A planar capacitor includes, in part, a first metal line forming spiral-shaped loops around one of its end point, and a second metal line forming spiral-shaped loops between the loops of the first metal line. The first and second metal lines are coplanar, formed on an insulating layer, and form the first and second plates of the planar capacitor. The planar capacitor may be used to form a filter. Such a filter includes a first metal line forming first spiral-shaped loops, a second metal line forming second spiral-shaped loops, and a third metal line—coplanar with the first and second metal lines—forming loops between the loops of the first and second metal lines. The filter further includes a first inductor coupled between the first and third metal lines, and a second inductor coupled between the second and third metal lines.