An ultra-low-power VAD hardware implementation for intelligent ubiquitous sensor networks

We propose a power management method using a digital voice activity detection (VAD) module for intelligent ubiquitous sensor systems. When this VAD module detects a speech signal, a main signal processing circuit is connected to a power source. When no speech signal is detected, most circuits except VAD are blocked off, thereby reducing stand-by power for the specialized sensor nodes used for speech signal processing. We implemented the VAD algorithm, using zero crossing of input signals to an FPGA, thereby achieving 2.10 mW operation. We synthesized this VAD module using CMOS 0.18-mum process, achieving 3.49 muW power consumption for operation at 1.8 V and 100 kHz.