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Constant current source with OTA (Read 3060 times)
mikeharvey
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Constant current source with OTA
Nov 30th, 2003, 5:59pm
 
Hello,

I am trying to design a constant current source for a bioelectrical impedance measurement system (final class project). I need 800 microAmps (RMS maximum) at 50 kHz, and I am working with supply voltages of +/- 5 Volts.

A friend suggested using an operational transconductance amp (OTA) such as the CA3080 or NE5517 to construct a VCCS. The datasheets for these parts don't show how to construct a simple constant current source.

Any ideas for the current source (with or without OTAs) would be a great help.

Thanks,
Mike
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okguy
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Re: Constant current source with OTA
Reply #1 - Feb 8th, 2004, 7:48am
 
In IC there is no way to design a built-in current source. Embarrassed
You need to use an accurate bandgap-based design and an external accurate resistor (1% or less).

OkGuy?

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