Super-regenerative receivers (SRR) are known for their ultra-low power (ULP) consumption. However, its wide frequency selectivity seriously degrades performance especially in the presence of interference. An attractive approach to address this problem is by lowering the quench rate of the SRR to the modulation rate. However, this brings in uncertainty due to lack of oversamples and leads to the timing synchronization problem in demodulation. This paper proposes a timing synchronization method for SRR with a single quench cycle per modulated symbol. A novel asynchronous preamble structure and an associated timing synchronization algorithm are proposed. Significant performance gains are obtained due to the improved frequency selectivity enabling the SRR system to adhere to the constraints set forth by the IEEE 802.15.4 standard while maintaining the ULP advantage. © 2014 IEEE.