CHARACTERIZING AND MINIMIZING SPURIOUS RESPONSES IN DELTA-SIGMA MODULATORS, ACTA UNIVERSITATIS OULUENSIS C Technica 414
|ISBN-13:||978-951-42-9748-9 || |
|Kustantaja:||Oulun yliopisto|| |
|Oppiaine:||Tekniikka, matematiikka|| |
|Sijainti:||Print Tietotalo|| |
|Tekijät:||NEITOLA MARKO || |
Oversampling data converters based on Delta-Sigma modulation are a popular solution formodern high-resolution applications. In the design of digital-to-analog or analog-to-digital Delta-sigma converters there are common obstacles due to the difficulties on predicting and verifyingtheir performance. Being a highly nonlinear system, a Delta-Sigma modulator’s (DSM)quantization noise and therefore the spurious tones are difficult to analyze and predict.
Multi-bit DACs can be used to improve the performance and linearize the behavior of DSMs.However, this will give rise to the need for linearizing the multi-bit DAC. A popular DAClinearization method, data weighted averaging (DWA) shapes the DAC mismatch noise spectrum.There are many variants of DWA, for low-pass and band-pass DSMs. This thesis proposes ageneralization which integrates a few published variants into one, broader DWA scheme. Thegeneralization enables expanding the tone-suppression studies into a larger concept.
The performance of one- or multibit DSMs is usually verified by simulations. This thesisproposes a simulation-based qualification (characterization) method that can be used to repeatedlyverify and compare the performance of multibit DSM with a DAC mismatch shaping orscrambling scheme.
The last contribution of this thesis is a very simple model for tonal behavior. The model enablesaccurate prediction of spurious tones from both DSMs and DWA-DACs. The model emulates thetone behavior by its true birth-mechanism: frequency modulation. The proposed prediction modelfor tone-behavior can be used for developing new tone-cancelation methods. Based on the model,a DWA linearization method is also proposed.