An asymmetric VHF self-oscillating DC-DC converter with integrated transformer

The paper presents a self-oscillating DC-DC integrated converter which is operable in the frequency range of 200MHz-260MHz. The circuit includes a cascoded power stage, and an integrated transformer. The primary of the transformer provides the transmission of power to the converter load. The secondary provides the feedback signal to the gates of cascoded transistors in the power stage. The feedback circuit includes a duty cycle detector and a pulse-shaping circuit. A detailed analysis of duty cycle detector operation is given. The conditions for a smooth start-up are indicated as well. The circuit was designed and simulated for 45 nm CMOS technology, and the calculated parameters of the duty cycle detector are compared with that of the extracted from layout converter.