Delta-sigma oscillators: versatile building blocks

Abstract

Delta–sigma modulators have long been used in signal-processing applications to simplify arithmetic operations. Their ability to trade bandwidth for quantization levels has been exploited to reduce hardware requirements and speed up computations. This paper will introduce a class of circuits called delta–sigma oscillators which use this property to efficiently generate spectrally pure analogue signals. Subsequently we will show how this approach can be extended to generate various multitone signals such as AM and FM signals. Delta–sigma modulators with various noise-shaping properties are at the core of these new designs. Owing to their small-silicon-area requirements and digital implementation, delta–sigma oscillators have been identified as an important building block for built-in self-test schemes for mixed-signal circuits and systems. They are also envisioned to be useful building blocks for various control and communication system applications. © 1997 by John Wiley & Sons, Ltd.