Signal generation using high-order Delta-sigma modulation

This work presents high-order, arbitrary-band delta-sigma oscillators. They are a class of digital circuits which, augmented with a minimum of analog circuitry requiring no trimming, generate fully programmable, high-quality analog sinusoidal signals. A generalization of previous work, they can meet arbitrary signal-band and SNR specifications at a minimum digital hardware cost, and without the previously reported stability problems. It is shown that multitone generation requires but simple modifications to the basic oscillator topology; this signal generation scheme is thus highly attractive for endowing mixed-signal integrated circuits and systems with self-test capabilities. Delta-sigma oscillators can be useful in other applications as well.An essential building block of delta-sigma oscillators is a one-bit digital delta-sigma modulator with unity Signal-Transfer-Function. A complete, computer-aided design method, relying on a novel high-order modulator topology allowing the use of power-of-two coefficients, is formulated and justified. Although the resulting modulators are aimed specifically at usage in delta-sigma oscillators, they can find applications in oversampled D/A conversion in general as they require a minimal amount of digital hardware.DSMOD is the computer-aided design tool which was developed to automate the design, simulation and prototyping processes. It implements a number of involved design algorithms, and allows for a quick comparison of theoretical, simulated and prototype behavior, with the use of a graphical user interface. It is written mostly for MATLAB and is thus highly portable and expandable.The measurements performed on prototypes prove the soundness, flexibility and efficiency of DSMOD. They also prove that low hardware cost and high performance levels are attainable with the novel delta-sigma modulator and oscillator topologies presented here