Inverse Design Techniques for Optimizing Passive Lumped Networks

The recent advancements in Microwave Integrated Circuits (MICs) have demonstrated that an interdigital capacitor (IDCap) can be designed to achieve a significantly enhanced quality factor to bandwidth ratio when compared to a lumped capacitor (N.L.K. Ngugen, et al., “A 1-160 GHz InP distributed amplifier using 3-D interdigital capacitors,” IEEE Microw. Wirel. Compon. Lett., May 2020). In this work, the IDCap was designed to mimic the impedance response of a lumped capacitor across the frequency band of 230− 240 MHz. Various global and local optimization techniques, including the genetic algorithm (GA), mixedinteger sequential quadratic programming (MISAP), and gradient descent (GD), were employed to attain an optimal IDCap design.