New high resolution and low distortion coherent sweep oscillators

作者：Al Ibrahim M^*; Al Olofi M

来源：Electrical Engineering, 2010, 92(1): 27-34.

DOI：10.1007/s00202-010-0156-4

• Coherent digital sweep oscillator
• Piecewise parabolic interpolation
• Look-up-table
• Spectral performance
• Optimized coefficients

In this paper, a new coherent digital sweep oscillator is proposed and its performance is evaluated. The proposed oscillator employs piecewise parabolic interpolation to decrease the look-up-table (LUT) size and system complexity while maintaining excellent spectral performance. The interpolation coefficients are predetermined in such a way that optimizes the spectral performance of the oscillator and are stored in the LUT. The interpolator generates the sample values of the sine wave using the optimized predetermined interpolation coefficients from the calculated phase. Hence, a few reference sample values and the optimized coefficients are stored in a small LUT. The complexity of the oscillator structure is decreased by eliminating one of the two multipliers needed to implement the interpolator. The proposed oscillator is simulated using optimized coefficients for different number of quarter sine wave segments. A comparison between the new oscillator and previously reported sweep oscillators indicates its superior performance and hardware efficiency. The ratio of the LUT size needed for the new oscillator is found to be 1:128 when compared with that of Pedersen oscillator with 12-bit address lines and 14-bit word length.

• 出版日期2010-6