Sample Rate

Sample rate is the rate at which digital data is transferred from the memory to the digital-to-analog converter (DAC). According to Shannon’s Sampling theorem, a digital waveform must be updated at least twice as fast as the bandwidth of the signal to be accurately generated. Ideally, a sample rate many times greater than the frequency of the signal produces accurate waveforms. A higher sample rate also captures more waveform details. The following figure illustrates a 1 MHz sine wave generated by a sampled 2 MS/s DAC and a 20 MS/s DAC. The faster DAC generates 20 points per cycle of the expected signal compared with 2 points per cycle with the slower DAC. In this example, the higher sample rate more accurately defines the waveform shape.