A 0.01 mm2 10MHz RC Frequency Reference with a 1-Point On-Chip-Trimmed Inaccuracy of $\boldsymbol{\pm 0.28\%}$ from $\boldsymbol{-45^{\mathrm{o}}\mathrm{C}}$ to $\boldsymbol{125^{\mathrm{o}}\mathrm{C}}$ in 0.18μm CMOS

CMOS frequency references based on RC oscillators are usually preferred over bulky crystals in loT applications [1–5]. However, due to the process spread and finite temperature coefficient (TC) of most on-chip resistors, RC oscillators require trimming and temperature compensation to achieve decent accuracy. Enabled by high-resolution trimming techniques such as
$\Delta\Sigma$
[1], [2] or pulse-density [3] modulation, recent designs can obtain good accuracy (<0.1 %) at the expense of large chip area. However, existing compact (<0.02mm
²
) designs suffer from frequency errors in the order of 1% or more [4], [5]. Moreover, their temperature compensation schemes usually require the use of resistors with complementary TCs, which are not available in all CMOS technologies.