This application note describes the essential workings of an electrocardiogram (ECG). It discusses factors that disrupt the ECG signals and make reliable, highly-accurate electrical characterization difficult. The industry-standard solution for ECG electrical characterization, which uses an analog front-end and ADC combination, is explained. The note then introduces the MAX11040K simultaneous-sampling, sigma-delta ADC as a compelling, highly integrated solution that eliminates the need for the AFE, and saves both space and cost for the application.