A process compensation technique for integrated VCO

A 2.576 GHz low phase-noise integrated VCO is presented, featuring a technique to compensate frequency drifts arising from process variation in PN varactors. PN varactors are used to achieve 10% tuning range, while MOS varactors are digitally switched to compensate for capacitance variations in the PN varactors. The designed VCO yields phase-noise as low as -98dBc/Hz at 100 kHz offset and guarantees 141 MHz of tuning range in the presence of manufacturing inaccuracies.