Optimization of CCOs with Implantable MEMS Pressure Sensors for Cardiovascular Applications

Abstract

Implantable biomedical devices for telemonitoring Cardiovascular Diseases (CVD) generally comprise MEMS-type sensors used to acquire physiological signals, as well as CMOS electronics to perform powering, signal conditioning and data transmission. This work targets the optimization of several Capacitor-Controlled Oscillator (CCO) topologies for implantable applications, based on the analysis of their most relevant performance parameters. Comprehensive simulations allowed the estimation of the output frequency, percentage tuning range, maximum linearity error, phase noise and power consumption for each design. These performance metrics have been used to obtain the Figure of Merit for every CCO, showing a better overall response from single-ended ring topologies symmetrically loaded. However, the robustness of differential topologies against supply and substrate noise, and the voltage tuning range of sawtooth CCOs, increase their potential usage for implantable applications.