Biomedical Engineering Reference
In-Depth Information
+15VISO
+15VISO
+15VISO
D1
1N4007
IC1A
TL074
3
2
C1
.01uF
+15VISO
J1
D4
1N4007
IC1C
TL074
10
9
4
R1
I
1
J3
+
4
1
R3
1
-
+
Chest
Electrode
8
330K
D2
1N4007
-
Right Arm
Electrode
11
330K
D5
1N4007
11
-15VISO
C2
.01uF
-15VISO
-15VISO
-15VISO
I
+15VISO
+15VISO
+15VISO
+15VISO
IC1B
TL074
SW1
D3
1N4007
I
D6
1N4007
IC1D
TL074
12
13
II
J2
ECG+
R2
4
J4
III
4
R4
1
5
6
+
CHEST
7
1
RA
+
14
RA
-
ECG-
Left Arm
Electrode
330K
D4
1N4007
LA
-
Left Leg
Electrode
330K
D7
1N4007
WCT
11
11
SW ROTARY 2P-4W
-15VISO
-15VISO
-15VISO
-15VISO
+15VISO
+15VISO
D9
1N4007
IC2A
8
-15VISO
J5
3
2
R5
+
1
1
-
I
330K
R8
IC2B
TL072
C4
.01uF
Right Leg
Electrode
D10
1N4007
TL072
4
33.2K
4
I
6
R7
-
+
C3
7
R9
-15VVISO
5
-15VISO
49.9K
R6
10M
33.2K
100pF
8
R10
C5
.01uF
33.2K
+15VISO
I
Wilson Central Terminal
Figure 2.34
This four-lead ECG amplifier separates and independently processes the ECG and pacing pulse artifact signals. The Wilson
central terminal is synthesized by R8-R10 together with IC2B and is used for right-leg driving after being inverted IC2A. SW1 selects the
lead to be amplified by instrumentation amplifier IC3 of Figure 2.35.
chest electrode. The level of this signal is closely related to the common-mode potential
seen by the limb electrodes. As such, it is used to reduce common-mode interference by
driving the right-leg electrode through inverting ampli
er IC2A.
SW1, a two-pole four-position rotary switch with insulated shaft and 5-kV contact-to-
case insulation rating selects which bu
fi
ered signals are presented to the inverting and non-
inverting inputs of instrumentation ampli
ff
fi
er IC3 of Figure 2.35. The
bipolar limb leads
are obtained as follows:
•
Lead I:
tracing of the potential di
erence generated by the heart between the left and
right arms, where the left arm (L) is the noninverting input and the right arm (R) the
inverting input
ff
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