Digital test for the extraction of integrator leakage in first- and second-order modulators

A digital technique for evaluating the integrator leakage within first- and second-order ΣΔ modulators is proposed. It involves a very small amount of hardware, which makes it specially suitable for built-in self-test (BIST) implementation. Integrator leakage is known to be related to the converter precision and, hence, the proposed test technique serves as an indirect test of the signal-to-noise ratio (SNR) degradation. As an additional result, a strategy has been derived for digitally correcting the SNR loss due to integrator leakage in cascaded modulators.