A method and apparatus for a method of calibrating a transmit digital to analog converter full-scale current. The method comprises generating a tuned reference current and then calibrating the tuned reference current to a selected value in order to produce a predetermined current value. The calibration further comprises dividing a reference voltage input over a resistor string. A band gap current is then generated using the divided reference voltage input. A tuned current output is then produced from a current steering digital to analog converter with the tuned output current stored in a register. The reference current for the transmit DAC is then generated based on the stored tuned output current.