A zero crossing avoidance predistortion technique for polar transmitters

This paper presents a predistortion technique that facilitates analogue signal reconstruction in polar transmitters. The predistortion consists to prevent the instantaneous amplitude to go down or very close to zero for complex modulations where this can normally happen. The technique called zero crossing avoidance was successfully applied to the 8PSK modulation of the Bluetooth standard. Its benefit for decreasing spectral leakage into adjacent channels and reducing the peak frequency deviation of the modulation are demonstrated.