Objective: Design, manufacture and test an RF pre-distorter based on a single-chip, for High Power Amplifiers, that is able to linearize in a closed-loop operation telecommunication multi-carrier signals
Description: The DC-to-RF efficiency of High Power Amplifiers (HPAs) is currently the main contributor to the power consumption of a spacecraft. This equipment is responsible for consuming >70% of the overall DC power available in bent-pipe architectures for broadcasting satellites.
To improve the scenario, analogue pre-distortion techniques are currently used in order to linearize the HPA. This analogue linearisation allows for an increase of the overall DC-to-RF efficiency since the HPA can be operated closer to saturation.
Nevertheless,the linearisation function is tuned for one single configuration of the HPA and for static conditions (i.e. temperature, RF output power, etc.). In addition, the capability of linearising HPAs presenting memory effects or with non-uniform traffic demands, is verylimited when using analogue linearisers.
Closed-loop RF pre-distortion techniques are more suitable for this variable scenario, where the lineariser uses the HPA output signal to determine the nonlinear characteristics of the HPA and adapts the linearisation technique as a function of the conditions and signal to be transmitted (i.e. modulation scheme, temperature of the HPA, level of back-off, bias point, etc.). This technique allows a dynamically optimised transfer function and enhance the overall HPA efficiency.
The US has a commercial product (Maxim SC 1894) already available while no product yet exists in Europe.
The work logic shall be as follows: