Based on trigonometric identities, Sunderland technique is a effective compression algorithm for mapping from phase to sine amplitude in ROM-based direct digital frequency synthesizers(DDS)design. A modification based on Taylor-series linear interpolation method was proposed to provide additional improvements in compression efficiency. Their effect on distortion and trade-offs were investigated, and spurious were identified by using fast Fourier transform algorithm (FFT). A computer program was created to simulate and optimize the effects of the memory compression and algorithmic techniques on the output spectrum of the DDS with the help of matlab computing tool. The subjected multiplierless architecture was then implemented in a Xilinx’s field programmable gate array (FPGA). Simulation results show that the proposed techniques is effective, and the digital output of the designed DDS which using this compression technique has the worst case spurious about -90?dB. A 80?MHz DDS was developed and used successfully in a actual projects of a GPS signal simulator system.
Zhu Yuhong, Zhang Qishan, Chang Qin.Design of a algorithm of mapping from phase to sine amplitude in DDS of a GPS signal simulator system[J] JOURNAL OF BEIJING UNIVERSITY OF AERONAUTICS AND A, 2005,V31(12): 1308-1311
Sunderland D A, Strauch R A, Wharfield S S, et al. COMS/SOS frequency synthesizer LSI circuit for spread spectrum communications[J].IEEE Journal of Solid-State Circuits.1984,19(4):497-506
Nicholas H T, Samueli H, Kim B. The optimization of direct digital frequency synthesizer performance in the presence of finite word length effects . Proceedings of the 42nd Annual Freq Control Symp . Monmouth NJ:USERACOM, Ft,1988.357~363
Bellaouar A, O'brecht M S, Fahim A M. Low-power direct digital frequency synthesis for wireless communications[J].IEEE Journal of Solid-State Circuits.2000,35(3):385-390
Sodagar A M, Lahiji G R. Mapping from phase to sine-amplitude in direct digital frequency synthesizers using parabolic approximation[J].IEEE Trans Circuits Syst .2000,47:1452-1457
½ ��,�� ��,������,��. ʮ��ͨ��GPS�źŷ����������о�[J].�������պ����ѧѧ��.2003,29(4):331-334
Kroupa V F. Synthesis techniquues . Derect Digital Frequency Synthesizers, A Selected Reprint Volume . New York:Institate of Electical and Electronics Engineers,1999.3~13