Radio Frequency Integrated Circuit (RFIC) research at CVEST focusses on the modeling, design, fabrication and characterization of on-chip RF components. The aim is to provide low-cost, low-power and high yield designs of various RF components used extensively in communication devices. New analytical and modeling techniques are also developed to improve the understanding of RF circuits and the underlying principles. Main areas of research in this group are:
On-chip RF Inductors
Inductors are used in RFICs for impedance matching, as a tuned load, series feedback element etc. They play a limiting role in RFICs because of the large area they accupy, lower Q-factor, associated noise and parasitic coupling. Our group has demonstrated improvement in the inductor Q-factor and frequency response by incorporating domain-patterned Permalloy of various thicknesses on top of inductors. The fabricated inductor is shown in Fig. 1. Varying the shape, size and thickness of the Permalloy gives about 200% peak improvement in inductance and 700% peak improvement in Q-factor.
Micromagnetic simulations with Object Oriented Micro-Magnetic Framework (OOMMF) are performed to determine the domain patterns, confirming the influence of shape and size induced domain patterns on the performance of inductors. One such simulated domain pattern indicating a double domain structure in the middle and closure domains at the end is shown in Fig. 2