Australian Journal of Basic and Applied Sciences, 4(10): 5028-5037, 2010 ISSN 1991-8178 © 2010, INSInet Publication FPGA Implementation of the Complex Division in Digital Predistortion Linearizer Somayeh Mohammady, Pooria Varahram, Roslina Sidek, Mohd Nizar Hamidon, Nasri Sulaiman Department of Electronics and Electrical Engineering, Universty Putra Malaysia, 43400, Serdang Malaysia Abstract: Since division is not a standard operation for DSP processors and because it can be implemented in several different ways, there is no specific algorithm clearly to choose. It all depends on the requirements, such as accuracy, size and speed. A few suitable algorithms should be selected and implemented in VHDL for evaluation. The implementation is expected to be a part of an existing baseband processor and should be able to handle the high speed requirements while keeping the size down. Here we implement complex division based on Newton Raphson method. This divider will be used in the Digital Predistortion for adaptation of the power amplifiers. Based on the requirements of the input signal, the divider that is implemented here has different features and makes it suitable for digital communication where we deal with complex values. The results of simulation show improvement in hardware resources as compare to other methods. Key words: Division, DSP, VHDL, Digital Predistortion INTRODUCTION In baseband processing for radio communication there is a need to manipulate complex numbers in various ways in order to decode the transmitted data from the digitized radio waves. One of the effects that the receiver has to take into account is fading. The radio waves from the transmitter will bounce on many different surfaces in many directions before ending up at the receiver. There is a resulting time shift between the signals from the different paths and when they arrive at the antenna they will be added together. The result of this is that different parts of the frequency spectrum are attenuated differently. One way to compensate for this is to get an estimate of the attenuation and amplify the frequencies with low amplitude. The magnitude of the amplification is equal to the inverse of the estimated attenuation. The high data rates of the communication put a demand of high speed on the inversion. Therefore it needs to be implemented in hardware. The computer applications include operations such as addition, multiplication, and division but commonly implementation of division has not been received high priority in designing systems but ignoring it can cause significant system performance degradation. In this paper, the implementation of complex division function in Matlab software is presented. The application of this function is in baseband radio communication systems where radio waves need to be processed and decoded in digital processors. One of the results will be to overcome the problem of multi path signals and fading effects. So in next section complex divider implementation is described which uses a few equations in its algorithm that are presented later on. Since division is not a standard operation for DSP processors and because it can be implemented in several different ways, there is no specific algorithm to choose. It all depends on the requirements one have on its properties, such as accuracy, size and speed. A few suitable algorithms should be selected and implemented in VHDL for evaluation. The implementation is expected to be a part of an existing baseband processor and should be able to handle the high speed requirements while keeping the size down. There are two ways to perform a division with logical circuitry. The way, which is used by the Xilinx CoreLib is to calculate each bit exactly. Alternatively, an approximation method can be used. Unlike the exact calculation, where the hardware effort is directly proportional to the bit-width, by using an approximation method the hardware effort is directly proportional to the number of iterations. A Simulink is used to optimize the algorithm and to analyze the error. The complex division that is designed here will be applied in digital predistortion technique that is introduced in (Varahram, P., 2009). Corresponding Author: Somayeh Mohammady,Department of Electronics and Electrical Engineering, Universty Putra Malaysia, 43400, Serdang Malaysia 5028