Full digital phase noise measurement by using two reference oscillators and multichannel ADCs

It is realized that full digital phase noise measurement system which computes phase noise spectrum after sampling oscillator's signal using analog to digital converter directly. However, in these reports oscillator pairs are used; i.e. DUT oscillator and reference oscillator pairs are needed. These method needs low phase noise characteristics less than DUT oscillator for reference oscillator, or an oscillator of the same specification is required. On the other hand, in traditional (analog and digital mixed) phase noise measurement, it can measure the DUT's phase noise by using two reference oscillators with calculation of cross-correlation, even if the phase noise of the reference oscillator is greater than the DUT. However, there is no report that two reference oscillators are used in full digital phase noise measurement. In this paper we discuss about full digital phase noise measurement system using two reference oscillator. As a result, it was able to measure the DUT phase noise using two reference oscillators which phase noise were greater than DUT.