Band frequency generation using mixed signal controlled ring — Oscillator

Basic building blocks for ring oscillator are inverters. Odd numbers of such blocks are cascaded to form a positive feedback loop. In this paper frequency of oscillation of the Ring Oscillator is varied by employing varying load which decides delay of each inverter stage and by varying the current sink/source path transistors in a digitally controllable ring oscillator is demonstrated. Design is verified using circuit simulator LTspice IV by Linear Technology. The minimum dimension design is 180 nm. PMOS should be 3 times larger than NMOS.