Patent ID: 7498793

Claim:
A current-mode converter, comprising: an inductor; a power switch coupled to the inductor, the power switch being capable of providing a voltage signal according to a current flowing through the power switch; an oscillator for generating a ramp signal, wherein the oscillator further comprising, a current source, a capacitor being having an upper plate, the capacitor being charged by the current source, a resistor coupled to the capacitor, a switch coupled to the resistor to control charging and discharging of the capacitor to provide the ramp signal at the upper plate of the capacitor, a plurality of comparators comparing the ramp signal with a plurality of threshold voltages, and a logic unit controlled by the plurality of comparators and capable of generating a pulse signal to control the switch; an adder coupled to the inductor, the adder being capable of adding the ramp signal from the oscillator to the voltage signal and generating a sum signal; an error amplifier for comparing a feedback voltage with a reference voltage and generating an error signal; a comparator for comparing the error signal with the sum signal and generating a pulse-width modulation (PWM) signal; and a driver for receiving the PWM signal and generating a switch control signal to control the power switch and the adder.