Experimental Validation of the Advantages provided by Linear - Non - Linear Control in Multi-phase VRM

The power supplies that feed the recent microprocessors, known as Voltage Regulator Modules (VRM), should provided a low and well regulated voltage (0.8-1.5V) under very exigent conditions, since the microprocessor can demand high currents in a very short period of time. There are two solutions in order to design the VRM to meet these specifications: modifying either the topology or the control strategy. Nowadays, to modify the control strategy becomes a more attractive solution. The linear-non-linear (LnL) control strategy allows reducing the switching frequency and the number of phases compared with using a classical linear control. In this paper, the advantages of LnL control are validated by means of experimental measurements in VRM prototypes with four and eight phases, and with switching frequencies of 300 kHz and 600 kHz. The system configuration can be easily adapted since the control has been implemented in a FPGA.