Patent ID: 7443268

Claim:
A bandpass filter, comprising: an input node; an output node; a first substrate with a first conductive plate forming a first RF ground plane; a second substrate, comprising: a first serpentine conductive trace forming a first inductor and coupled to the input node; a second conductive plate coupled to the first serpentine conductive trace and substantially overlapping the first conductive plate; a second serpentine conductive trace forming a second inductor and coupled to the second conductive plate; a third serpentine conductive trace forming a third inductor; a third conductive plate, substantially overlapping the first conductive plate; a fourth serpentine conductive trace forming a fourth inductor and coupled to the third conductive plate; and a fifth serpentine conductive trace forming a fifth inductor and coupled to the third conductive plate and the output node; a third substrate, comprising: a fourth conductive plate, substantially overlapping the second conductive plate and coupled to the second inductor; and a fifth conductive plate, substantially overlapping the third conductive plate and coupled to the fourth conductive plate and the fourth inductor; and a fourth substrate with a sixth conductive plate to form a second RF ground plane, the fourth and fifth conductive plates substantially overlapping the sixth conductive plate; wherein the first, third and fifth inductors are coupled to one of the first and second RF ground planes.