Abstract
Phase noise measurement is a method for measuring short term stability of signal sources. There are commercial phase noise measurement systems on the market and manufacturers may use different measurement methods on their products. In this paper, the bilateral phase noise comparison results are presented. Same type of phase noise measurement system was used by each laboratory. Travelling standard of comparison has phase noise characteristics comparable to reference signal source of phase noise measurement system so three oscillator comparison method was used. The comparison was carried out at 10 MHz, 100 MHz, 1 GHz, 5 GHz, 10 GHz and 20 GHz carrier frequencies for 1 Hz, 10 Hz, 105 Hz, 1 kHz, 10 kHz, 100 kHz, 1 MHz, 10 MHz (except 10 MHz carrier) offset frequencies. Since each signal source which were used in the comparison has special low noise mode, 10 MHz Low-Noise, 100 MHz Low-Noise and 250 MHz Low-Noise carrier frequencies were also added to comparison. For carrier frequencies higher than 1.6 GHz, there are two options for phase noise measurements. The first one is to use low noise downconverter module and second one is to use second phase detector which has frequency range up to 26.5 GHz. To compare each method, normal and downconverter measurements were performed at 5 GHz, 10 GHz and 20 GHz carrier frequencies. While very close comparison results can be achieved for most of carrier and offset frequencies, relatively big differences were measured for others. All results are presented with calculated uncertainty values. The calculated uncertainty values vary from 2.31 dB up to 6.70 dB.