Patent ID: 8219032

Claim:
A method for estimating distortion in a transmitter circuit in a wireless communications system, the method comprising: in a single chip comprising a radio frequency (RF) transmitter and an RF receiver, generating an RF output signal at an output of one or more power amplifiers in said RF transmitter in response to a generated one or more input signals; generating one or more feedback signals by performing a frequency downconversion operation on said generated RF output signal within a corresponding one or more feedback mixer circuits in said single chip; and selectively inserting said generated one or more feedback signals at a corresponding one or more insertion points in said RF receiver utilizing one or more switches according to one of a normal operating mode and a calibration mode, wherein each of said corresponding one or more insertion points is between a corresponding mixer circuit in said RF receiver and a corresponding one or more circuits within said single chip that generate a baseband signal based on a corresponding one of said generated one or more feedback signals, and wherein said corresponding mixer circuit in said RF receiver is separate from said one or more feedback mixer circuits, and wherein selectively inserting according to said calibration mode comprises configuring a closed feedback loop comprising said RF transmitter and a portion of said RF receiver defined by said one or more insertion points.