A wideband subharmonically injection‐locked frequency synthesizer for LMDS

Abstract

AbstractA 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 30: 310–312, 2001.