An Innovative Approach of Implementation of High Performance Low Voltage Amplifier for Biomedical Applications

In this paper, a high performance current-mode instrumentation amplifier has been proposed for low noise, low power, high CMRR and adjustable gain with an external resistor for various biomedical signal processing. The portable biomedical instrumentation has become an important part of diagnostic and treatment instrumentation, including telemedicine applications. The low voltage and low-power design tendencies are becoming more prevailing one. A two-electrode bio potential amplifier design is discussed with a high common-mode rejection ratio (CMRR), high input voltage tolerance and standard firstorder high-pass characteristic. The circuit makes use of passive components of popular values and tolerances. The modern battery cell voltages are in the range of 3–3.6V that require appropriate circuit solutions powered by a single 3V source. This innovative amplifier tolerates a 1V common mode voltage with 50 mA common mode current and 2 V input DC voltage which in turn provides a CMRR of 60 dB. The low voltage amplifier has got the applications in various systems say Holter-type monitors, defibrillators, ECG monitors, biotelemetry devices etc. This low voltage current-mode amplifier is designed using 0.18μn CMOS technology for the various biomedical applications. The amplifier circuit is based on the use of two positive current conveyors of second generation and a current differential output stage. The device exhibits high common-mode rejection ratio which is gain unaffected in a wide frequency band. SPICE simulation results are promising for high frequency medical applications.