High efficient, high linearity transmitter for microwave digital radios

This paper summarizes the design and architecture of the transmitter, which is used in the product of Truepoint 6000 introduced by Harris Stratex Networks recently. The Transmitter includes the adaptive pre-distortion, a dual-loop RF synthesizer, programmable bias control and many other design features. The system shows a minimum 6dB improvement of IM3 over temperature, over frequency range, over power dynamic range and over various modulations and capacities. The baud rate covers from 3.5MHz to 40MHz. It demonstrates the first of this kind of adaptive pre-distortion feature in a commercialized microwave digital system. The dual loop synthesizer architecture gives advantages such as very low phase noise, low spurious, high susceptibility for micro-phonics and phase hits. The system test shows great results for the radio´s overall performance including regulatory mask and micro-phonic requirement.