SigmaDeltaWandlung

SigmaDeltaWandlung, also known as Sigma-Delta modulation or Sigma-Delta conversion, is a method used in signal processing to convert analog signals to digital form (and, in some variants, to realize digital-to-analog conversion). The approach achieves high resolution by oversampling the input signal and shaping the quantization noise away from the band of interest.

The core concept involves an oversampled feedback loop in which a loop filter, often consisting of one or more integrators, processes the input. A quantizer provides a coarse digital output, and the resulting quantization error is fed back through the loop. This feedback shapes the spectrum of the noise so that most of it lies at higher frequencies, where it can be removed by a digital decimation or reconstruction filter.

Architectures vary from first-order to higher-order designs. A single integrator defines a first-order sigma-delta, while two or more integrators yield higher-order variants with stronger noise shaping. Multi-stage noise shaping and sophisticated digital decimation filters are common in practical implementations to recover a high-resolution digital signal with low in-band noise.

Applications are widespread in electronics, especially in audio ADCs, instrumentation, and communication systems. SigmaDeltaWandlung enables high effective resolution with relatively simple analog circuitry, relying on digital processing to complete the conversion. The trade-offs include latency from the decimation and reconstruction filters, as well as potential stability considerations in higher-order configurations.

Historically, sigma-delta techniques emerged in the 1960s and 1970s and have since become mainstream due to robustness, linearity, and compatibility with integrated-circuit fabrication.