A CMOS Dual-RC frequency reference with ±250ppm inaccuracy from -45°C to 85°C
Çağrı Gürleyük (TU Delft - Electronic Instrumentation)
L. Pedala' (TU Delft - Electronic Instrumentation)
Fabio Sebastiano (TU Delft - (OLD)Applied Quantum Architectures)
K. A.A. Makinwa (TU Delft - Microelectronics)
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Abstract
To comply with wired communication standards such as USB, SATA and PCI/PCI-E, systems-on-chip require frequency references with better than 300ppm accuracy. LC-based references achieve 100ppm accuracy [1], but suffer from high power consumption (∼20mW). Thermal diffusivity (TD) references require less power (∼2mW), at the expense of less accuracy (1000ppm) [2]. RC-based references offer the lowest power consumption, but their accuracy is typically limited to ∼0.1% [3]. In RC relaxation oscillators, comparator offset and delay are the major sources of inaccuracy [4,5]. References based on frequency-locked loops (FLLs) circumvent these by locking an oscillator's frequency to the time-constant of an RC filter, but their accuracy is then limited by the nonlinear temperature dependency of on-chip resistors [3,6].