The Circuit Below Uses Ad620An Instrumentation

Question

The circuit below uses AD620AN instrumentation amp and allows the use of a single power supply: a…

The circuit below uses AD620AN instrumentation amp and allows
the use of a single power supply: a 9V battery.

The gain of the AD620AN chip is set by the resistor across the
pins G- and G+, and is given by G = 1+ 49.4kΩ / RG so we
have set the gain to be approximately 50 by setting RG
as 1K. This, coupled with the back end op-amp gain of 24 will
result in a combined gain of 1,200. This will amplify the mV level
ECG signal to the level of a few volts.

A)Find the transfer function of the filter network. To
do this properly requires a network analysis. I encourage you to do
that, but at least, make a sketch of the LogLog transfer function
showing the slope of the low, middle and

high-frequency regions. You may also use a
model using the online circuit analysis tool PartSim.

You should find that you have a bandpass filter that includes
the relevant frequencies in the ECG. Find the low and
high-frequency 3dB voltage cutoffs. This is where the voltage has
decreased by 50%.
B) What do you think the 0.1μF capacitors across the power
supply battery is for?

C) Why does the voltage follower providing circuit
ground have a 47W resistor in series with its output?

Vcc Vcc Black 47K 47K 1K Ou 680K Red Green 75K 33K Vcc Vcc Spld Power Followve 47K

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