A 0.059-mm2 10.8-mW local oscillator for GSM systems in 65-nm CMOS

A GSM-compliant local oscillator consuming a tiny die area of only 0.059 mm² and drawing 9 mA from a 1.2 V supply has been designed in a 65-nm CMOS process using thin-oxide devices only. The system is made of a 13 to 15 GHz LC VCO followed by a divide-by-four injection-locked frequency divider. The divider employs a ring oscillator-based topology leading to a two octave locking range with limited area and power consumption. The phase noise at the output of the system is less than -133 dBc/Hz at 3 MHz offset over the tuning range.