Intelligent Control Strategies For High Performance Voltage Regulator Module

The rapid development of modern microprocessor has put forward much higher performance requirements to its power supply unit - voltage regulator module (VRM), which including the high current driving capacity under very low supply voltage, high voltage stability at high slew-rate load current transient and so on. Thus, fast transient response has become an essential design objective of VRM and attracted a lot of research efforts recently.The researches on improvement of the transient response mainly focus on two areas: topology and control methods. Performance improvement by new topology, such as multi-phase interleaved topology and stepping inductor topology, is usually at the expense of larger circuit cost. On the other side, proper control method could significantly improve the response performance costless, which shows that the research on control method for fast response is significant and has good applied prospects.In view of that mentioned above, this thesis focused the efforts on the research on control strategies for VRM. Through analyzing and comparing the priors control methods, a novel capacitor current hysteretic control method based on sliding mode theory was proposed, which inherits the advantages of fast response and robust performance of traditional hysteretic control mode, while eliminating the drawbacks such as large output ripple (voltage mode), slow transient response (inductor current hysteretic mode). And one-cycle stability was achieved by employing the sliding mode theory.In order to further improve the transient response for large load step, a linear transient current compensation strategy was proposed. Meanwhile, considering the main drawbacks of hysteretic control, i.e. varying frequency, a simple but effective frequency modulation loop was designed and added to lock the switching frequency for the proposed hysteretic control mode.The proposed VRM controller chip was designed and manufactured in TSMC 0.35umCMOS mixed signal process. The die size is 2.5mm X 2.0mm. Simulation results show that thecontroller has a fast dynamic response with constant switching frequency, which is consistent with design expectations.