A stereo audio Σ∑ ADC architecture with embedded SNDR self-test

In this paper we present a new architecture for audio analog-to-digital converters (ADCs) that includes a Built-in Self-Test (BIST) technique for the test of the signal-to-noise and distortion ratio (SNDR). A periodical binary stream is generated in the chip in order to stimulate the converter. The reuse of the bandgap circuit already existing in the converter allows us to generate the test stimulus with a very small analog area overhead. The output response analysis is performed by means of a sine-wave fitting algorithm. The reuse of the digital filter already existing in the converter allows us to generate a synchronized reference signal necessary for the fitting algorithm. The BIST technique is equivalent to a standard test carried out with a sinusoidal signal at -12 decibels Full-Scale (dBFS). The total test time is 60 ms and the estimated BIST overhead area is 7.5% of the whole stereo converter area in a 0.13 mum CMOS technology. Experimental results show that the correlation between the embedded self-test and a sinusoidal standard test is excellent, with a SNDR error smaller than 1 dB.