A Current Controllable Active Transient-Voltage Compensation Circuit for Voltage Regulator Module

In this article, a novel current controllable active transient-voltage-compensation circuit (CC-ATVCC) is proposed to mitigate output voltage overshoot and undershoot in voltage regulator module (VRM) during load transients. The current difference between the VRM output and the load is compensated by field effect transistors in the proposed CC-ATVCC so that the output voltage spikes are suppressed. In the proposed CC-ATVCC, a high gain analog drive circuit, consisting of an operational amplifier cascaded with a common-source amplification circuit, provides adjustable drive voltage, which flexibly changes the compensation current. Furthermore, a time-domain model is developed in this article to analyze the interaction between VRM and the proposed CC-ATVCC, guiding the circuit design under universal conditions. Finally, the proposed CC-ATVCC has been built and tested in a 12-phase 500 A interleaved buck converter. The results show that the overshoot of the output voltage can be reduced by 34% using the proposed CC-ATVCC and the footprint of CC-ATVCC is only 10% compared with the traditional capacitor-only solution. The proposed CC-ATVCC can reduce the number of output capacitors and greatly increase the power density of VRM.