A fully integrated 28nm Bluetooth Low-Energy transmitter with 36% system efficiency at 3dBm

We propose a new transmitter (TX) architecture for ultra-low power radios. An all-digital PLL employs a digitally controlled oscillator with switching current sources to reduce supply voltage and power without sacrificing its phase noise and startup margins. It also reduces 1/f noise allowing the ADPLL, after settling, to reduce its sampling rate or shut it off entirely during direct DCO data modulation. The switching power amplifier integrates its matching network while operating in class-E/F₂ to maximally enhance its efficiency. The transmitter is realized in 28nm CMOS and satisfies all metal density and other manufacturing rules. It consumes 3.6 mW/5.5mW while delivering 0dBm/3 dBm RF power in Bluetooth Low-Energy.