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Item type:Publication, Access status: with files , Low-power relaxation oscillator with temperature-compensated thyristor decision elementsThis paper presents a low-power 140 kHz relaxation oscillator (ROSC) for low-frequency clock generators and timers. In voltage-mode ROSCs, unavoidable shunt current consumption results from voltage slewing at the integration capacitor. The proposed circuit employs CMOS thyristor-based decision elements which effectively reduce shunt currents by exploiting internal positive feedback. A complementary-to-absolute temperature (CTAT) current reference compensates for the frequency’s temperature sensitivity. In order to achieve high negative temperature coefficient with small area and power overhead, the circuit reuses parts of the positive-to-absolute temperature (PTAT) bias generation block. Moreover, a modified start-up circuit with 3 times faster oscillator power-on is presented. The 0.09 mm 2 oscillator consumes 6.5 nW/kHz at 1.5 V to 2.5 V supply if only the CTAT source is considered, resulting in a power consumption of 907.4 nW at 140 kHz. The measured temperature coefficient of - 514.7 ppm/K in the range of −40 °C to 85 °C shows an improvement of 5.5 times compared to the uncompensated case. A supply sensitivity of 2.62 %/V, a frequency resolution of 2.67 kHz/step, and an average clock jitter of 6.02 ns are achieved. The oscillator is embedded in an ultra-low power system-on-chip for autonomous environmental sensing.Publicationtype: Journal Article23 41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Low Power CMOS Thyristor-Based Relaxation Oscillator with Efficient Current CompensationThis paper presents a microwatt voltage-mode relaxation oscillator, whose main innovation is the utilization of CMOS thyristor circuits as decision elements. It provides stable on-chip 140 kHz clock source for ultra-low power autonomous systems. The employment of CMOS thyristors reduces the dynamic power consumption compared to the classical topology, but introduces strong PTAT temperature dependency. This is compensated by a CTAT current reference, which recycles parts of the PTAT bias generation block and therefore relaxes overall chip area and power penalty. The reference start-up time is effectively decreased by a modified start-up circuit, which shortens system power-on. The oscillator excluding the recycled PTAT occupies 0.09 mm2 and draws 907.4 nW from 1.8 V supply, resulting in a Figure-of-Merit of 6.5 nW/kHz. With the PTAT reference accounted, 1.20 μW, 8.6 nW/kHz and 0.11 mm2 were achieved. Measurements show a temperature coefficient of-514.7 ppm/K in the range of-40°C to 85°C with the proposed compensation, achieving an improvement of 5.5 times compared to the simulated uncompensated case. The frequency variation is 2.62 %/V N within supply voltage range of 1.5 V to 2.5 V.Publicationtype: Conference Paper53