Adaptive voltage scaling (AVS) technology is gradually popularized in power management circuits to reduce power consumption of the digital load. Conventional on-chip AVS function is realized by a complex digital controller, which could cause extra consumption of the power management circuit. This paper proposes a simple AVS circuit based on dominate-pole compensation (DPC). With DPC technique, the buck converter with AVS function is ensured stably. A hybrid DPWM is design to regulate the duty ratio of the switching pulse, hence to scale the output voltage according to the operating frequency of the digital load. The range of voltage scaling is 0.9V-2.1V and the corresponding load frequency is 30MHz-120MHz in our design. Simulation results and layout of the digital load with the proposed AVS circuit are given out in this paper.