A 0.65V 2.5GHz Fractional-N Frequency Synthesizer in 90nm CMOS

Abstract

A 2.5GHz fractional-N synthesizer is realized in a digital 90nm CMOS technology. The RF dividers operate at 0.65V while the remainder of the PLL operates at 0.5V; no special devices or voltage boosting is used to achieve the 0.5V operation. The synthesizable range covers 2.4 to 2.6GHz with a phase noise of -55dBc/Hz in band and -120dBc/Hz at a 3MHz offset. The synthesizer dissipates 7mW and occupies 0.14mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .