High performance offset synthesizer

Broadband portable communications equipment demands frequency synthesizers with low phase noise, Hz resolution, fast tuning, low size and low power consumption. This paper describes the development of a high performance synthesizer for a portable transceiver able to cover wide-band width fast tuning (17μs), Hz resolution, low phase noise (-100 dBc @ 10 KHz), low harmonics level (-78dBc), together with low size and power consumption. The architecture of the synthesizer is based on the use of several VCOs mixed with an offset frequency and combined with a low phase noise direct digital synthesizers (DDS). This configuration can replace broadband YIG oscillators based synthesizers with much better tuning speed, equivalent phase noise and important size and power consumption reduction.