Active Method for Resonant Power Supply Noise Reduction

The resonant power supply noise is recently regarded as a serious problem because it can be one of the causes of logic errors. This noise is generated by parasitic inductance on the LSI package and circuit capacitance when the current consumption is suddenly altered, and then, it is difficult to avoid the generation of this noise. Therefore, in order to reduce this noise, the on-chip passive decoupling capacitors are widely used, however these require large silicon area. The smaller silicon area is preferable because the silicon area directly affect the cost. Then, our designed circuits use not passive decaps but the active charge injection technique to realize both noise reduction and silicon area reduction. In our implementation of the active charge injection, the on-chip voltage drop detector is utilized for fast detection of voltage drop caused by resonant power supply noise. And then, the amount of injected charge is determined by the control circuit based on the analysis of the active charge injection. The charge is injected by inserting the capacitors into power supply line when required. These all circuits are implemented into actual silicon chips and we are proceeding with the measurement.