A SiGe wideband VCO and divider MMIC with low gain variation for multi-band systems at 2.4 and 5.8 GHz

A wideband LC voltage controlled oscillator (VCO) is presented in this work. Measurements show a wide relative tuning range of 37.6% from 4.57 GHz to 6.69 GHz with a tuning voltage from 0 to 3 V. Using an integrated divide-by-2 circuit, both the 2.4 GHz and 5.8 GHz ISM bands can be covered. A key feature is the low gain variation, which stays below 12.5 % up to 6GHz and below 33.3% for the whole tuning range. At 5.725 GHz, the phase noise at 1MHz offset was measured to -105dBc/Hz. The VCO core consumes 4mA of current from a 3V supply voltage. It is implemented using an IBM 180nm SiGe BiCMOS process and the core area amounts to 0.5mm×0.4 mm.