Frequency transformations for digital filters
It is shown that the reactance transformation for an analog filter corresponds to an all-pass function transformation in the case of a digital filter. It is further shown how this result could be used to obtain in a simple way the spectral transformations for digital filters derived by Constantinides.
Continuous time bandpass /spl Delta//spl Sigma/ modulators for a software defined radio
A mixed-signal continuous time band-pass delta-sigma modulator (CT BP /spl Delta//spl Sigma/) is a very attractive circuit category for applications where a time domain signal is to be processed in the digital domain. High-speed applications, such as wireless communications and software defined radio, are in need of a tunable bandpass filter in GHz range. We present a top level analytical model of a tunable 4/sup th/ order CT BP /spl Delta//spl Sigma/ modulator which is used for development of our mixed-signal continuous time behavioral circuit model. High speed CT /spl Delta//spl Sigma/ modulators are implemented using both "analog" and "digital" subblocks. We created mixed-signal models of the subblocks in order to efficiently perform simulations in the continuous time domain. The models were built out of primitives available in SPICE and Verilog-A/spl trade/. Simulation results confirmed validity of the analytical model.
On the ontology of particle mass and energy in special relativity
Einstein claimed that the fundamental dynamical insight of special relativity was the equivalence of mass and energy. I disagree. Not only are mass and energy not equivalent (whatever exactly that means) but talk of such equivalence obscures the real dynamical insight of special relativity, which concerns the nature of 4-forces and interactions more generally. In this paper I present and defend a new ontology of special relativistic particle dynamics that makes this insight perspicuous and I explain how alleged cases of mass–energy conversion can be accommodated within that ontology.