A wideband subharmonically injection-locked frequency synthesizer for LMDS

A low-cost wideband subharmonically injection-locked frequency synthesizer for local multipoint distribution system (LMDS) down-converter applications is introduced in this letter. This synthesizer consists of a 2.0 GHz PLL synthesizer, and is a general-purpose bipolar transistor VCO at 5.8 GHz. The 5.8 GHz VCO is not only subharmonically injection locked by a 2.0 GHz PLL synthesizer, but also, the varactor diode's voltage is adaptively controlled by the 2.0 GHz PLL controlling voltage via a suitable converter at the same time. In this way, real-time wideband locking can be attained. When third subharmonically injection locked, the output power of the synthesizer is more than 7.5 dBm, with a bandwidth of more than 25%. At 5.8 GHz, the power is 8.5 dBm, and the phase noise is - 93 dBc / Hz at an offset frequency of 100 kHz. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett.