustrated on experimental data.

A 52 GHz Phased-Array Receiver Front-End in 90 nm Digital CMOS

The commercial potential of the 60 GHz band, in combination with the scaling of CMOS, has resulted in a lot of plain digital CMOS circuits and systems for millimeter-wave application. This work presents a 90 nm digital CMOS two-path 52 GHz phased-array receiver, based on LO phase shifting. The system uses unmatched cascading of RF building blocks and features gain selection. A QVCO with a wide tuning range of 8 GHz is demonstrated. The receiver achieves 30 dB of maximum gain and 7.1 dB of minimum noise figure per path around 52 GHz, for a low area and power consumption of respectively 0.1 mm2 and 65 mW. The presented receiver targets 60 GHz communication where beamforming is required.

Brief Frequency response function measurements in the presence of nonlinear distortions

In this paper, we deal with the measurement of the frequency response function (FRF) of linear dynamic systems in the presence of nonlinear distortions. It is shown that it is possible to detect, qualify and quantify the nonlinear distortions during a broadband frequency response measurement. Advises are formulated how to get the best measurements under these conditions. All results are illustrated by experiments.

A 57-to-66GHz quadrature PLL in 45nm digital CMOS

The worldwide available frequency bands around 60GHz offer new opportunities for high-data-rate communication. Despite the large amount of research on CMOS mm-wave frequency generation, current state-of-the-art mm-wave PLLs [1–5] do not achieve a tuning range that is wide enough to cover the worldwide union of bands around 60GHz (57 to 66GHz), with some margin for process and temperature variations. Achieving a large tuning range is hampered by the limited varactor tunability at 60GHz, and the need for a high-frequency prescaler with a wide locking range.

A 52GHz Phased-Array Receiver Front-End in 90nm Digital CMOS

In this paper, a CMOS implementation of phased-array receiver front-end, based on a widely tunable QVCO is presented. Each path achieves 30dB of gain and a minimum NF of 7.1dB, yielding a system NF of 4.1dB. The overall current draw is 54mA from a 1.2V supply. Additionally, a calibration procedure to mitigate the analog impairments imposed by the proposed implementation is demonstrated.

Fully automated spectral analysis of periodic signals

In this paper, we propose a method that allows to make a fully automated spectral analysis of a periodic signal, including a noise analysis, without any user interaction. The only action required from the user is to provide a data record that contains more than two periods of the signal (no integer number of periods is required). No synchronization between the generator and the data acquisition is needed, and different sampling rates are allowed (no integer number of samples/period is required).

Best conditioned parametric identification of transfer function models in the frequency domain

It is shown that rational transfer function models based on orthogonal Forsythe polynomials minimize the condition number of the Jacobian of estimators in a least-squares framework. As a result, very high order linear time-invariant systems can be identified. The numerical stability of the estimation of the parameters and their derived quantities (zeros, poles, ...) are obtained. Statistical uncertainty bounds are provided. The method is illustrated on a 100th order simulated system and a 120th order measured beam-structure. >

Experimental characterization of operational amplifiers: a system identification Approach-part I: theory and Simulations

Using specially designed broadband periodic random excitation signals, the open loop, the common mode, and the power supply gains of operational amplifiers are measured and modeled. The proposed modeling technique: 1) takes into account the measurement uncertainty and the nonlinear distortions, 2) gives information about possible unmodeled dynamics, 3) detects, quantifies, and classifies the nonlinear distortions, and 4) provides opamp parameters (time constants, gain-bandwidth product, etc.) with confidence bounds. The approach is suitable for the experimental characterization of operational amplifiers (see [23]) as well as the fast evaluation of new operational amplifiers designs using network simulators (see Part I). Part I describes the modeling approach and illustrates the theory on simulations.