A 4.4mW-TX, 3.6 mW-RX Fully Integrated Bluetooth Low Energy Transceiver for IoT Applications

Abstract

We present an ultra-low-power Bluetooth Low Energy (BLE) transceiver for Internet of things (IoT) optimized for 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with switched current source digitally controlled oscillator (DCO) and class-E/F2 power amplifier. The proposed oscillator combines the benefits of low-supply voltage operation of conventional NMOS cross-coupled oscillators with high current efficiency of the complementary push-pull oscillators. 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 modulation. The switching power amplifier operates in class-E/F2 to maximally enhance its efficiency at low output power. The receiver (RX) operates in discrete time (DT) at high sampling rate ( ∼ 10 GSample/sec) with an intermediate frequency (IF) placed beyond 1/f noise corner of MOS devices. Multistage multi-rate charge-sharing (CS) band-pass filters (BPF) are placed to achieve high out-of-band linearity, low noise, and low power consumption. Furthermore, an integrated on-chip matching network serves both PA and LNTA, thus allowing a one-pin direct antenna connection with no extra band selection filters. The transceiver consumes 2.75 mW in RX and 3.7 mW in TX when delivering 0 dBm in BLE.