A long-range, fully-integrated, regulator-less CMOS power amplifier for wireless sensor communications

A CMOS PA system intended for long-distance sensor communication is presented. The PA utilizes a dynamic-VDD and operates directly off of a super-capacitor energy-storage element, obviating the need for a voltage regulator. A power-combining PA impedance scaling approach has been implemented to eliminate energy loss from a high-current voltage regulator. The device integrates a 2-to-1 power combiner with a set of pre-drivers and an output stage. The PA monitors the output power, and digitally modulates the PA load impedance. The entire power control loop is integrated in a 90nm, 9-metal-layer TSMC process and delivers 24dBm of output power at 1.9GHz, making it suitable for sensor data communication over distances of several hundred meters. During a TX-burst, the PA VDD varies from 2.5V to 1.4V, while the power control loop maintains constant output power with an accuracy of 1.6dB.