A Fully Integrated BIST $\Delta \Sigma $ ADC Using the In-Phase and Quadrature Waves Fitting Procedure

This paper demonstrates a fully integrated builtin self-test (BIST) ΔΣ analog-to-digital converter (ADC) based on the proposed in-phase and quadrature waves fitting (IQWF) procedure. The IQWF procedure enables accurately measuring the phases and amplitudes of test responses so as to enhance the test accuracy of the BIST circuitry. The all-digital BIST circuitry, with on-chip stimulus generator and response analyzer, conducts single-tone functional tests to test for the ADCs characterization results such as signal-to-noise-and-distortion ratio (SNDR), dynamic range (DR), frequency response, input-referred offset, and gain error. Since the IQWF procedure is performed successively in real time, the BIST circuitry does not need huge memory to store all the output samples like conventional fast Fourier transform (FFT) analysis does. The overall hardware overhead only consists of 16.6 k digital gates. The fully integrated BIST ΔΣ ADC has been fabricated in 0.18-μm CMOS. Measurement results show that the BIST circuitry reports a peak SNDR of 88.0 dB and a DR of 92.6 dB while the corresponding FFT-based analog tests result in 88.8 and 94.1 dB, respectively. Particularly, the BIST circuitry achieves a test bandwidth as wide as the ADCs 20-kHz rated bandwidth, which is the widest to the best of our knowledge. The proposed BIST ADC can be tested without costly external test resources and is thus well suited for the applications in which conventional test resources are not available such as 3-D ICs.