A low cost, high performance PLDRO for a 28 GHz LMDS system

LMDS system in the band 28-31 GHz using 64QAM as modulation scheme requires local oscillators whose phase noise, once filtered by the demodulator, must be low enough so as not to produce errors or degrade the fade margin of the link. In the last two years, a number of papers have dealt on the quantification of the LO phase noise requirements as a function of the modulation scheme and required service quality. This paper, on the other had, is focussed on the design aspects of a essentially low-cost phase locked dielectric resonator oscillator (PLDRO) for a customer premises equipment (CPE) that meet the required performance. This PLDRO is locked by means of a sampling phase detector (SPD). This approach avoids the added phase noise present in structures based on frequency dividers. A comparison of these two approaches in terms of performance and cost are also presented.