Ultra-wide-band coplanar waveguide based impedance transformer using slow-wave electrodes

Abstract

This paper presents a new type of broadband impedance transformer loaded with capacitive fins (ITF) suitable for use in the frequency range 10 GHz to 70 GHz. Compared with conventional, unloaded, tapered impedance transformers, these ITF structures extend the impedance matching range and the operating bandwidth for the same amount of on-chip realestate. We have designed ITFs capable of impedance matching resistive loads from ~ 10 Ω to ~ 229 Ω, on a 650 μm thick GaAs substrate over about a 60 GHz bandwidth. Design examples are used to demonstrate the flexibility of these ITF structures.Broadband impedance transformer, slow-wave electrode theory, capacitive loading fins, coplanar waveguide.