Jumping the Gunn

Dr Heribert Eisele has fi rmly held the belief for many years that ¿ as has happened with Si MOSFETs ¿ the frequency limits of InP Gunn devices, which belong to the group of negative differential resistance devices, could be pushed much further and that their full potential had not yet been realised. Forming part of the resonant circuit in an oscillator which operates at 160 GHz, the Gunn device produces a third-harmonic at 480 GHz, and it is this signal that Eisele has successfully enhanced and extracted using waveguide transitions and spacers. As Gunn devices operate at much lower current densities than the transistors in power amplifi ers, they will be much more reliable and the oscillator can also be reduced in size to a few cm³ making it compact as well.