GaAs / Si MMICs Synthesized Upconverter for Broadband Tuners in Optical-Fiber CATV Systems

Abstract

A novel frequency-synthesized upconverter has been developed by implementing GaAs and Si MMICs, and applied to ultra broadband FM-FDM video tuners. The upconverter includes 3 chips of GaAs MMICs: a dualoutput voltage controlled oscillator (VCO), an interstage amplifier and a balanced mixer, as well as 2 chips of Si MMICs: a high speed prescaler and a frequency counter. The measured phase noise is -80 dBcIHz at 1 kHz offset and two-tone intermodulation intercept is +3 dBm. Implementing this upconverter into an FM video tuner, successful performance has been obtained as tuning bandwidth broader than 2 GHz and video weighted S/N ratio of +55 dB. This will possibly be the key device in future video distribution systems through optical fiber networks.