Apparatus and method for improving common mode rejection ratio using instrument amplifier

PURPOSE: An apparatus of increasing a common mode rejection ratio and a method thereof are provided to improve a common mode rejection ratio by using three instrumentation amplifiers. CONSTITUTION: A measurement amplification device comprises a first instrument amplifier(110), a second instrument amplifier(120), and a third instrument amplifier(130). The first instrument amplifier has a positive input terminal(112) and a negative input terminal(114). A signal is inputted to the first instrument amplifier through the positive input terminal and the negative input terminal. The first instrument amplifier generates an output signal by performing a measurement amplifying function for the inputted signal. The second instrument amplifier has a positive input terminal(122) and a negative input terminal(124). The third instrument amplifier has a positive input terminal(132) and a negative input terminal(134).