High-efficiency millimetre-wave silicon impatt oscillators

High-efficiency impatt devices and oscillators have been fabricated from epitaxially grown silicon for operation in the frequency range 40¿140 GHz. These devices have produced world state-of-the-art efficiencies and demonstrated the expected relative frequency insensitivity of silicon. Single drift devices have given efficiencies of approximately 8%; and double drift device efficiencies as high as 13.5% at 50 GHz and 12% at 90 GHz. Initial measurements show that the sideband phase noise levels follow a constant deviation law.