Short wavelength comb-type capacitive transmission line for application to miniaturised on-chip passive components on MMIC

A short wavelength CCTL (comb-type capacitive transmission line) structure on MMIC has been developed for application to miniaturised on-chip passive components. Of all transmission line structures that have been reported to date, the CCTL structure shows the shortest guided wavelength. Using the CCTL structure, a highly miniaturised impedance transformer has been fabricated on GaAs MMIC. The impedance transformer shows good RF performances in a broad band from S- to X-band, and its size is 0.042 mm , which is 0.95% of the size of the conventional transformer on MMIC.