This　paper　presents　a　Bluetooth　low-energy　(BLE)　transceiver　(TRX)　achieving　ultra-low-power　operation　for　Internet-of-Things　(IoT)　applications.　The　proposed　TRX　utilizes　a　wide-bandwidth　low-power　fractional-N　digital　phase-locked　loop　(DPLL)　as　a　central　component　to　perform　multiple　roles:　a　direct　frequency　modulator　for　the　transmitter　(TX),　an　analogto-digital　converter　(ADC)　for　the　receiver　(RX),　a　local　oscillator　for　RX,　and　a　frequency　and　phase　synchronizer　for　the　RX.　The　DPLL-based　single-path　downconversion　method　is　adapted　to　halve　the　analog　baseband　circuit　to　further　reduce　the　power　consumption　while　maintaining　a　high　interference　rejection.　A　DPLL-based　ADC　with　a　digital-to-analog　converter　feedback　greatly　improves　the　ADC　dynamic　range,　which　improves　the　RX　sensitivity　and　interference　tolerance.　By　maximally　reducing　the　required　radio　frequency　and　analog　front-end　components　in　RX,　an　RX　power　consumption　of　2.3　mW　is　achieved　with　a　-94　dBm　sensitivity.　The　RX　also　satisfied　all　interference　requirements　with　a　certain　margin.　A　5.0-mW　TX　is　achieved　when　delivering　an　output　power　of　0　dBm　with　a　frequency-shift　keying　error　of　only　1.89%.