A Sub-100 W MICS/ISM Band Transmitter Based on Injection-Locking and Frequency Multiplication Jagdish Pandey, Student Member , IEEE, and Brian P . Otis , Senior Member , IEEE

Abstract

For fully autonomous implantable or body-wo rn devices running on harvested energy, the peak and average power dissipation of the radio tr ansmitter must be minimized. Additionally, link symmetry must be maintaine d for peer-to-peer network applications. We propose a highly integrated 90 W 400 MHz MICS band transmitter with an output power of 20 W, leading to a 22% global ef ficiency—the highest reported to date for low-power MICS band systems. We introduce a new transmitter architecture based on cascaded multi-phase injec- tion locking and frequency multiplicati on to enable low power operation and high global ef ficiency. Our architecture eliminates slow phase/delay-locked loops f or frequency synthesis and uses injection locking to achieve a sett ling time 250 ns permitting very aggressive duty cycling of the transmitter to conserve energy. At a data-rate of 200 kbps, the transmitter achieves an energy efficiency of 450 pJ/bit. Our 400 M Hz local oscillator topology demonstrates a figure-of-merit of 204 dB while locked to a stable crystal reference. The transmitter occupies 0.04 mm of active die area in 130 nm CMOS and is ful ly integrated except for the crystal and the matching network.