A 486 µW All-Digital Bluetooth Low Energy Transmitter with Ring Oscillator Based ADPLL for IoT applications

this paper presents an all-digital Ring Oscillator (RO) based Bluetooth Low-Energy (BLE) transmitter (TX) for ultra-low-power radios in short range IoT applications. It employs a wideband ADPLL featuring an f RF /4RO, with an embedded 5-bit TDC. A 4X frequency edge combiner is used to generate the 2.4GHz signal. This helps reduce the power consumption and enhance its phase noise performance at the same time. A switch-capacitor PA is optimized for high efficiency in low power mode. The TX is designed at the phase noise limit for BLE and in low power mode it consumes 486 µW while configured as a non-connectable advertiser, which has been validated by wirelessly communicating beacon messages to a mobile phone.