Duty cycle and frequency are important characteristics of periodic signals that are exploited to develop a variety of application circuits in IC design. Controlling the duty cycle and frequency provides a method to develop adaptable circuits for a variety of applications. These applications range from stable on-chip clock generation circuits, on-chip voltage regulation circuits, and Physical unclonable functions for hardware security applications. Ring oscillator circuits that are developed with CMOS inverter circuits provide a simple, versatile flexible method to generated periodic signals on an IC chip. A digitally controlled ring oscillator circuit can be adapted to control its duty cycle and frequency. This work describes a novel current starved ring oscillator, with digitally controlled current source based headers and footers, that is used to provide a versatile duty cycle and a precise frequency control. Using this novel circuit, the duty cycle and frequency can be adapted to a wide range of values. The proposed circuit achieves i) a controlled duty cycle that can vary between 20% and 90% with a high granularity and ii) a compensation circuit that guarantees a constant duty cycle under process, voltage, and temperature (PVT) variations. A novel application of the proposed PWM circuit is the design and demonstration of a reliable and reconfigurable Duty-cycle based Physical unclonable function (PUF). The proposed PWM based PUF circuit is demonstrated to work in a reliable and stable operation for a variety of process, voltage and temperature conditions with circuit implementations using 22nm and 32nm CMOS technologies. A comparative presentation of the duty cycle based PUF are provided using standard PUF figures of merits.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-8667 |
| Date | 16 November 2018 |
| Creators | Azhar, Mahmood Javed |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
Page generated in 0.0023 seconds