1. Rezayee, A., & Martin, K. (2001). A three-stage coupled ring oscillator with quadrature outputs. In The 2001 IEEE international symposium on circuits and systems (ISCAS) (Vol. 1, pp. 484–487).
2. Hajimiri, A., & Lce, T. H. (1999). The design of low noise oscillators. Berlin: Kluwer Academic Publishers.
3. Kim, G., Ueda, K., Cha, S., Ida, T., Shimizu, Y., Matsuoka, T., & Taniguchi, K. (2007). Process variation compensation technique for voltage-controlled ring oscillator. IEEJ Transaction on Electrical Electronic Engineering, 2, 189–191.
4. Marzaki, A., Bidal, V., Laffont, R., Rahajandraibe, W., Portal, J. -M., Bergeret, E., & Bouchakour, R. (2013). On the investigation of a novel dual-control-gate floating gate transistor for VCO applications. Buletin Teknik Elektro dan Informatika, 2, 212–217.
5. Mandal, M. K., & Sarkar, B. C. (2010). Ring oscillators: Characteristics and applications. Indian Journal of Pure & Applied Physics, 48, 136–145.