RF ICs at millimeter waves and beyond

As IC process technologies continue to scale, it is natural to consider when or whether ICs might practically bridge the "terahertz gap". Scaling trends suggest that the available output power of individual devices may be insufficient for many applications, even if available power gain suffices. Free-space (quasi-optical) power combining enables significant improvements. Novel devices that exploit velocity modulation can further extend practically accessible frequencies or bandwidths by an order of magnitude or more. Suitable detectors exist, and so terahertz integrated circuits are almost certainly inevitable.