This paper proposes an ultra-low-voltage (ULV) fractional-N all-digital PLL (ADPLL) powered from a single 0.5-V supply. While its digitally controlled oscillator (DCO) runs directly at 0.5 V, an internal switched-capacitor dc-dc converter ``doubles'' the supply voltage to all the digital circuitry and particularly regulates the time-to-digital converter (TDC) supply to stabilize its resolution, thus maintaining fixed in-band phase noise (PN) across process, voltage, and temperature (PVT). The ADPLL supports a two-point modulation and forms a Bluetooth low-energy (BLE) transmitter realized in 28-nm CMOS. It maintains in-band PN of -106 dBc/Hz [figure of merit (FoM) of -239.2 dB] and rms jitter of 0.86 ps while dissipating only 1.6 mW at 40-MHz reference. The power consumption reduces to 0.8 mW during the BLE transmission when the DCO switches to open loop.

Original languageEnglish
Pages (from-to)2572-2583
Number of pages12
JournalIEEE Journal of Solid State Circuits
Issue number9
Publication statusPublished - 2018

    Research areas

  • All-digital PLL (ADPLL), and temperature (PVT) insensitive, Bluetooth, Bluetooth low energy (BLE), Calibration, Clocks, Delays, digitally controlled oscillator (DCO), Internet of Things (IoT), Oscillators, Phase locked loops, process, regulator, switched-capacitor (SC) dc-dc doubler., voltage, Voltage control

ID: 45659422