Quantization Noise

Signal Dynamics

Full scale input signals experience theoretical signal to noise ratios defined by six point zero two times the bit count plus one point seven six decibels. Low amplitude input signals spanning only a few quantization steps generate correlated, non white noise that creates harmonic distortion. Dithering techniques inject small amounts of out of band random noise to decorrelate quantization error from the input signal.

Oversampling spreads total quantization noise energy across wider bandwidths, allowing digital decimation filters to remove high frequency noise power. Effective number of bits represents actual converter performance under dynamic operating conditions.

Circuit Optimization

Metrological sourcing requires matching converter resolution to intrinsic sensor noise floors to avoid wasting digital bandwidth or truncating analog precision. Anti aliasing filters must attenuate input signals above the Nyquist frequency to prevent high frequency noise folding into baseband signals. Input buffer amplifiers must exhibit lower noise and distortion than the converter least significant bit voltage.

Voltage reference stability directly impacts quantization step uniformity, where reference noise translates directly into conversion error. PCB layout requires strict isolation between analog inputs and digital switching lines to maintain low noise floors.

Performance Verification

Fast Fourier transform analysis of digitized pure sine wave inputs quantifies signal to noise and distortion ratios under standardized test conditions. Code transition noise testing determines whether missing codes or unequal step widths degrade converter linearity. Dynamic range measurements confirm that converter performance matches theoretical data sheet specifications across operational sampling rates.

Rejection thresholds target excessive integral non linearity and spurious free dynamic range degradation. Quantization errors dictate the ultimate resolution floor of digitally integrated instrumentation.