US 7,457,252 B2
Current imbalance compensation for magnetics in a wired data telecommunications network
Roger A. Karam, Mountain View, Calif. (US); and John F. Wakerly, Oakbrook Terrace, Ill. (US)
Assigned to Cisco Technology, Inc., San Jose, Calif. (US)
Filed on Nov. 03, 2004, as Appl. No. 10/981,202.
Prior Publication US 2006/0115007 A1, Jun. 01, 2006
This patent is subject to a terminal disclaimer.
Int. Cl. H04B 3/00 (2006.01)
U.S. Cl. 370—252  [370/200; 340/538; 375/258] 30 Claims
OG exemplary drawing
 
1. A power sourcing equipment (PSE) apparatus, comprising:
a first magnetic device having a primary winding and a secondary winding;
a coupler for receiving a pair of conductors, the coupler coupled to the secondary winding of the first magnetic device;
power sourcing circuitry coupled to apply a common mode inline power voltage signal to the secondary winding of the first magnetic device;
circuitry for detecting an effective current imbalance in the pair of conductors; and
circuitry for applying, responsive to the circuitry for detecting, a direct current bias to a circuit element comprising the coupler and the secondary winding of the first magnetic device in a magnitude and direction to compensate for the current imbalance, wherein the circuitry for applying is configured to utilize a third winding of the first magnetic device.