A circuit is provided with a plurality current cells. The current cells each comprise a main current source and an auxiliary current source coupled in parallel. The main current source supplies a main current to a current output of the current cell, and the auxiliary current source supplies an auxiliary current to the current output of the current cell. The main current sources are weighted according to a first predefined waveform, and the auxiliary current sources are weighted according to a second predefined waveform which is different from the first predefined waveform.