Digital Oscillators Noise Characteristics

Abstract

Digital modulated signals are a new modern element of transmitting devices that allows you to create high-quality complex signals. In this paper, the characteristics and capabilities of the AD9957 digital upconverter (DUC), which has a low level of phase noise, are studied. Positive results were obtained for creating signals that successfully meet the requirements for electromagnetic compatibility with the exception of out-of-band noise components. The report presents the results of measurements of the DUC AD9957 amplitude and phase noise levels. An increased level of amplitude noise was detected 20 dB higher than the level of phase noise. The results of measurements of noise levels of modern digital standard generators and for comparison – noise characteristics of analog quartz generators are presented. A significant excess of the amplitude noise level above the phase noise level was also found in the SMA 100 type generator (Rohde&Schwartz). This ratio is not observed in low-noise analog generators.