Assemble A Ku-Band Frequency Synthesizer

摘要

Frequency synthesizers are an essential part of modern digital-microwave-radio (DMR) communications systems. With new ITU-R recommendations for DMR communications bands at 15, 18, 23, 38, and 55 GHz, frequency synthesizers are needed for use as local oscillators (LOs) for the frequency upconversion chores in transmitters and the frequency downconversion in receivers for a variety of different frequency architectures. The design of a Ku-band (14.4 to 15.5 GHz) frequency synthesizer offers practical benefits for several of these bands, since with multiplication by four it can be made to provide frequency coverage as high as 60 GHz. The programmable frequency synthesizer, which switches in 625-kHz steps and can be used with quadrature phase-shift-keying (QPSK) and quadrature-amplitude-modulation (QAM) transmission schemes, is a straightforward design that features low phase noise and reliable operation using commercially available oscillator and phase-lock-loop (PLL) integrated circuits (ICs).