An 8.1 dB SNRMIN, 17.8 pJ/Conv-Step, Code-Domain Noise Suppression Baseband Scheme for Ultra-Low-Power Receiver

This brief investigates the minimum signal-to-noise-ratio requirement ( ${SNR} {_{\text {MIN}}}$ ) for reliable baseband decoding as a function of code length and oversampling rate. Based on this analysis, we propose a baseband processing scheme for code-domain noise suppression that leverages a level-crossing ADC (LC-ADC) front end. Compared with conventional comparator-based architectures, the proposed design significantly reduces the ${SNR} {_{\text {MIN}}}$ , thereby improving receiver sensitivity. A prototype circuit was fabricated in a 65 nm CMOS process to validate the proposed approach. Measurement results at 100 bps with a 10-bit wake-up code demonstrate an ${SNR} {_{\text {MIN}}}$ of only 8.1 dB and an energy efficiency of 17.8 pJ per conversion step. Beyond ultra-low-power radios, this proposed technique is applicable to a broad range of low-power, weak-signal detection systems.