Symmetric 3D passive components for RF ICs application

This paper proposes novel 3-D symmetric RF passive components, including inductors, transformers, and baluns. Layout areas of these components are drastically reduced by means of stacked structure while the symmetry of input and output ports is also maintained. The area saving of 3-D inductor is up 70 %. The 1:1 transformer shows less than 0.1 % inductance mismatch in a 18 GHz range, and K is up to 0.87 at 17 GHz. The 3-D balun manifests less than 0.8 dB gain mismatch from 5.25 GHz to 6 GHz and phase error is about 4° at 5.25 GHz according to measurement results. All the components are fabricated in a 0.18 μm standard CMOS process.