Jacek Konopacki

Noise Analysis And Noise Estimation Of An RF Sampling Front-end Using An SC Decimation Filter

In this paper we present the noise analysis of an SC filter for RF sampling and downconversion. The filter implementation is made in 0.12mum CMOS and is primarily intended for WLAN in the 2.4 GHz band and with 20 MHz signal bandwidth. The fundamental noise properties of switched capacitor circuits are discussed while deriving the necessary equations needed for the filter noise calculation. The influence of amplifier noise is also discussed, and a technique to remove low-frequency noise and DC offset from the amplifiers is presented. Finally, a noise estimation of a complete RF sampling front-end is made. Our results are verified by simulations using Cadence Spectre RF simulations

NIR finger vascular system imaging in angiology applications

Nowadays, in the age of technological development in various areas of life there is a growing interest in non-invasive techniques useful in medical examination. Angiology also called vascular medicine is a medical specialty with interest of diseases and disabilities of the human circulatory system. This domain uses different types of imaging. The acquired images are used for research, diagnostic, therapeutic or educational purposes. Different wavelengths and frequencies are used in the design of medical apparatus. In this paper the usability of near infrared light imaging is discussed and case studies of medical examinations are presented. There is a new approach with range area of applications in angiology.

Group delay and filter order estimation for least-squares design of IIR filters with unequal number of poles and zeros

A weighted least squares design of IIR filters has been considered in many publications. A problem that remains open is the choice of suitable filter order and suitable group delay of the desired phase response for the given set of filter specifications. This article introduces formulas to determine these parameters. Good results of parameters estimation are achieved for filters with a few poles (outside the origin of the z-plain) and an arbitrary number of zeroes. The examples are included in the paper to illustrate how to use the proposed formulas.

A Simplified Method for IIR Filter Design with Quasi-Equiripple Passband and Least-Squares Stopband

The modification of the weighted least squares (WLS) method for IIR filter design based on [5] is presented in the paper. The new algorithm allows to obtain quasi-equiripple approximation of the desired frequency response function in the passband and least squares (LS) approximation in the stopband. Even though the proposed method is very simple, it enables to obtain a larger passband-to-stopband ratio (PSR) of energies and a smaller passband ripple of the designed filter magnitude response when compared with the peak-constrained least-squares method.

SC filter for RF down conversion with wideband image rejection

In this paper, we present an SC filter for RF down-conversion using the direct RF sampling and decimation technique. The circuit architecture is generic and it features high image rejection for wideband signals and good linearity. An SC implementation in 0.12 mum CMOS suitable for an RF of 2.4 GHz and 20 MHz signal bandwidth is presented as a demonstrator. Simulation results obtained using Cadence Spectre simulation tools are included

Linear-phase IIR filter design based on FIR prototype with prescribed group delay

An IIR filter design procedure, based on amplitude and phase response approximations of the FIR prototype has been presented in the paper. The procedure comprises not only calculation of coefficients of both filters, but also their order calculation based on specified parameters. Numerous examples demonstrate the application of the proposed method for filter design tasks. Comparison of filter parameters obtained by the discussed approach and by the direct method has been presented.

D03: IIR filters design procedures based on digital frequency transformations

Abstract It is known that the transfer function of the desired digital IIR filter can beobtained from the analog lowpass filter by use of the digitizing procedures. Many useful design formulas for continuous-time filters relate to lowpass filters. The other types offilters, like highpass, bandpass and bandstop are obtained by frequency transformation. In general, analog or digital frequency transformations can be used, however available digital signal processing books give the practical design formulas for analog frequency transformation only. This paper proposes new procedures that applies digital frequency transformations.