High-Purity Sine Wave Generation Using Nonlinear DAC With Predistortion Based on Low-Cost Accurate DAC–ADC Co-Testing

Data converters are among the most widely used components in modern integrated devices and systems. A major challenge is to characterize their performances accurately and cost effectively. The analog-to-digital converter (ADC) standard test requires the input sinusoidal signal to be 3-4 b better than that of the ADC under test. Such high-quality sine waves are extremely difficult to generate and challenging to implement cost effectively. This paper presents a novel method that is capable of generating a high-purity sine wave using a nonlinear digital-to-analog converter (DAC), whose purity is significantly better than the original DAC output. In addition, with the aid of the low-cost DAC-ADC co-testing method, both DAC and ADC linearity information are accurately obtained with only 1 hit per code. Therefore, it is possible to add DAC linearity information to the DAC input codes, which cancels the nonlinearity of the DAC at output to achieve high purity. The proposed method has been validated by extensive simulation and measurement results, which demonstrated its accuracy and robustness against different resolutions, structures, or performance of the ADCs/DACs. With its low cost and easy test setup, such high-purity sine wave can be widely used for various applications where precision testing is required. In addition, the ADC and DAC linearity information is accurately obtained at the same time without any precision instrumentation, which is suitable for accurate DAC-ADC co-testing.