FOR WIRELESS sensor networks, ultra-wideband impulse radio (UWB-IR) is increasingly being adopted for its low power consumption and high data rates. Rather simple transceiver architectures make UWB-IR a very low-energy solution. Yet such simplicity often implies low transmitter efficiency coupled with high sensitivity of non-coherent receivers to in-band interferers. Recently, an approach was proposed in which the transmitter would generate pulses with the maximum energy allowed by the power spectral-density regulations. This approach, which could improve efficiency while relaxing the receiver's sensitivity requirements, is credited to Silvia Sold, Michele Caruso, Andrea Bevilacqua, Andrea Gerosa, Daniele Vogrig, and Andrea Neviani from Italy's University of Padova.
The researchers' pulsed transmitter wakes up when it is triggered by a digital signal. It then generates a pulse and automatically switches off in less than 2 ns. A prototype of the transceiver delivers 13 pJ/pulse energy to the antenna, consuming about 190 pJ with high efficiency. The receiver achieves sensitivities of -87 and -70 dBm at pulse repetition frequencies (PRFs) of 100 kHz and 5 MHz, respectively, while consuming 4.2 mW. At 5.4 GHz, it can tolerate interferers to -12 dBm. See "A 5 Mb/s UWB-IR Transceiver Front-End for Wireless Sensor Networks in 0.13 m CMOS," IEEE Journal Of Solid-State Circuits, July 2011, p. 1636.