Cost-Effective High Purity Signal Generator Using Pre-distortion

Sine waves are among the most widely used signals in many applications such as signal and device testing, measurement, communications, medical electronics, consumer electronics, etc. The high purity sine wave is crucial, as it is needed for high precision applications. Such high purity signals have become more challenging to generate, as the devices under test such as Analog-to-Digital Converters (ADCs) performances are becoming better, which the test signals need to have even better performances. This paper presents a cost-effective method to generate high purity sine waves using a nonlinear DAC. Based on a novel method that identifies the DAC nonlinearity, such information is fed back to the DAC input codes, cancels its nonlinearity, and results in a much better purity sine wave output. In addition, both linearity information of the DAC and ADC used can be accurately tested, which can be used for co-testing of the DAC and ADC. Extensive simulation results have verified the functionality and robustness of the proposed method, with different performances, structures or resolutions of the DACs and ADCs. The proposed method and system can be implemented on board or on chip that serves high performance high precision applications, with much lower design requirement and cost.