System Design of a 2.75-mW Discrete-Time Superheterodyne Receiver for Bluetooth Low Energy

This paper introduces a system-level approach to develop the first-ever fully discrete-time (DT) superheterodyne receiver (RX) for Internet-of-Things applications, such as Bluetooth low energy (BLE). It exploits fast switching speed and low internal capacitances of deep-nanoscale CMOS devices to realize a high intermediate-frequency (IF) architecture based on switched-capacitor-based charge-domain bandpass filtering. Power consumption is minimized by aggressively reducing the size of MOS devices and judiciously applying a sampling-rate decimation. The resultant increase in the flicker noise is mitigated by placing the IF frequency beyond the flicker corner frequency. Likewise, the decimation-induced aliasing is mitigated by DT filtering of preceding stages. The BLE RX is fully standard-compliant and achieves a record-low-power consumption of 2.75 mW (including its local oscillator) while delivering the state-of-the-art performance: 6.5-dB noise figure and −19-dBm third-order input intercept point, with a direct antenna connection and thus without the typical external bandpass filters.