T-coil design with optimized magnetic coupling coefficient for improving bandwidth extension

摘要

For a T-coil IC, a first inductor core is on an M_x layer and has n turns (n≥15/8). The first inductor core has a first-inductor-core-first end and a first-inductor-core-second end. A second inductor core is on an M_x-2 layer and has n turns. The second inductor core has a second-inductor-core-first end and a second-inductor-core-second end. The first-inductor-core-second end is connected to the second-inductor-core-first end by a via stack between the M_x and M_x-2 layers. A center tap is on an M_x-1 layer. The center tap is connected to the second inductor core at a node of the second inductor core. A first inductor is formed by the first inductor core between the first-inductor-core-first end and the first-inductor-core-second end and by the second inductor core between the second-inductor-core-first end and the node. A second inductor is formed by the second inductor core between the node and the second-inductor-core-second end.