The present invention is related to a digital circuit for use in a mixed-signal circuit. The digital circuit comprises: a first circuit for direct digital synthesis comprising a first phase generator (PG1) arranged for being fed with a phase generator input signal, a first phase-to-amplitude converter (PAC1) arranged for being fed with a phase from the first phase generator and for generating a first carrier wave output, and first signal combining means (R1) for combining the first carrier wave output with a first input signal, a noise generator (NG) arranged for generating a pseudo-random noise signal, combining means (S) for combining the pseudo-random noise signal and the phase generator input signal such that the phase generator input signal to the first phase generator (PG1) is randomised, a second circuit for direct digital synthesis comprising a second phase generator (PG2) arranged for being fed with the pseudo-random noise signal, a second phase-to-amplitude converter (PAC2) arranged for being fed with a phase from the second phase generator and for generating a second carrier wave output, and second signal combining means (R2) for combining the second carrier wave output with a second input signal, whereby the second carrier wave output combined with the second input signal is comprised in the first input signal.