| 摘要 |
<p>A system for digital-to-analog conversion and up-conversion (frequency multiplication) that reduces the distortion and attenuation caused by the sinc effect is described. The shape of the sinc function that gives rise to the sinc effect is altered in a manner such that the distortion produced by the sinc effect is reduced. The output of a digital-to-analog converter is provided with a return-to-zero (RTZ) output such that the digital-to-analog converter produces output pulses rather than output levels as would be expected from a conventional sample-and-hold output. The use of output pulses pushes the first null of the sinc function to a relatively higher frequency and thus the sinc function does not produce as much distortion in the harmonics of the sampled signal. Since the harmonics are less distorted, a bandpass filter or other filter can be used to extract harmonics of the sampled signal rather than the fundamental frequency. In this manner, the digital-to-analog converter and filter together provide digital-to-analog conversion and frequency multiplication (up-conversion).</p> |
