A recently developed dynamic Idd test parameter, the Energy Consumption Ratio(ECR), is based on the average current drawn by a circuit. Very fast measurement equipment is needed to measure the exact supply current transients in high-speed circuits. However, the ECR requires the average value of the transient supply current and not the exact transient. Common sampling and filtering techniques can be combined to greatly reduce measurement cost. Three approaches to combine filtering and different sampling techniques are studied in this paper. Theoretical analysis based on first order approximation and simulation results for these approaches are also presented.