A fully integrated two-channel A/D interface for the acquisition of cardiac signals in implantable pacemakers

This work presents an input stage for a cardiac pacemaker fully integrated in 0.35-/spl mu/m CMOS technology. The system can acquire and digitize to 8 bits both atrial and ventricular electrical activity. Log-domain circuits are exploited to amplify and filter the input signal, while /spl Sigma//spl Delta/ modulation is exploited to convert it. The design is power optimized, indeed the current consumption is limited to 2.9 /spl mu/A, while the power supply ranges from 2.8 to 1.8 V. The total area is 2.2 mm/sup 2/ and experimental data prove correct filtering and a total dynamic range of at least 47 dB.