Design of a Low-Power Ground-Free Analog Front End for ECG Acquisition

This article presents the design of a low-power ground-free (two-electrode) analog front end (AFE) for ECG acquisition. At the heart of the design is the low-power common-mode interference (CMI) suppression circuit (CMI-SC) to help minimize the common-mode input swing and prevent turning on the ESD diodes at the input of the AFE. Fabricated in a 0.18-
$\mu$
m CMOS process with an active area of 0.8
$\text{mm}^{2}$
, the two-electrode AFE can tolerate CMI of up to 12
$V_\text{pp}$
, while consuming only 6.55
$\mu$
W of power from a 1.2-V supply and exhibiting 1.67
$\mu \mathrm{V_{rms}}$
of input-referred noise in a 1–100 Hz bandwidth. Compared to existing works, the proposed two-electrode AFE thus provides a
$3\times$
reduction in power for comparable noise and CMI suppression performances.