A fully integrated wide-band PID controller with capacitor-less compensation for step-down DC-DC converter

Abstract

A fully integrated wide-band PID controller is implemented for a buck DC-DC converter operating in voltage mode. To implement efficiently areal on-chip PID controller, a novel compensator is proposed utilizing AC ripple current of the inductor. The integral controller with an error amplifier and the proportional controller do not require any additional capacitors. The bandwidth of overall loop is about 200 kHz to support fast transient response at 1MHz switching frequency. The stability of the loop is guaranteed by theoretical analysis and measured results are provided. When the load steps for 1A, overshoot /undershoot voltages are within 50 mV and settling time is less than 90 μs. A buck converter with input of 3.6 V and output of 2.5 V for maximum power of 3.125 W is fabricated in 0.35 μm CMOS process, occupying an area of 0.75 mm 2 .

Emulated multi-path PID compensator for buck converters with large step-down ratio

“…One more advantage is that since the proposed R-C network is connected to the V X node not the output [4], one package pin can be reduced. And in this case, we do not need to consider high frequency switching noise, because it can be easily reduced by the integrator.…”

“…Recently, to overcome above issue several wide-band voltage mode buck converters with fully integrated compensator have been introduced [3], [4]. Among them, a low-power band-pass filter and an area-efficient error amplifier are designed and integrated on-chip in [3], thus realizing the solution of a monolithic Type III compensator with reduced area and power consumption.…”

“…In this paper, to overcome the aforementioned noise sensitive drawbacks and to attain a fast transient response and good stability, we adopt the emulated multi-path PID compensator [4] for a large step-down ratio buck converter.…”