GaN operation at 400GHz is the aim of a research project at US III-V firm TriQuint.
This follows the achievement of Ft>240GHz last year, reported by TriQuint at the 2011 GOMACTech conference in Florida.
240GHz operation came from Phase I of a US government research programme called NEXT (Nitride Electronic NeXt-Generation Technology) in which the firm is a contractor.
TriQuint, which is planning to make commercial devices based on NEXT results, has now been contracted to participate in the 18 month long Phase II, which will concentrate on increasing yield and pushing operating frequency to 400GHz.
"Devices developed under NEXT open-up applications for lower voltage GaN-based products which achieve power densities at least four times higher than GaAs devices," said TriQuint defence products v-p James Klein. "NEXT devices provide technology for substantially improving performance in applications like phased-array radar and communications."
There is also a Phase III, which will seek to extend the operating frequency to 500GHz with still higher yields, and reduced circuit size.
As well as high-frequency devices, NEXT also focuses on enhancement-depletion mode GaN mixed-signal devices, similar to those used in GaAs enhancement-depletion MMICs.
Separately, TriQuint is working on enhancement-mode power switching devices needed for dc-dc converters.