Digital sigma delta modulation for on chip signal generation

A new method for generating analog signals with very low complexity and hardware requirements has recently been introduced. It consists of using sigma delta modulators in the loop of the digital resonator. This paper focuses on a class of these circuits called sigma delta oscillators which use the modulator ability to trade bandwidth for quantization levels in order to efficiently generate spectrally pure analogue signals. Sigma delta modulators with various noise shaping properties are at the core of these new designs. Owing to their small silicon area requirements and digital implementation, sigma delta oscillators have been identified as an important building block for BIST scheme for mixed signal circuits.