Long-Range Ultrasound Wake-Up Receiver Using Pzt-Scaln Hybrid Pmut Link With Exponential Horn

This work presents a novel long-range acoustic wake-up receiver (WuRX) enhanced with an exponential horn, utilizing hybrid piezoelectric micromachined ultrasonic transducers (PMUTs) in a pitch-catch configuration. The transmitter (TX) employs a lead zirconate titanate (PZT) PMUT, while the receiver (RX) uses a 20% scandium-doped aluminum nitride (ScAlN) PMUT. Without the horn attachment, the system achieves a peak-to-peak received voltage of more than 25 mV at 95 cm. An exponential horn with a 30 mm mouth diameter, affixed to the RX, offers a voltage gain of approximately 6-8 dB over distances ranging from 50 to 90 cm. These findings are vital for Internet of Things (IoT) applications, as they demonstrate the successful reception of an On-Off-Keying (OOK) signal for the first time in a hybrid PMUT TX-RX link configuration, achieving distances of up to 70 cm with a data rate of 800 b/s and at carrier frequency exceeding 100 kHz. Furthermore, the received signal has a Signal-to-Noise Ratio (SNR) > 30 dB at 70 cm, establishing a working distance limit of 1.2 m.