Patent ID: 7647028

Claim:
A method for internally calibrating a radio frequency (RF) transmitter, comprising: generating within a radio frequency (RF) transmitter a first set of test points at which an output of the RF transmitter is measured, wherein each member of the first set of test points resides along a perimeter of a square trajectory in an in-phase and quadrature phase signal space, a subgroup of the test points located at respective corners of the square trajectory; measuring the radio frequency output of the RF transmitter at the first set of test points; generating estimates of a phase imbalance and a DC offset in a quadrature dimension from the radio frequency output of the RF transmitter; applying the estimates of the phase imbalance and the DC offset in the quadrature dimension to a compensator; measuring the radio frequency output of the RF transmitter resulting from applying the estimates to the compensator at a second set of test points, the second set of test points being a subset of the first set of test points and including a single member from the subgroup of test points; calculating a gain imbalance resulting from measuring the radio frequency output of the RF transmitter resulting from applying the second set of test points; applying the gain imbalance to the compensator; measuring the radio frequency output of the RF transmitter resulting from applying the gain imbalance to the compensator; calculating a DC offset in an in-phase dimension from measuring the radio frequency output of the RF transmitter resulting from applying a third set of test points, the third set of test points being a subset of the first set of test points and a subset of the second set of test points; and compensating for the measured DC offset in the in-phase dimension.