Tradeoffs and design of an ultra low power UHF transceiver integrated in a standard digital CMOS process

A broad range of high-volume consumer applications require low-power, battery operated, wireless microsystems and sensors. These systems should reconcile a sufficient battery lifetime with reduced dimensions, low cost and versatility. The design of such systems highlights many tradeoffs between performances, lifetime, cost and power consumption. Also, special circuit and design techniques are needed to comply with the reduced supply voltage (down to 1 V). These considerations are illustrated by design examples taken from a transceiver chip realized in a standard 0.5 μm digital CMOS process. The chip is dedicated to a distributed sensors network and is based on a direct-conversion architecture. The circuit prototype operates in the 434 MHz ISM band and consumes only 1 mW in receive mode. It achieves a -95 dBm sensitivity for a data rate of 24 kbit/s. The transmitter section is designed for 0 dBm output power under the minimum 1 V supply, with a global efficiency higher than 15%.