Medium power oscillator design for 1.8 GHz band using large signal S-parameter analysis

The design and implementation of an 1.8 GHz voltage controlled oscillator are presented in this paper. The oscillator can provide 0.3 W output power at 6 V supply. With the simplicity in circuit construction, the component count can be largely reduced while comparing with the traditional multiple stage approach. For a convenient way to extract the design information from the completed circuit, the external feedback path of the oscillator is broken down so that the oscillator circuit was reformed to be a open-loop non-oscillating two-port network. The characteristic of the network can be analyzed easily. Significant predictions of the oscillators performances drawn from such analysis are described.