Low-Phase-Noise CMOS Relaxation Oscillators for On-Chip Timing of IoT Sensing Platforms

Abstract

The design of low-phase-noise fully integrated frequency references is often a critical aspect in the development of low-cost integrated circuits for communication interfaces, sensing platforms, and biomedical applications. This work first discusses relaxation oscillator topologies and design approaches aimed at minimizing the phase noise; then, a single-comparator low-phase-noise RC relaxation oscillator is proposed, featuring a novel comparator self-threshold-adjustment technique. The oscillator was designed for a 10 MHz oscillation frequency. Electrical simulations performed on a 0.18 μm CMOS design confirmed that the proposed technique effectively rejects the flicker component of the comparator noise, allowing for a 152 dBc/Hz figure of merit at a 1 kHz offset frequency. The standard deviation of the jitter accumulated across 10k oscillation cycles is lower than 4 ns. The simulated current consumption of the circuit is equal to 50.8 μA with a 1.8 V supply voltage. The temperature sensitivity of the oscillation frequency is also notably low, as its worst-case value across process corners is equal to −20.8 ppm/°C from −55 °C to 125 °C.

Probabilistic Analysis of an RL Circuit Transient Response under Inductor Failure Conditions

“…Similarly, an electric circuit which only has resistors and an inductor is called an RL circuit and has multiple types of applications in a diverse range of electrical devices and equipment [7][8][9]. The applications of RC and RL circuits can be broadly categorized in two domains, i.e., timeand frequency-domain applications [10][11][12][13][14]. In typical time-domain applications, an RL circuit may be employed for the control of the timing of an event by managing the time it takes to energize or de-energize the inductor.…”