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Clock Generator with Exponentially Increasing Frequency Using Switched-Capacitor Circuit

Aatiqah Aziz1, Shinya Terada2, Kei Eguchi3, and Ichirou Oota 1
1. Department of Information, Communication and Electronic Engineering, National Institute of Technology, Kumamoto College, Kumamoto 861-1102, Japan
2. Department of Control and Information Systems Engineering, National Institute of Technology, Kumamoto College, Kumamoto 861-1102, Japan
3. Department of Information Electronic Fukuoka Institute of Technology, Fukuoka 811-0295, Japan
Abstract—Charging and discharging waveforms in an RC circuit are changed exponentially. The change gradually decreases over time and approaches a steady-state value, since the power of the exponential is negative. However, depending on applications, a diverging signal may be required. In this case, the power of the exponential is positive, and the signal gradually increases over time. In this paper, a clock generator is proposed whose frequency is increased exponentially over time. The proposed circuit can generate exponentially increasing voltage and clock signals with high accuracy over a wide operating range by using Switched-Capacitor (SC) technique. The generated voltage and the clock frequency are derived theoretically. Moreover, the design formulas for finding the circuit parameters with the initial value and the final value are also derived. The theoretical analysis of the proposed circuit is confirmed by experiments and SPICE simulations. From the experiments and the simulations, the clock frequency and the voltage are changed exponentially 1 kHz ~ 20 kHz and 0.4 V ~ 7.9 V, respectively. As an application, the Cockcroft-Walton circuit is driven by the proposed clock generator. 
 
Index Terms—charge pump circuit, clock generator, exponential increase, fast start-up, small inrush-current, switched-capacitor

Cite: Aatiqah Aziz, Shinya Terada, Kei Eguchi, and Ichirou Oota, "Clock Generator with Exponentially Increasing Frequency Using Switched-Capacitor Circuit," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 9, No. 1, pp. 49-55, January 2020. Doi: 10.18178/ijeetc.9.1.49-55
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