Digital-to-analog converter

A digital-to-analog converter maps a digital code to a physical analog output, usually an electric potential difference or electric current. For an ideal unipolar $N$-bit voltage-output converter with reference $V_{\mathrm{ref}}$, one common convention isIts step is $\Delta =V_{\mathrm{ref}}/2^N$ and its highest code produces $V_{\mathrm{ref}}-\Delta$, not the reference itself. Endpoint conventions differ between devices.

A three-bit converter with a 1 V reference gives levels $0,0.125,\dots ,0.875$ V. Sweeping the code slowly and measuring each settled level tests offset, gain and unequal step sizes. Rapid code changes add settling and transient errors. Holding each output until the next update creates a staircase; reconstructing a smooth waveform also requires suitable filtering and a sampling rate compatible with its bandwidth. Finite levels impose quantization even before analog noise and nonlinearity are considered.^[ref]