Low-IMD Two-Tone Signal Generation for ADC Testing

This paper describes algorithms for generating low intermodulation-distortion (IMD) two-tone sine waves, for communication application ADC testing, using an arbitrary waveform generator (AWG) or a multi-bit Sigma-Delta DAC inside an SoC. The nonlinearity of the DAC generates distortion components, and we propose here eight methods to precompensate for the IMD using DSP algorithms and produce low-IMD two-tone signals. Theoretical analysis, simulation, and experimental results all demonstrate the effectiveness of our approach.