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US 7,808,356 B2Granted
Integrated high frequency BALUN and inductors
AssigneeTheta Microelectronics, Inc.
InventorYannis Papananos
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Abstract
Integrated high frequency balanced-to-unbalanced transformers and inductors suitable for operation in high frequencies, such as radio frequencies. Embodiments disclosed give consideration to issues related to the layout of the top and bottom inductors for the minimization of capacitive effects between layers. A displacement between the conductive paths of the top inductor and the bottom inductor is shown that provides for superior performance over prior art solutions.
Claims16
An on-chip four-metal layer balanced-to-unbalanced (BALUN) transformer having a symmetrical primary inductor, the BALUN transformer comprises:
- first winding conductive paths formed in a first metal layer having a plurality of winding segments;
- shunts formed in a second metal layer and electrically connecting the first metal layer winding segments at respective intersections, thereby forming a primary inductor, the primary inductor having a first port at a first end and a second port at a second end of the primary inductor;
- second winding conductive paths comprised of a plurality of winding segments formed in a third metal layer;
- shunts formed in a fourth metal layer electrically connecting the third metal layer winding segments at respective intersections to form a secondary inductor, the secondary inductor having a third port and a forth port symmetrically positioned at each end of the secondary inductor, and further having a center tap connection from a position at the middle of the secondary inductor as a fifth port;
- the primary inductor and the secondary inductor each being essentially symmetrical inductors;
- the second winding conductive paths being horizontally displaced from the first winding conductive path to reduce capacitive coupling between the primary inductor and the secondary inductor while maintaining a magnetic coupling between the first winding conductive path and the second winding conductive path.
3 more elements
An on-chip inductor comprising:
- a first clockwise winding conductive path formed in a first metal layer and a first counterclockwise winding conductive path formed in the first metal layer, the first clockwise winding conductive path and the first counterclockwise winding conductive path together defining a multiple turn top inductor, the first clockwise winding conductive path having a first port at one end of the first clockwise winding conductive path and a second port at the other end of the first clockwise winding conductive path, the first counterclockwise winding conductive path having a third port at one end of the first counterclockwise winding conductive path and a fourth port at the other end of the first counterclockwise winding conductive path, the first clockwise winding conductive path and the first counterclockwise winding conductive path having shunts in a second metal layer at points of crossover between the first clockwise winding conductive path and the first counterclockwise winding conductive path, the first clockwise winding conductive path and the first counterclockwise winding conductive path both winding inward towards the center of the top inductor;
- and,
- a second clockwise winding conductive path formed in a third metal layer and a second counterclockwise winding conductive path formed in the third metal layer, the second clockwise winding conductive path and the second counterclockwise winding conductive path together defining a multiple turn bottom inductor, the second clockwise winding conductive path having a fifth port at one end of the first clockwise winding conductive path and a sixth port at the other end of the second clockwise winding conductive path, the second counterclockwise winding conductive path having a seventh port at one end of the second counterclockwise winding conducting path and a eighth port at the other end of the second counterclockwise winding conductive path, the sixth port and the eighth port abutting to form a center tap of the inductor, the second clockwise winding conducting path and the second counterclockwise winding conductive path having shunts in a fourth metal layer at points of crossover between the second clockwise winding conductive path and the second counterclockwise winding conductive path, the second clockwise winding conductive path and the second counterclockwise winding conductive path both winding outward from the center of the bottom inductor;
- and
- shunts formed between the fourth port and the fifth port and shunts formed between the second port and the seventh port, such that the current flow is always in the same winding sense so the mutual inductance of the inductor is developed in favor of the overall spiral inductance;
- the conductive paths of the top inductor and the bottom inductor being horizontally displaced from each other to reduce capacitive coupling between the top inductor and the bottom inductor.
3 more elements
Dependencies are inferred from the claim text.