ABSTRACT
Recently, terahertz (THz) and sub-terahertz (sub-THz) oscillators have received an increasingly intensified attraction from both academic research and the consumer electronics market. As the oscillating frequency approaches the fmax of the advanced silicon/III–V semiconductor processes, achieving high power efficiency while maintaining a decent output power is essential and challenging for THz oscillators. And with the electrical wavelength scaling down, more distributed effects as well as high-frequency parasitic make the “active” device itself no longer seen as a “lump” device but more as a mixed model with EM and semiconductor device effects. Similarly, the boundary of the so-called “active core” and “passive network” which is clearly defined in low frequencies becomes obscure as frequency increases. Hence, there is a need to have a systematic design methodology, which synthesizes the individual terms, i.e., “active transistor,” “active core,” and “passive network,” together to have a global optimization. In this chapter, we share a holistic optimization method of designing a THz oscillator with a design flow 224provided for optimization iterations. A design example is followed to demonstrate both good power efficiency and high output power for a sub-THz oscillator by using such a methodology.
