Temperature Compensated 2.45 GHz Ring Oscillator with Double Frequency Control

A 2.4 GHz voltage controlled oscillator (VCO) with double frequency control has been designed using a CMOS 0.28 mum process for use in frequency synthesizer and open loop FSK modulation circuit in multi-band IEEE 802.15.4 wireless personal area network (PAN) applications. This double control allows the VCO to maintain its center frequency and tuning range throughout -40degC to 120degC. Simulations and measurements show the sensitivity of the VCO center frequency has been reduced from 1300 ppm/degC to 73 ppm/degC, while a phase noise of -96 dBc/Hz @ 1MHz offset with a power consumption of 18 mW have been achieved.