Patent ID: 7818590

Claim:
An apparatus for controlling a supply voltage using hierarchical performance monitors comprising: a supply voltage generator generating a supply voltage having a controllable level; a signal generator generating a first signal having a first frequency and a second signal having a second frequency; a plurality of local performance monitors, each of the plurality of local performance monitors receiving the second signal having the second frequency and the supply voltage output from the supply voltage generator, monitoring whether a level of the received supply voltage corresponds to the received second frequency based on a predetermined functional relationship between the received second frequency and the received supply voltage, and generating a local feedback signal according to a result of the monitoring; and a global performance monitor receiving the second signal having the second frequency, the supply voltage output from the supply voltage generator, and the local feedback signals output from the plurality of the local performance monitors, respectively, monitoring whether the received supply voltage corresponds to the received second frequency based on the received signals, and generating a global feedback signal according to a result of the monitoring, wherein the supply voltage generator controls a level of the supply voltage based on the second signal having the second frequency and the global feedback signal, and generates an indicating signal based on a controlled level of the supply voltage, and wherein the signal generator generates the first signal having one of the first frequency and the second frequency based on the indicating signal output from the supply voltage generator.