A solution for linearity, stability and frequency bandwidth in PAM electrocutaneous stimulators' isolation interface

This paper introduces a novel method to isolate low-level from high-voltage circuits and/or channels of PAM electrocutaneous stimulators in neuromuscular electrical stimulation (NMES). The method avoids problems of linearity and polarization stability of optocouplers and narrow bandwidth of isolation amplifiers. Its main parameters are: carrier frequency of rectangular pulses up to 1 MHz and maximum modulating signal (elliptical or triangular envelopes) of 50 kHz. The circuit has low drift, high-voltage isolation, low-power consumption, requires few components, is battery-operated and ideal for microcomputer interface-based applications.