An apparatus comprising a scrambler having a plurality of scrambler inputs and 2N scrambler outputs, and a unary-weighted digital to analog converter (DAC) connected to scrambler to generate an analog output signal based on the 2N scrambler outputs. The scrambler has N unique scrambling stages arranged in order between the scrambler inputs and the scrambler outputs from a first scrambling stage to a last scrambling stage. Each of the N unique scrambling stages has a plurality of stage inputs and outputs, with the stage inputs of the first scrambling stage connected to the scrambler inputs, the stage outputs of each scrambling stage except the last scrambling stage connected to the stage inputs of a next scrambling stage, and the stage outputs of the last scrambling stage connected to the scrambler outputs. Each of the N unique scrambling stages is operable to pass signals at the inputs to the outputs in either an unscrambled or scrambled state under control of a control bit provided by an N-bit entropy signal. When an N+1 bit input signal is applied to the scrambler inputs and the N-bit entropy signal is randomized the analog output signal from the DAC has improved linearity compared to the analog output signal generated from a non-scrambled input, and when a test input signal is applied to the scrambler inputs and the entropy signal is swept through 2N orthogonal values the analog output signal from the DAC indicates whether a fault exists in one of the scrambler and the DAC.