Overshoot Cancelation Based on Balanced ChargeDischarge Time Condition for Buck Converter in Mobile Applications This paper demonstrates a balanced charge and discharge time condition T2xcfx80xe2x88x9aLC4xcfx80RC when R, L and C components are chosen by a relation ZdZc2R to cancel the overshoot phenomena in buck converters. This balanced condition is derived based on the statespace technique and the superposition principle. In case ZdZcu003c2R, the overshoot voltages of this network are improved by a parallel RLC circuit. Furthermore, the ripple voltages are also reduced by the conventional spread spectrum of the pulse width modulation (PWM) method. As a result, a stepdown switching power for mobile applications is designed; the overshoot phenomena is improved from 1Vpp into 0.1Vpp, the ripple is kept very small (0.05mVpp), and the electromagnetic interference (EMI) levels are kept below 100xcexbcV, which is compared to the desired voltage of 5V.

A 30MHz DelayLineBased Buck Converter with 5.7%94.8% Switching Duty Cycle As the switching frequency of DCDC converters continues to increase, the influence of circuit delays is also increasing, which poses a great challenge to the design of a comparator. A 30MHz delaylinebased buck converter is proposed in this paper, which eliminates the need for a traditional PWM comparator, simplifies the complexity of the circuit and logic and solves a series of problems caused by comparator delays at high switching frequency. A delaylinebased voltagetodutycycle (V2D) controller is used to replace the traditional rampcomparatorbased V2D controller to achieve a wider duty cycle range. The proposed DCDC converter has been designed and simulated by Cadence software based on the 0.18xc2xb5m mixed signal CMOS process. The tunable duty cycle ranges from 5.7% to 94.8%, allowing the converter to regulate the output from 0.1V to 1.7V with 1.8V input. With a step of 400mA in the load current, the setting time is around 2xc2xb5s. The maximum load current is 1A and the peak efficiency is as high as 94.5% with 1.5V output.