Combiner circuit for dual band voltage controlled oscillators

摘要

Dual band voltage controlled oscillators (VCOs) incorporate a combiner circuit with a single output operable at two widely separated frequency bands such as 900 MHz and 1.8 GHz, for example. The combiner circuit includes a duplexer used as a combiner on the outputs of the VCOs. The duplexer can be realized in transmission line or inductor configurations. The use of the duplexer improves spurious performance and phase noise by more than 10 dB between the two operating frequency bands and supplies band rejection at the non-operating frequency.