Review on the Temperature Resilient On-Chip Frequency Generation Circuit Techniques

This article summarizes temperature-resilient on-chip frequency generation circuit techniques, focusing on low-power and compact implementations suitable for miniaturized Internet of Things (IoT) systems. While various types of oscillators–such as MEMS, crystal, LC, RC, gate-leakage, and ring oscillators–are employed to generate reference frequencies, on-chip RC oscillators are particularly attractive due to their compatibility with standard CMOS processes and significant improvements in power consumption and frequency accuracy over the last decade. However, without consideration of temperature dependency, the frequency stability can be severely degraded, which limits their applicability in high-precision systems. To address this challenge, we investigate temperature-dependent non-idealities of the on-chip RC oscillators and introduce various on-chip RC oscillator architectures, including frequency-locked loop-based oscillators, and techniques to improve temperature dependency in the RC oscillators, such as current mismatch, comparator delay, and comparator input offset.