Two-electrode low supply voltage electrocardiogram signal amplifier
Portable biomedical instrumentation has become an important part of diagnostic and treatment instrumentation, including telemedicine applications. Low-voltage and low-power design tendencies prevail. Modern battery cell voltages in the range of 3-3.6V require appropriate circuit solutions. A two-electrode biopotential amplifier design is presented, with a high common-mode rejection ratio (CMRR), high input voltage tolerance and standard first-order high-pass characteristic. Most of these features are due to a high-gain first stage design. The circuit makes use of passive components of popular values and tolerances. Powered by a single 3V source, the amplifier tolerates +/-1V common mode voltage, +/-50 muA common mode current and 2V input DC voltage, and its worst-case CMRR is 60 dB. The amplifier is intended for use in various applications, such as Holter-type monitors, defibrillators, ECG monitors, biotelemetry devices etc.
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