The invention relates to an electronic circuit comprising differential signal input means, a combining stage, a discriminating stage and differential signal output means. The discriminating stage comprises four transistors (Q8, Q9, Q10, Q11) each having first electrodes (83, 93, 103, 113) and second electrodes (81, 91, 101, 111) and a respective gate electrode (82, 92, 102, 112). The first electrodes of said four transistors are connected to a common node. The combining stage is arranged to convert differential input signals into gate signals applied to the gate electrodes of some of said four transistors respectively.