Effect of phase non-linearity in phase noise sensitivity of discriminator based measurement

Some critical investigations on the phase non-linearity in Delay Line Discriminator (DLD) are reported in this article to increase phase noise measurement sensitivity. A critical issue of phase non-linearity in wide-band phase noise measurement is studied during practical system realization. Substrate attachment process for longer delay line printed circuit board (PCB) over metallic housing has been proposed for DLD based phase noise measurement system development in details. Conventional lead or lead free reflow methods for PBC attachment over metal base have void formation issue for large surface area. Phase nonlinearity effect has been analyzed for its importance in measurement sensitivity. Vapour Phase Assembly (VPA) at 250 °C is suggested in case of long track PCBs for avoidance of any phase mismatch. Finally, non-linearity result of conventional reflow are compared with VPA substrate attachment. Examination of non-linearity reduction within ± 20° for improving measurement sensitivity is applicable for narrow and wideband phase noise analyzers.