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This paper proposes an ultra-low-voltage (ULV) fractional-N all-digital PLL (ADPLL) powered from a single 0.5 V supply. While its DCO runs directly at 0.5 V, a switched-capacitor DC-DC converter doubles the supply voltage to all the digital circuitry and regulates the TDC supply to stabilize its resolution thus maintaining fixed inband phase noise (PN) across PVT. The ADPLL supports a 2-point modulation and forms a Bluetooth LE (BLE) transmitter realized in 28 nm CMOS. It achieves in-band PN of -106 dBc/Hz (FoM of -239.2 dB) and RMS jitter of 0.86ps while dissipating only 1.6mW at 40 MHz reference. The power consumption reduces to 0.8 mW during BLE transmission when the DCO switches to open-loop.
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We present an ultra-low-power Bluetooth low-energy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F₂ digital power amplifier (PA), featuring high efficiency. Low 1/ f DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (10 Gsamples/s) with intermediate frequency placed beyond 1/ f noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE. ... Read more

We present a new ultra-low-power (ULP) transceiver for Internet-of-Things (IoT) optimized for 28-nm CMOS. The receiver (RX) employs a high-rate (up to 10 GS/s) discrete-time (DT) architecture with intermediate frequency (IF) placed beyond the 1/f noise corner of MOS devices. New multistage multi-rate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise and low power consumption. A transmitter (TX) employs an all-digital PLL (ADPLL) with switched-current-source digitally controlled oscillator (DCO) and switching PA. An integrated on-chip matching network serves both PA and LNTA, thus allowing a 1-pin direct antenna connection with no external antenna filters. The transceiver consumes 2.75mW in RX and 3.6mW in TX when delivering 0 dBm in Bluetooth LE. ... Read more

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