A 320μW Receiver with -58dB SIR Leveraging a Time-Varying N-Path Filter

This paper presents a 900MHz ultra-low-power (ULP) receiver (RX) with -88dBm sensitivity and up to -58dB Signal-to-Interference Ratio (SIR) for the Internet of Things (IoT) applications. The receiver utilizes chirped On-Off-Keying (OOK) modulation for data reception. We proposed a mixer-first receiver leveraging a chirped Miller N-path filter, to achieve low-power operation while ensuring strong in-band and out-of-band interference rejection as well as sufficient RX sensitivity. A novel 4-phase chirped Miller N-path filter, using a high quality factor time-varying narrowband frequency response, is introduced in this work to facilitate bandpass filtering of the wideband chirp-OOK modulated signal, that results in enhanced RX interference tolerance. The RX chip is designed and fabricated in a CMOS 65nm technology and consumes 320μW at 5kb/s data-rate, while achieving -88dBm sensitivity at 10–3 Bit-Error-Rate (BER).