Patent ID: 6998938
Filing Date: 2006-02-14
Classification: H03H,H05K

Abstract:
1. A lumped-element low-pass filter formed in a multi-layered substrate comprising: a first inductor; a second inductor electrically connected to the first inductor in series at one end, wherein the first and second inductors are spiral in shape and the orientations of the first inductor and the second inductor are of opposite sense such that a mutual inductance between the first inductor and the second inductor is negative and equals a first value; a first capacitor shunt-connected to the first inductor; a second capacitor shunt-connected to the second inductor; and a third capacitor having a first end electrically connected to ground and a second end electrically connected to the end of the second inductor at which the second inductor in connected to the first inductor; wherein the first inductor is formed on a fourth layer of the multi-layered substrate, the second inductor is formed on a third layer of the multi-layered substrate and is electrically connected to the first inductor in series through a first via penetrating the substrate, the first capacitor comprises two plates formed on a fifth layer and a sixth layer of the multi-layered substrate, in which the plate formed on the fifth layer is connected to the first inductor through a second via penetrating the substrate and the plate formed on the sixth layer is connected to the first via, the second capacitor comprises two plates formed on a first layer and a second layer of the multi-layered substrate, in which the plate formed on the second layer is connected to the second inductor through a third via penetrating the substrate and the plate formed on the first layer is connected to the first via, and the third capacitor is formed between the first layer and a ground layer of the multi-layered substrate, in which the first layer is next to the ground layer.