Low-power quadrature generators for body area network applications

Abstract

This paper presents different alternatives for the implementation of low-power monolithic oscillators for wireless body area networks and describes the design of two quadrature generators operating in the 2.4-GHz frequency range. Both implementations have been designed in a 90-nm Complementary Metal-Oxide Semiconductor (CMOS) technology and operate at 1 V of supply voltage. The first architecture uses a voltage-controlled oscillator (VCO) running at twice the desired output frequency followed by a divider-by-2 circuit. It experimentally consumes 335 μW and achieves a phase noise of −110.2 dBc/Hz at 1 MHz. The second architecture is a quadrature VCO that uses reinforced concrete phase shifters in the coupling path for phase noise improvement. Its power consumption is only 210 μW, and it obtains a phase noise of −111.9 dBc/Hz at 1 MHz.