BIOPOTENTIAL AMPLIFIERS - Design and Development of Medical Electronic Instrumentation - page 31

TABLE 1.1 The Gain of the INA102 ICIA of
Figure 1.27 Is Jumper-Programmable According
to These Settings for JP1 and JP2
Gain JP1 JP2

1 None 2-3

10 1-6 2-3

100 2-5 2-3

1000 3-4 1-2

Figure 1.28 The components that select gain and bandpass filter characteristics (R6-R9 and
C3-C5) for the ICIA-based biopotential amplifier can be soldered onto a DIP header which is
inserted in a standard 14-pin DIP socket. A number of these DIP-header modules may be assembled
to provide an assortment of desired passband and gain characteristics.

selection and preparation of electrode placement on the subject, and by keeping the band-
pass characteristics of the biopotential ampli er as tight as possible. When connected to a

test subject, the circuit must always be powered from batteries or through a properly rated
isolation power supply. The same isolation requirements apply to the output of the ampli

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er.
To test and calibrate the unit, you will need a two-channel oscilloscope and a signal
generator. Take the following steps:

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1. Assemble the DIP header according to your requirements and install in the 14-pin
socket.
2. After verifying the connections, power the biopotential ampli

fi er circuit with a

symmetrical power supply.
3. Short both inputs (J1-2 and J1-3) of the biopotential ampli fi er to ground (J1-1,4).

gure JP1 and JP2 for a gain of 10.
4. Connect the oscilloscope's input to the output of the biopotential ampli

Con fi

fi er circuit

er's (J3-2).
5. The output signal should be stable and should present no oscillatory behavior or
drift. At very high gains, the peak-to-peak input noise of the circuit can be measured.
6. Short the inverting (J1-2) input terminal of the biopotential ampli

(J3-1) and the oscilloscope's ground to that of the biopotential ampli fi

er to the subject
ground terminal (J1-1,4), and connect these to the ground terminal of a signal

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