Header menu link for other important links
Capacitive boosted ring oscillators for all-digital phase-locked loops (ADPLLs)
Published in World Scientific
Ring oscillator (RO)-based digital phase-locked loops (DPLLs) are very attractive for system-on-chip applications due to their tuning range, good phase noise property but suffer from compactness and power requirements. In this work, the concept of capacitive boosting as one of the key solutions which enhances the amplitude of oscillations of the RO is proposed, making it a suitable solution to the biomedical applications, specifically for medical implant communication system (MICS) band of operation ranging from 400 MHz to 405 MHz. With coarse and fine-tuning blocks, this digitally controlled oscillator (DCO) promises a good resolution. The coarse tuning is achieved using conventional MOS capacitors and the fine-tuning is achieved by controlling the fractional metal oxide semiconductor (MOS) capacitances. To benchmark the performance metrics of the single-stage RO in this work, simulations were performed for 680 mV supply voltage in 45 nm complementary metal oxide semiconductor (CMOS) technology. The output varies in the range from -0.422 V to þ1:102 V, indicating about 224% amplitude enhancement. Despite process voltage temperature (PVT) variations, we can see little impact on the boosted output levels. The designed DCO operates up to a maximum frequency of 495 MHz at 0.68 V. The proposed RO has lesser power consumption than any conventional RO, operating at a center frequency of 402 MHz, thus making it better suitable for the MICS band of applications. Phase noise of -96:26 dBc/ Hz at an o®set of 200 kHz was obtained. The proposed differential DCO consumed power was 95.26 μW. The figure of merit (FoM) for this DCO is -174:39 (dBc/Hz). The area consumed by the DCO is 0.01872 mm2 © World Scientific Publishing Company
About the journal
JournalJournal of Circuits, Systems and Computers
PublisherWorld Scientific