An electronic device used as a non-linear capacitor.

An electronic device which includes first, second and third conductor layers respectively arranged as the source 10, drain 11 and gate 9 electrodes of a field effect transistor (FET). The third layer is capacitively coupled with both the first and second conductor layers. An alternating voltage is applied across the gate conductor layer and either of the source and drain conductor layers, whilst leaving the other of the source and drain conductor layers at a floating potential. Preferably pairs of conductor layers are used (fig. 5a), each of the pairs consisting of a drain and source conductor layer.