This work presents a \Sigma \Delta modulator prototype that gives experimental support to a fully digital Built-In Self- Test scheme. The goal of the proposed BIST is to provide digital signatures that are directly related to some important behavioural parameters of \Sigma \Delta modulators. As a result, parametric drifts can be detected before they seriously affect performance. The modulator required modifications are minimal and few gates would be necessary to implement a full BIST version, enabling infield self-test.