Pi Coil: A New Element for Bandwidth Extension

This brief presents a new passive element called Pi coil for bandwidth extension. Its transfer function and detailed design tables are given. Based on ideal elements, the proposed Pi coil can achieve the largest bandwidth extension ratio compared to its counterpart, i.e., T coil, and other similar bandwidth-enhancing techniques. In addition, the input return loss (S11) is much improved by using this technique. On-chip implementation methods of the T coil and the Pi coil are also investigated in this brief.