An eighth-order switched-current bandpass delta-sigma modulator is described. Simulations indicate that our 1.2pm CMOS implementation will achieve a S N R of 90dB in the band 10 MHzk150 KHz when clocked at 40 MHz. The modulator makes use of a switched-current resonator based on the N-path technique and the resonator employs regulated-cascode current-copiers to simultaneously achieve high speed ...

In this paper we present a method for stability analysis of high order Sigma-Delta modulators. The method is based on a parallel decomposition of the modulator. Using this presentation the general N-th order modulator could be considered as made up of N first order modulators, which interact only through the quantizer function. The decomposition helps us to extract the stability conditions of t...

An important factor affecting the performance of modulators is their tone behavior. A recent approach to alleviate the tone problem consists of moving the open-loop poles outside the unit circle. In this paper, we determine the frequency location of two dominant tones as a function of pole-location, and discuss the effect of pole location on the relative amplitude of low-frequency tones. Audio ...

This paper main intents to present a flying capacitor multilevel inverter based shunt active power filter(APF) with Sigma-Delta modulation. A multilevel Sigma-Delta modulation(SDM) control can be applied to control power section of APF intention to reducing sensitivity to flying capacitor voltage deregulation and mending modulator performance. In these control section of APF perfect harmonic ca...

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In this paper we investigate the relationship between the pulse-coded signal representation found in biological neurons and signals represented by first-order delta-sigma bit-streams. We show that a first-order delta-sigma bit-stream is a digital equivalent to a pulse-coded neural signal. By increasing the clock frequency, a delta-sigma bit-stream can approach a pulse-coded representation with ...

We examine a model for a bandpass Σ∆ modulator introduced by Feely and co-workers. This is shown to have the dynamics of a piecewise isometry of a union of convex polygons on the plane by an appropriate transformation of the linearised parts into normal form. Using these we show that the periodically coded regions form a packing of the phase space by circles and we link this system to a number ...

The soft γ–ray source GX 1+4 has been regularly monitored by the SIGMA telescope on board GRANAT since 1990. The accumulated data provides both period and spectral information on this source in the 35–150 keV range. The SIGMA telescope also allows a determination of a pulsed fraction. We report here on the last six years of the SIGMA data on GX 1+4. The general spin down trend is confirmed and ...

We compare the delta lenses, also known as d-lenses, of Diskin et al. with the c-lenses, known to be equivalent to opfibrations, already studied by the authors. Contrary to expectation a c-lens is a d-lens but not conversely. This result is surprising because d-lenses appear to provide the same information as c-lenses, and some more besides, suggesting that the implication would be the reverse ...