Accurate Spectral Testing with Non-coherent Sampling for Multi-tone Test

Abstract

The multi-tone test has gained popularity among current test methods, since it offers flexibility in characterizing systems whose nonlinearities vary over signal frequency. Thus, it is impractical to test using the single-tone test. For multi-tone, non-coherent sampling is the major issue to perform accurate spectral testing, since precise control over each test tone frequency is very challenging to achieve. Such control may not be possible for on-chip testing. This chapter proposes a new method to resolve such issues. Based on the closed-form initial estimation of non-coherent fundamentals, more accurate estimation of non-coherent fundamentals is obtained. By replacing non-coherent fundamentals with coherent fundamentals, accurate spectral results are achieved. The accuracy and robustness of the proposed method are examined extensively by simulation and measurement results. Comparisons are made with the different methods. Combined with high accuracy, robustness, and computational efficiency, the proposed method is implemented for high-precision spectral testing, which relaxes the requirement of coherent sampling for multi-tone tests. In addition, this new method is also suitable for accurate signal spectral analysis when coherent sampling is not achieved.