Ultra-low-power quadrature VCO for 2.4 GHz-band IEEE 802.15.4 standard

A fully integrated quadrature voltage-controlled oscillator (QVCO) for IEEE 802.15.4 transceivers is presented. The QVCO supports the 2.4 GHz unlicensed industrial, scientific and medical (ISM) band. The proposed QVCO generates 2.25-2.9 GHz covering 2.4 GHz transceivers. Quadrature coupling between the VCO cores is achieved using common source transistors which have their drains directly connected to the supply voltage. By using this structure, the effect of 1/f noise upconversion in the phase-noise performance could be reduced. The QVCO achieves a measured phase noise of -116.74 dBc/Hz at 1 MHz offset with a centre frequency of 2.5 GHz. The proposed QVCO consumes 0.55 mW from a 0.45 V supply voltage and is implemented in a standard 0.13 μm CMOS process with a core area of 0.315 mm².