CMOS Active Filter Research Articles

Uncertainty Quantification of CMOS Active Filter Circuits: A Non-Intrusive Computational Approach Based on Generalized Polynomial Chaos

Semiconductor fabrication technologies as applies to the nanometer-era paradigms of nowadays have rendered uncertainty quantification analyses through component-level parameters compulsory and indispensable. Frequency responses of CMOS active filters are invariably observed to be affected by probabilistically modelled parameter deviations, and in this article the focus is on the fast and accurate quantification of the uncertainties pervading CMOS active filters in terms of their magnitude frequency responses. Previous work dominantly has preference for the widely recognized non-intrusive Monte Carlo methods, which bring about a disproportionately high computational burden. Also discomfitures are observed to arise due to apparently inadequate ensemble volumes and a limited variety of distribution functions that are chosen to be utilized, along with seemingly insufficient means of resulting data visualization and the lack of accurate probabilistic quantification. Generalized Polynomial Chaos (gPC) based stochastic spectral techniques, which usually offer reduced computational complexity with respect to Monte Carlo, targeting CMOS active filters do not seem to have drawn much attention; the few related publications offer utility in a limited scope of electronic components. In this article, we carry out uncertainty quantification analyses in order to compute partial or approximate stochastic characterizations of the magnitude frequency responses of several multi-component CMOS active filter circuits with the gPC-based stochastic collocation technique. The pertaining inherent non-intrusive nature is exploited, and the stated issues associated with the previous work are addressed. We utilize a stokhos-based MATLAB/C++ toolbox of our own design, on whose software architecture, features, and facilities we provide profound details, and present performance comparisons with Monte Carlo along with intuitive and insightful comments, in an endeavor to suggest that such observations may prove to be beneficial to circuit designers.

Improved Fully Differential Low Power Active Filter

This paper relates the new topology and simulations of a fully differential CMOS active filter for mm wave band applications. The advantages of the differential topology over the single ended one are discussed and the quality factor is tuned to insure application requirements, including narrow bandwidth and high selectivity due to a differential negative resistance that reuses the filter’s current. Using this topology enables independent tuning of the quality factor and low power consumption while compensating the resistive loss of the filter. Very high filter performance was obtained with the simulated active inductor based active filter that was designed using CMOS 0.35 µm technology from AMS foundry and that resonates at 30 GHz with a high quality factor of Q > 500.

A simple continuous-time equalizer for use in magnetic storage read channels

A four-pole continuous-time equalizer has been developed to minimize the error rate in rigid-disk magnetic storage channels employing peak detection at high recording densities. The design process consisted of two parts. A nominal model of the disk drive characteristics in the time and frequency domains was obtained from digitized waveforms at the output of a read-head amplifier in a disk drive system. The relative performance of candidate equalizers was studied by subjecting them to the measured data waveforms and then either estimating or measuring the resulting bit error rate in a simulated peak detector, operating on the equalized waveforms. The equalizer outperforms more complex structures proposed for this task and is well suited for implementation as an analog CMOS active filter with low power dissipation. Its constellation of four poles and a zero appears to be useful for several types of magnetic media.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

CMOS active filter design at very high frequencies

A study of the limitations of active CMOS filters at high frequencies suggests automatic means to compensate imperfections in the filter response introduced by active devices. The effects of nonzero FET output conductance, limited frequency response and noise on the filter characteristics, and dynamic range are analyzed, particularly for filters with high Q components. These are used to demonstrate a 3- mu m CMOS realization of a fourth-order bandpass filter with a 250-kHz passband centered at 12.5 MHz. The filter demonstrates that the maximum frequency of filter operation is not as seriously limited by device f/sub T/ as was previously thought, but that automatic means may be used to tune out the imperfections introduced in the filter elements by the limited voltage gain and frequency response of transistors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>