Patent ID: 7526256

Claim:
A communication system, comprising: a receiver module operable to receive an inbound radio frequency (RF) signal; a transmitter module operable to generate an outbound RF signal; and an on-chip multiple tap transformer balun for coupling to an antenna, the receiver module and the transmitter module, the transformer balun being operable to receive the inbound RF signal from the antenna and further operable to provide the outbound RF signal to the antenna; wherein the transformer balun comprises: a first winding on a first layer of an integrated circuit, wherein the first winding is a primary winding of the transformer balun for coupling to the antenna for a single-ended operation; a first portion of a second winding on a second layer of the integrated circuit in which the second winding is a secondary winding of the transformer balun, wherein a first node of the first portion of the second winding is operably coupled to a first leg of a first differential signal path, wherein a second node of the first portion of the second winding is operably coupled to a reference potential, and wherein a tap of the first portion of the second winding is operably coupled to a first leg of a second differential signal path; and a second portion of the second winding on the second layer, wherein a first node of the second portion of the second winding is operably coupled to a second leg of the first differential signal path, wherein a second node of the second portion of the second winding is operably coupled to the reference potential, wherein a tap of the second portion of the second winding is operably coupled to a second leg of the second differential signal path, wherein the second portion of the second winding is substantially symmetrical to the first portion of the second winding, and wherein the tap of the first portion of the second winding is substantially symmetrical to the tap of the second portion of the second winding; wherein the first differential signal path couples to the receiver and transmitter modules to transfer RF signals of a first range of frequencies and the second differential signal path couples to the receiver and transmitter modules to transfer RF signals of a second range of frequencies different from the first range of frequencies, and wherein the second windings are selected for operation at the first range of frequencies and locations of the taps are selected for operation at the second range of frequencies.