A Fully-Integrated 580 μW ISM-Band Frequency Synthesizer for Implantable Medical Devices

In this paper, a fully integrated ultra-low power integer-N frequency synthesizer for operation in the 902-928 MHz ISM band is presented. This phase-locked loop based synthesizer contains an on-chip 1.830 GHz LC voltage controlled oscillator followed by a divide-by-2 prescaler that generates both in phase and quadrature differential carrier signals. The synthesizer was implemented using STMicroelectronics CMOS 90-nm process, consumes less than 580 μW of power at a supply voltage of 1 V and occupies an area of 0.7×0.8 mm². The frequency synthesizer will be used in the transceiver of an implantable wireless sensing microsystem (IWSM) dedicated to in vivo monitoring of biological parameters.