Low power single chip radio technologies for wireless sensor network applications

μNode is a sensor node using a single chip radio. It can serve as a node to form a wireless sensor network. This node requires a small form factor, low power and low cost.;Due to its low cost and easy integration, on-chip antennas in CMOS processes have been studied over last 15 years. Simulations suggest that a 1-cm on-chip antenna covered by dielectric material with dielectric constant equal to 4 can form a wireless communication link at 2.4 GHz with a useful distance of 20 m. On-chip antennas are also less sensitive to surrounding objects compare to off-chip antennas especially when a nearby silicon chip is considered. This is important for a small form factor radio such as μNode.;A technique for integrating a wireless switch to turn an M&M™ sized radio on or off is demonstrated using a 130-nm digital CMOS process. The switch circuit like a passive radio frequency identification system picks up an amplitude-modulated 5.8-GHz carrier and converts it to DC to power up a portion of radio connected to a coin-cell battery. The radio uses a 2.4/5.8 GHz dual band antenna. This wireless switch is added between the antenna and transmit/receive (T/R) switch of the radio. By incorporating an impedance transformation network, the wireless switch input sensitivity is reduced to ∼-13 dBm. Inclusion of this circuit degrades the maximum transmitted power and sensitivity of 2.4-GHz transceiver by ∼0.3 - 0.5 dB. An RF clamp of wireless switch also limits the input power above ∼12 dBm to protect the switch and transceiver. The wireless switch occupies an area of ∼0.24 mm 2.;Approaches to reduce power consumption and area are incorporated into a 2.4-GHz receiver front-end incorporating a phase locked loop (PLL). The 2.4-GHz PLL using a relaxation voltage-controlled oscillator achieves phase noise of -92.8 dBc/Hz at 1-MHz frequency offset. The LO driver and mixer are co-optimized for gain, noise figure and power consumption. The front-end occupies an active area of 0.12 mm2 and achieves voltage conversion gain of 40 dB, noise figure of 9.2 dB at 1-MHz intermediate frequency while consuming only ∼3.5 mW.