Temperature Compensated 2.45 GHz Ring Oscillator with Double Frequency Control

A 2.4GHz Voltage Controlled Oscillator (VCO) with double frequency control has been designed using a CMOS 0.28μm 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 -40°C to 120°C. Simulations and measurements show the sensitivity of the VCO center frequency has been reduced from 1300ppm/°C to 73ppm/°C, while a phase noise of -96dBc/Hz @ 1MHz offset with a power consumption of 18mW have been achieved.