DCS1800/WCDMA adaptive voltage-controlled oscillator

The ever-increasing demands or telecom services that require a higher cellular capacity and a higher data rate have pushed the wireless industry towards the development of wide-band, third-generation wireless systems. On the other hand, as there is a number of applications that are comfortably served by second-generation systems, for maximum functionality, reduced cost and power consumption, the integration of both second and third generation cellular system should be the ultimate goal. Accordingly, an adaptive 2G/3G voltage-controlled oscillator (VCO) is described in this paper. For the DCS1800 operation, it achieves better than -133dBc/Hz phase noise at 3MHz offset from a 1.8GHz oscillating frequency at power consumption of 6 mW as well as better than -120dBc/Hz phase noise at 3 MHz offset from a 2.2GHz oscillating frequency while consuming 1.5mW for the WCDMA standard. By adapting the bias current, a phase-noise tuning range (PNTR) of more than 11dB can be realized, with more than a factor of four reductions in power consumption.