### Author Topic: sanity check on cascaded gain amplifier (temp co gain error)  (Read 1174 times)

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#### SArepairman

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##### sanity check on cascaded gain amplifier (temp co gain error)
« on: April 26, 2014, 04:50:34 pm »
Before I buy some parts I want to check something with you guys

if I had a two gain stages in a row. each gain stage has a gain of 10.000004  (assuming 1k/10k with 0.2ppm drift, drift in opposite directions over 1C)
so the total error is 10.000004*10.000004=100.00008

error is 0.0000799% / degree celcius

if i instead had a single stage, with 0.2 ppm resistors, of 1000 and 100000 ohm
1000*(0.2/10^6) = 0.0002 = 999.9998 ohm
100000*(0.2/10^6) = 0.02 = 100000.02 ohm

gain = 100.00004, gain error  = 0.000039%

so, if i split my gain over 2 stages rather then 1 stage my temperature coefficient error doubles?

these prices got me so anxious i need my hand held lol
* I don't care about offset error, only gain error

#### IonizedGears

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##### Re: sanity check on cascaded gain amplifier (temp co gain error)
« Reply #1 on: April 29, 2014, 10:03:18 am »
Well, yeah, you now have double the temp sensitive parts so there is twice as much deviance.  Also, make sure that one stage could go that fast to give to a gain of 100 rather than two with each a gain of 10. Essentially by using one stage rather than two gives the one stage 10 times the work.

~Ionized Gears

I am an EE student with interests in Embedded, RF, Control Systems, and Nanotech.

Smf