A Colpitts-Based Frequency Reference Achieving a Single-Trim ± 120ppm Accuracy from -50 to 170°C

Abstract

A single-trim, high accuracy frequency reference is presented. The Colpitts LC-oscillator topology reduces the temperature dependencies of the LC-tank quality factor on the oscillation frequency. With a fractional divider for frequency compensation it can serve as crystal-replacement. Measurements of the prototype (16 samples) in a $0.13\mu \mathrm{m}$ high-voltage CMOS SOI process show $\pm 120\mathrm{ppm}$ accuracy from -50 to 170°C. The oscillator dissipates 3.5mW from a 2.5V supply and has 220ppm/V supply-sensitivity without supply regulation.