Abstract: A method and an apparatus are described for constructing a compact inductive-capacitive circuit, using a spiral inductor of more than one turn, plus a capacitive plate. This method includes duplicating the layout of the spiral, and then offsetting the duplicate so that the trace pattern of the spiral overlaps its duplicate at an insulating distance away, with the duplicate as an underlying capacitive plate. The plate's trace pattern includes at least one gap, plus an extension of its trace to span the region under the terminals of the spiral inductor. For the case where the spiral inductor has more than one turn—plus an underpass—the capacitive plate may also have more than one turn and may also have an underpass. The resulting pair of underpasses may be either overlapping or nonoverlapping. If overlapping, the full circuit requires at least four metal layers, and at least three if the underpasses are nonoverlapping.

Abstract: A method and an apparatus are described for constructing a compact inductive-capacitive circuit, using a spiral inductor of more than one turn, plus a capacitive plate. This method includes duplicating the layout of the spiral, and then offsetting the duplicate so that the trace pattern of the spiral overlaps its duplicate at an insulating distance away, with the duplicate as an underlying capacitive plate. The plate's trace pattern includes at least one gap, plus an extension of its trace to span the region under the terminals of the spiral inductor. For the case where the spiral inductor has more than one turn—plus an underpass—the capacitive plate may also have more than one turn and may also have an underpass. The resulting pair of underpasses may be either overlapping or nonoverlapping. If overlapping, the full circuit requires at least four metal layers, and at least three if the underpasses are nonoverlapping.