For typical topology of buck converter

only one terminal of the inductor is connected to the chip.So it is impossible to parallel a resistor with the inductor to damp the ring as it is used in boost converter.A novel anti-ringing circuit is presented to solve this problem.A time varying resistor network is connected between one terminal of the inductor and the power supply or the ground.In the beginning of the ring

a small resistor is used to damp the ring rapidly.But the DC current is large.With the weakening of the ring

the resistance is increased to reduce the DC current gradually.And when the ring disappears and the DC current is small enough

the network is opened.By this way

anti-ringing is achieved and no DC current exists after the ring damping is ended.A DC-DC converter with this anti-ringing circuit has been implemented in Hynix 0.5 μ m CMOS process

the result indicates that it works well and effectively.