Fully integrated tunable wideband true time delay for wireless sensor networks

High Performance Wireless Sensor Networks (HP-WSN) for critical, low latency applications such as traffic control, industrial process control, smart structures and smart vehicles has been a fast-growing field. Nevertheless, efforts towards new systems and circuit architectures to enable real-time, predictable and reliable HP-WSN have been limited, specially for reliable, low latency wireless links. This paper presents for the first time, to authors' knowledge, a low power, wideband, large delay, tunable, compact, CMOS-scalable and frequency-independent true time delay cell that enables wideband beamforming on HP-WSN. This new architecture, inspired on bucket brigade devices and N-path structure, is especially well suitable for sub-3 GHz ISM bands, where most of WSN transceivers work. Post-layout simulations of a circuit demonstrator has shown a continuous time delay between 100 − 1000 ps with 0.5% delay variation over 0 − 3 GHz band. The layout area is only 0.025 mm² and it consumes 10 − 19 mW, including buffers. It has also established a record of delay-per-area density of 40000 ps/mm²