How does a sigma-delta ADC work and why is it preferred for instrumentation?

Sigma-delta ADCs use oversampling (sampling much faster than Nyquist) and noise shaping. The modulator compares input to integrated error, producing a 1-bit stream. Noise is pushed to high frequencies by the integrator's noise-shaping. Digital decimation filter removes high-frequency noise and reduces data rate. Advantages for instrumentation: very high resolution (24-bit), excellent linearity, inherent anti-aliasing (from digital filter), low noise, and integrating action rejects 50/60 Hz. Trade-off is lower speed. Used in precision measurement, audio, and sensor interfaces.