A 2GHz 52 μW Wake-Up Receiver with -72dBm Sensitivity Using Uncertain-IF Architecture

A wake-up receiver (WuRx) is used in wireless sensor networks (WSN) to detect wireless traffic directed to a node´s receiver and activate it upon detection, improving network latency and energy dissipation by maximizing data transceiver sleep time. The always-on nature of the WuRx sets a power dissipation floor for the entire system. In realistic WSN scenarios, the adoption of a WuRx leads to energy savings only if it can be realized with about 50muW of power dissipation in Lin, E.Y., et al, (2004), testing the limits of low-power receiver design. While diode detectors provide for the simplest detector structure, such receivers are strongly gain-limited due to the thresholding effect of the nonlinear detector in Pletcher, N., et al, (2007) and adding gain at RF to improve sensitivity only increases power consumption. A more attractive approach is to adopt a heterodyne architecture, where the extra gain needed for robust energy detection can be obtained at an intermediate frequency (IF) with a much lower power cost. However, a survey of previous receiver designs for WSN reveals that the power requirements of the required local oscillator (LO) exceed the total power budget of the WuRx in Otis, B., et al, (2005).