A 16MHz CMOS RC Frequency Reference with ±400ppm Inaccuracy from -45°C to 85°C after Digital Linear Temperature Compensation

Abstract

Systems-on-chip traditionally rely on bulky quartz crystals to comply with wired communication standards like CAN or USB 2.0. Integrated frequency references with better than 500ppm inaccuracy could meet this need, resulting in higher integration and lower cost. Candidate architectures have employed RC-, LC- or TD (thermal diffusivity)-based time constants, all of which can be realized in standard CMOS. Compared to LC (sim 20mathrm{mW}, sim 100mathrm{ppm}) [1] or TD (sim 2mathrm{mW},sim 1000mathrm{ppm}) [2] references, RC references offer the lowest power consumption and competitive accuracy (< 1mathrm{mW}, 200mathrm{ppm})[3]. However, due to the nonlinear temperature dependence of on-chip resistors, such references require complex temperature-compensation schemes based on higher-order correction polynomials and extensive calibration [3], [4], or complicated analog compensation networks [5].