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Title High Resolution CMOS Frequency-to-digital Converter for a Fine Dust Sensor using a MEMS Resonator
Authors (Hyunwon Moon)
Page pp.168-176
ISSN 1598-1657
Keywords Fine dust sensor; MEMS resonator; Delay-locked loop (DLL); oscillator; CMOS; high resolution; 38453
Abstract A high resolution, low power CMOS oscillator and frequency-to-digital converter for a fine dust sensor using a MEMS resonator is proposed. The proposed frequency-to-digital converter is realized based on dual-loop hybrid delay-locked loop to distinguish fine frequency variations according to very small fine dust concentrations, and simultaneously applied binary and square search algorithms to obtain accurate digital codes indicating frequency changes. An oscillator and frequency-todigital converter for a fine dust sensor is implemented using the 0.18-μm CMOS process. The core size of the fabricated MEMS oscillator and frequency-to-digital converter is 0.9 mm2 and consumes about 16 mW of power at 1.8 V supply voltage. The proposed frequency-to-digital converter covers the input frequency range of 1.7 GHz to 2.3 GHz with 1 bit resolution of about 3 MHz.