Design Of Digital Pre-Distortion Hardware Platform

At present, the wireless communication technology is developing rapidly, the requirement of communication system capacity is becoming more and more large. Modern wireless communication system has widely adopted high-order modulation mode, such as QAM, QPSK, etc., in order to achieve greater system capacity and higher spectrum efficiency. Higher order modulation method has higher spectrum efficiency, but it has the high peak power ratio, easily affected by the nonlinear distortion of power amplifier, it will cause the waste of resources and the improvement of operating costs. Among many of the power amplifier linearization technology, the realization of the digital pre-distortion technology is simple, low cost and good performance, and it has received the most attention and research, becoming a focus in the study of the current power amplifier linearization.Based on the requirements of broadband digital pre-distortion, refer to the TI design scheme of high speed digital pre-distortion platform. The high speed digital pre-distortion verification platform can be used for pre-distortion verification in joint with Xilinx V6FPGA development board. Employing the zero IF, the verification platform can support transmitting channel signal from frequency2300MHz to2400MHz and2600MHz to2700MHz, with the bandwidth of100MHZ, the output power of16dBm, and the ACPR of signal is less than-55dBc; Feedback channel centre frequency is at122.88MHz, using sampling rate of500MHz. At the same time this thesis solved the IQ imbalance appeared in the process of system debugging, the local oscillator leakage, and broadband signal frequency domain of the burr problem. Last, associated with Xilinx V6FPGA development board,16QAM modulation signal with50MHZ bandwidth is used for the pre-distortion performance test, the test results show that the measured power amplifier ACPR performance is improved about10db, proved the feasibility of the high-speed pre-distortion verification platform.High speed digital pre-distortion verification platform can be applied to LTE and LTE-A system with two frequency band (2.35GHz and2.65GHz), it can be used for power amplifier pre-distortion algorithm debugging and linear effect validation, which can effectively shorten the cycle of pre-distortion algorithm theory to practical application development.