Direct Digital Synthesizer at the Microwave Spectroscopy

Abstract

The results of investigation of the possibi- lity of application of a direct digital synthesizer (DDS) as a reference source in a millimeter-wave spectrometer are shown. It is also shown that combining the direct digital synthesis with the narrow-band phase lock loop will allow to reach a large factor of frequency multiplication (up to 600) of the DDS output signal. The new synthesizer is successfully applied as a reference source for a millimeter-wave spectrometer which is intended for investigation of rotational spectra of molecules. The spectral purity was estimated by molecular spectra records and had shown to be not worth than that of the synthesizer of direct analog synthesis. At the same time, a new synthesizer has much more smaller size, weight, and power consumption.