A 0.01 mm210MHz RC Frequency Reference with a 1-Point On-Chip-Trimmed Inaccuracy of ±0.28% from -45°C to 125°C in 0.18μm CMOS
Xiaomeng An (Student TU Delft)
Sining Pan (Tsinghua University, TU Delft - Electrical Engineering, Mathematics and Computer Science)
Hui Jiang (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Kofi A.A. Makinwa (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
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 DeltaSigma [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 (<0.02mm2) 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.