Predictions of the proliferation of hundreds of billions of connected wireless devices have yet to come true. The economics of such deployments becoming feasible require that current wireless modules become smaller, cheaper, and use less power. A typical wireless device combines a RF System-on-Chip with multiple frequency references, passive components, an antenna, and a battery on a printed circuit board. The Single Chip Mote project aims to reduce the size, weight, power, and cost of these devices by eliminating the off-chip frequency references and passives. The ultimate goal being to form a 2.4 GHz wireless node by attaching only an antenna and energy source to a single CMOS die. Of particular interest is the range of applications this could enable where the size and weight of current wireless devices has prohibited their use.
This work implements a crystal-free IEEE 802.15.4 receiver that covers the data path from RF to bits. The receiver utilizes a passive front-end to reduce power and quadrature down-conversion followed by on-chip filtering and digitization. Integrated digital baseband is included for demodulation and clock recovery as well as built-in estimation of the errors in the RF channel frequency and data rate. Initial frequency calibration is performed simultaneously with bootloading using contact-less optical programming. Operation across the 0 - 70 C commercial temperature range has been demonstrated while inter-operating with commercial off the shelf IEEE 802.15.4 devices. The analog portion of the receiver, including the free-running LO, consumes 1.03 mW from a 1.5 V battery while achieving a sensitivity of -83 dBm.
Low Power, Crystal-Free Design for Monolithic Receivers
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