Harmonic distortion in SD modulators (SDMs) implemented with fully-differential switched-current (SI) circuits. Closed form expressions are derived for the third-order harmonic distortion in both lowpass and bandpass SDMs. For the latter, the third-order intermodulation distortion is also deduced. Time domain behavioral simulations validate our approach.This work has been supported by the Spanish CICYT Project TIC 97-0580 and the ESPRIT Project 29621.Peer reviewed