Accurate Spectral Testing with Impure Test Stimulus for Multi-tone Test

Abstract

Analog-to-digital converters (ADCs) are among one of the world’s largest volume devices. ADCs are a necessary, vital mixed-signal integrated circuit (IC) component in almost every electrical device and system. One of the challenges is to accurately and cost-effectively test the continually better performance ADCs. For spectral testing of the ADC, one of the goals is to obtain dynamic performance of the ADC under test. The conventional test has become extremely difficult to implement accurately and cost-effectively, since the test stimulus to the ADC must have an even better purity than ADC under test with continuously higher performance. In addition, multi-tone tests require harmonics and spur, as well as the intermodulation must be accurately tested without influence from impure test stimuli. To resolve this issue, this chapter proposes a new method. This method uses the low-purity test stimulus instead of a high-precision test stimulus and passes the signal to two different cost-effective filters, and the output signals are then sampled by the ADC; by separating the nonlinearity from the source, the true ADC nonlinearity is accurately estimated. Then the dynamic performance of the ADC under test can be obtained. Extensive simulation results validate the functionality and robustness of the proposed method with different levels of impure test stimulus and different types or resolutions of the ADC under test. The proposed method greatly reduces the requirements on the test stimulus and is implemented into the board-level or on-chip high-performance ADC spectral testing and characterization.