Improvement of Up-Converters Linearity for Ka-Band Operation

The application of a digital predistorter to the linearisation of a Ka-band mixer is presented herein. The general objective in the TX design is to get the best trade-off between linearity and costs. This require the most of the simplicity and possibly to take advantage from already existing devices (such as DSPs in modern digital transmitters) without perturbing their other functionalities. After a presentation of the problem and its constraints, we present the digital predistorter, which has been tested and debugged by means of IEEE-488 bus (GPIB) controllable instrumentation (EMA, electronic measuring automation) in order to finally consider its implementation on a fast new- generation FPGA device. Results show an increment of the linear zone in the up-converter AM-AM curve, of about 15 dB.