Suppression of delta-sigma DAC quantisation noise by bandwidth adaptation

Abstract

In this paper we present a system for adapting the bandwidth of a ∆Σ DAC based on the spectral contents of the input signal. By dynamically adjusting the bandwidth of the converter based on the transitory requirements of the input signal, quantisation noise can be suppressed further in frequency bands that are idle. It is shown how a compression scheme can be exploited to efficiently obtain the spectral information needed.A simulation model of the system is used to quantify the performance gain experimentally. The results obtained from the simulations substantiate the claim of a performance increase that outweighs the complexity incurred by the approach for certain classes of input signals.

On the design of IIR digital filter using linearized equation systems

“…Transfer functions having small number of poles have proven advantageous in comparison with classical designs, such as elliptic filters, in both digital [5] and analog discretetime filters [14]- [16]. Previously proposed methods using linear [4], [5] and nonlinear [6] equation systems had difficulties in handling small passband ripples, narrow passbands and sharp transition widths with a small number of poles.…”