Impulse-Based Scheme for Crystal-Less ULP Radios

Abstract

Abstract-This work describes a method of implementing a fully-integrated Ultra-Low Power (ULP) radio for Wireless Sensor Networks (WSN). This is achieved using a specific Medium Access Control (MAC) protocol, employing a dutycycled wake-up radio and a crystal-less clock generator, and an ad-hoc modulation scheme (Impulse Radio) with a bandwidth of 17.7 MHz in the 2.4 GHz -ISM band. The total average power consumption is expected to be less than 100 μW.

A 65-nm CMOS Temperature-Compensated Mobility-Based Frequency Reference for Wireless Sensor Networks

“…After an initial reset, the end of the time interval is denoted by the instant when the counter's output is equal to M cyc ∝ N , where M cyc can be adjusted in a temperature-dependent manner. For time intervals in the order of T meas = 100 ms as required for WSN synchronization [1], M cyc = T meas · f osc ≈ 15 · 10 3 at room temperature, which is equivalent to more than 13 bits of temperature compensating resolution.…”

“…Since the largest fraction of the energy used in each node is spent listening to the channel, synchronous networks are employed to reduce such idle listening time [1]. In that case, the receiver predicts the timeslot that the transmitter will use and turns itself off when no incoming signal is expected.…”

“…While commercial communication systems require high frequency accuracy, radios for WSN can be optimized to relax such specifications and so frequency accuracies in the order of only a few percent are needed [1] [2]. Thus, it is interesting to investigate which level of accuracy can be reached without external components, with the constraint to operate at the low voltage and power levels typical of WSN supplies.…”

A 3.8 MHz CMOS Wien-bridge oscillator with differential capacitive automatic amplitude control

“…Ultra low power (ULP) radios have become increasingly needed as various energyefficient long-battery-life wireless applications such as wireless sensor radios, internet-of-things, medical implantable devices, healthcare and monitoring circuits, emerge [1]. Many circuit design techniques for minimizing power consumption can be found in literature, for instance, in receiver [2], transmitter [3], and VCO [4].…”

High sensitivity wake-up radio using spreading codes: design, evaluation, and applications

“…Current research, into energy efficiency in sensor networks, puts the radio in sleep mode when there is no traffic to reduce energy consumption. These works can be classified into two main categories: (1) MAC protocols [2][3][4][5][6]; and (2) wake-up radios [6][7][8][9][10][11][12][13][14].…”