A Compact and Low Power 5–10 GHz Quadrature Local Oscillator for Cognitive Radio Applications

This paper presents the design and implementation of a compact and low power quadrature local oscillator (LO) for creating 13.3-20 GHz signal initially from a differentially tuned LC-VCO and then converting it to the desired 5-10 GHz with continuous frequency coverage. To accomplish such purpose, a 4-stage differential injection-locked ring oscillator (ILRO) is used subsequently to the latch-based divider to generate quadrature output phases without restricting 50% duty cycle from input signals as those of conventional divide-by-2 approaches. When implemented in a 65 nm general purpose CMOS IC technology, the integrated quadrature-phased LO consumes 22 mA of current at a 1 V supply and is able to exhibit the worst-case phase noise of -104 dBc/Hz at 1 MHz offset across the entire 5-10 GHz band for intended cognitive radio applications.