Millimetre wave VCOs with wide electronic tuning range for synthesised radios

A series of new and very compact local oscillators for point-to-multipoint (PMP) and point-to-point (PtP) radio link systems has been developed in the 26 GHz to 36 GHz frequency range. The oscillators mainly consist of a GaAs-pHEMT microwave monolithic integrated circuit (MMIC) and a planar ring resonator (RR). Three MMICs have been designed to cover the whole frequency range. The ring resonator operates at harmonic frequencies. An innovative fully automated active laser-trimming procedure is used to adjust the centre frequency, the varactor tuning sensitivity, the electronic tuning range, respectively, and the electrical line length between the MMIC and the ring resonator. The laser tuneable frequency range is larger than 10% without any significant deterioration of the oscillator´s characteristics. The maximum electronic tuning range can be adjusted by laser-trimming to values of more than 2.5% of the centre frequency. A typical single-band phase noise value of approx. -108 dBc/Hz is achieved at an offset frequency of 1MHz. The temperature drift of the oscillator frequency is typ. 9 ppm/K.