caa a22 4500 465739806 CHVBK 20180323111805.0 cr unu---uuuuu 170327e19900501xx s 000 0 eng 10.1007/BF02368441 doi (NATIONALLICENCE)springer-10.1007/BF02368441 Composite instrumentation amplifier for biopotentials [Elektronische Daten] [R. Pallás-Areny, J. Webster] We present the design of an instrumentation biopotential amplifier that, (a) combines the ac coupling and high input impedance of an ac-coupled buffer with the CMRR of a simple differential amplifier or a monolithic instrumentation amplifier, (b) improves the CMRR by using a potentiometer without requiring either precision resistors or high-CMRR op amps, (c) illustrates how to calculate the CMRR for differential-input stages for either differential output or single-ended output. With our approach, for the 741 op amp, the CMRR of the differential stage exceeds 126 dB at 10 Hz and 106 dB at 100 Hz, which is higher than the 90 dB of the op amp alone. This is because a potentiometer permits mismatch of the resistor ratio, which compensates for the low CMRR of the op amp. Use of the LF355 op amp, which has a wider bandwidth, yields a CMRR of 126 dB at both 10 and 100 Hz. If the second stage is an instrumentation amplifier then no adjustment is necessary. Mismatch of passive components in the bootstrapped input buffer stage decreases the CMRR from 126 dB to 112 dB at 60 Hz and decreases it further at lower frequencies, but that is not a problem for the usual power-line interference. Pergamon Press plc, 1990 Biopotential amplifiers nationallicence Differential amplifiers nationallicence Composite amplifiers nationallicence Common mode rejection ratio nationallicence Interference nationallicence A c : op-amp open loop common mode gain nationallicence A d : op-amp open loop differential mode gain nationallicence A 0 : op-amp open loop dc gain nationallicence CMRR : common mode rejection ratio nationallicence CMRR B : common mode rejection ratio for the input stage nationallicence CMRR D : common mode rejection ratio for the differential stage nationallicence CMRR IA : common mode rejection ratio for IC instrumentation amp nationallicence CMRR OA : common mode rejection ratio for the op amp nationallicence CMRR OA (0) : common mode rejection ratio for the op amp at dc nationallicence CMRR T : total common mode rejection ratio for the circuit nationallicence G c : common mode gain of second stage nationallicence G d : differential mode gain of second stage nationallicence G DC : gain from the common mode input to differential output nationallicence G DD : gain from the differential mode input to differential output nationallicence H(s) , H 1( s ), H 2( s ) : transfer function of input buffers nationallicence IMRR : isolated mode rejection ratio nationallicence k 1, k 2 : resistors' ratios nationallicence υ a υ b : buffers' output voltages nationallicence υ' a υ' b : input voltages to the op amp nationallicence υ c : common mode input signal nationallicence υ d : differential mode input signal nationallicence υ o : output voltage nationallicence υ C : common mode output signal for the input stage nationallicence υ D : differential mode output signal for the input stage nationallicence υ1υ2 : input voltages nationallicence Z C : common mode input impedance nationallicence Z CE : effective coupling impedance nationallicence αα a : resistors' ratio mismatch nationallicence β : resistors' tolerance nationallicence τ1τ2τ m τ a τ n : time constants nationallicence ω a : op-amp unity gain frequency nationallicence ω n : low-pass corner frequency for input buffers nationallicence Pallás-Areny R. División de Instrumentación y Bioingenieria Departamento de Ingenieria Electrónica, U.P.C., ETS Ing Telecom, P.O. Box 30002, 08080, Barcelona, Spain aut Webster J. Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin aut Annals of Biomedical Engineering Kluwer Academic Publishers 18/3(1990-05-01), 251-262 0090-6964 18:3<251 1990 18 10439 https://doi.org/10.1007/BF02368441 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02368441 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pallás-Areny R. División de Instrumentación y Bioingenieria Departamento de Ingenieria Electrónica, U.P.C., ETS Ing Telecom, P.O. Box 30002, 08080, Barcelona, Spain aut NATIONALLICENCE 700 1- Webster J. Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin aut NATIONALLICENCE 773 0- Annals of Biomedical Engineering Kluwer Academic Publishers 18/3(1990-05-01), 251-262 0090-6964 18:3<251 1990 18 10439 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer