AC Voltage Reference Using the Fundamental of DAC Stepwise-Approximated Sine Waves

The fundamental of digital-analog conversion (DAC) stepwise-approximated sine waves (SASW) is calculable based on the amplitude of each step. Using direct comparison method in specific frequency, the fundamental of DAC SASW can be used as ac voltage reference. A normal commercial DAC-based ac voltage system for direct fundamental comparison using lock-in amplifier is constructed to demonstrate the practicability of this method. The DAC quantization errors and the influences of rising times and transients between adjacent steps affecting its fundamental wave are also studied and evaluated. The results show that the fundamental of SASW could be used as ac voltage reference up to audio frequency range.