Apparatus (20) for generating a sine shaped output signal at an output (Sn, Sp). The apparatus (20) comprises a first transistors (M1) and a second transistor (M2) being arranged as differential pair (22). The differential pair (22) has two input nodes (Tp, Tn) allowing a triangular input signal (V.sub.in(t)) with a given amplitude (A) to be applied between a gate (Tp) of the first transistor (M1) and a gate (Tn) of the second transistor (M2). The differential pair (22) further comprises a node (X) where a source of the first transistor (M1) and a source of the second transistor (M2) is connected. The sine wave shaped signal is provided between a drain (Sp) of the first transistor (M1) and a drain (Sn) of the second transistor (M2). A current mirror (21) is employed for feeding a predefined tail current (I.sub.ss) into/out of the node (X) of said differential pair (22). The differential pair (22) allows the first transistor (M1) and the second transistor (M2) to be operated in the saturation region such that the sine wave shaped output signal (I.sub.o; V.sub.out) is a nonlinear function of the triangular input signal (V.sub.in(t)).