Design Automation of a Digitally Controlled Ring Oscillator using CUAS Cell Creator Framework

An automated design methodology for a digitally controlled ring oscillator (DCRO) is proposed in this paper. Through the CUAS Cell Creator (CCC) framework, an implementation of a single-ended RO (SERO) controlled by a capacitive DAC based on split architecture is performed with grid interpolation. In addition, a model which estimates the frequency of a RO using LUTs is proposed. The design of a low-dropout regulator (LDO), with a symmetrical OTA as error amplifier (EA), is also considered, following g<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf>/I<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</inf> methodology, to reduce the impact of power supply variations. Regarding process dependence, the response is maintained in range using a sensing block which varies the regulated node accordingly. The design flow is tested with an example in 65-nm CMOS technology.