Jeffrey O. Coleman

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The stopbands of a cascaded integrator-comb (CIC) decimation filter are ordinarily very narrow, as each results from a single multiple zero. Here response sharpening with a Chebyshev polynomial, using a previously reported CIC variant, separates each such multiple zero into an equiripple stopband. By trading unneeded depth at stopband center for improved(More)
Staggering the sample times for alternate elements of a linear antenna array is shown to halve the usual Nyquist sample-rate bound of twice the one-sided signal bandwidth while preserving alias-free mapping between spectral components and plane waves in the far field. This approach can be used on transmit or receive and with lowpass or bandpass sampling,(More)
This paper focuses on the analysis of nonlinear inter-symbol interference (ISI) in RF bandpass delta-sigma power digital-to-analog converters (DACs). Digital RF transmitters based on direct delta-sigma modulation have been proposed for efficient linear multi-functional radios. We show that a realistic one-bit DAC limits the linearity of such a transmitter.(More)
Here we formulate second-order cone programs (SOCPs) for synthesizing complex weights for far-field directional (single-point mainbeam) patterns for narrowband arrays. These formulations, while constructed here with the uniform circular array (UCA) in mind, are actually quite general in that they control the arbitrary-pol sidelobe level (SLL) and co-pol SNR(More)
Random-process autocorrelations and crosscorrelations in three dimensions here provide computationally efficient mean-square-error and average-gain measures to control main beam and sidelobe characteristics in convex optimization of far-field beamforming coefficients for large wideband arrays. An example optimized with the ultra-efficient interior-point(More)
A systematic approach is proposed for the individual or joint design of FIR filters to meet specifications on either a single filter or an embedding system (possibly multirate). System power gains in response to particular input spectra are optimized using a generalized eigenvector method. Numerical integration is avoided through a time-domain formulation.(More)