An RC Oscillator With Digital Controlled Feedback Self-trim For Temperature Compensation

With quick development of wearable device,Internet of Things,smart home and Human Machine Interaction in recent years,especially under the driver of China internet public innovative storm,the demands of smart device grow up rapidly and the needs of MCU with various functionality increasing swiftly day after day.Meanwhile the requirement of MCU design raises higher and higher and the applicable condition of temperature becomes harsher and harsher.So MCU on-chip integrated clock,RC oscillator is required not only low cost and low power but also less effected with temperature variations.Hereby this topic works on how to eliminate instability of RC oscillator with temperature variations and proposes one new method for temperature compensation.Many research results about RC oscillator temperature compensation have been published.However,most of approaches are either complicated to implement with high cost or unable to trim dynamically when looking into them,so it's bad for both large range of temperature cancellation and reliability of device aging.By combining the advantages of different techniques,this article identifies finally the best way of temperature compensation as self-calibrated loop back design with digital trim circuit.Nevertheless,dynamic temperature cancellation of oscillator has to complete at fastest speed.Therefore,the selection and optimization of search algorithm of digital trim code becomes another important question.After research and analysis on the popular search algorithm of digital trim code used in present testing procedure,one better search algorithm rises up.At the same time,combination with the structure of the RC oscillator andthe realization of the fine-tuning circuit,verification by software and optimization of search algorithm make it easier to implement in hardware.The whole design realization requires check by circuit mix-signal simulation with 0.13?m CMOS process corners and 1.8V to 3.6V and makes sure frequency less than ±1.5% over temperature range of-35? to105?.At last,tests on silicon promise the work.