a pulse generator circuit is provided . the pulse generator circuit has an input adapted to receive an input electrical quantity and an output at which an output electrical quantity is made available . a transfer characteristic establishes a relationship between said input and said output electrical quantities . the pulse generator circuit is adapted to provide said output electrical quantity in the form of pulses having a predetermined shape , suitable to be used for uwb transmission . the transfer characteristic has substantially a same shape as that of said pulses . moreover , a uwb modulating system exploiting the novel pulse generator is proposed .