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24th April 2007, 17:16 #1
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how to amplify voltage
Hi,
I need to know what type of opamp configuration can be used to amplify the input voltage of mV to V ( a gain of 1000)

24th April 2007, 17:32 #2
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mv to v amplifier
Any real operational amplifier has two major problems:
1. offset voltage
2. thermal offset drift
The offset voltage is found at the output of the amplifier, magnified with the gain
when the input voltage is zero. Example: input zero mV, offset +3mV, gain 1000, configuration inverter. The output voltage will be 3x1000=3000mV = 3V in the absence of any input voltage!
The thermal offset drift is adding to the offset voltage. Example: 15uV/C will add 15uV to any celsius degree temperature modification, magnified also with gain. At 20C above ambiant temperature (meaning +40C) the output will be 15uV x 20 x 1000 = 300mV
Conclusion: the output of an operational amplifier in inverting configuration may have 3000mV +/300mV at 40C and ZERO input voltage.
You must choose either a very low offset/low thermal drift OA and use AC magnification, or use two cascaded OA and either DC with offset compensation or AC magnification.

24th April 2007, 17:32

24th April 2007, 18:51 #3
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how to amplify mv to v
Originally Posted by e_e
For example if input noise of say 100 nVrms/rtHz is acceptable and the signal bandwidth is within of kHz range, then some can use chopper stabilized (zero drift) OP, like for instance TLC2654, what insures good long time stability.

25th April 2007, 02:23 #4
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need to amplify voltage
But the opamp I studied, like single stage OTA, cascaded, folded cascode, they only have the gain in range of 10100 right?
So, how to get a such high gain of 1000?

25th April 2007, 02:48 #5
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amplify mv
Originally Posted by e_e

25th April 2007, 03:17 #6
how to amplify 2 mv
A simple inverting opamp using the ua741 opamp from National Semiconductor will do the trick.
choose R2=1MOhm and R1=1KOhm

25th April 2007, 05:17 #7
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circuit to amplify 20 mv
telescopic and folded cascode Ota will provide gain more than 60db(1000). but in telescopic the output range will be less.

25th April 2007, 05:17

25th April 2007, 07:47 #8
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how to amplify mv
Try folded cascode, telescopic or gain boosted cascode for gain maximization.

5th May 2007, 21:36 #9
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amplify voltage from mv
You may try differential opamp AMP04.

6th May 2007, 14:37 #10
thermal offset opamp
Originally Posted by e_e

6th May 2007, 15:42 #11
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Re: how to amplify voltage in range mV to V
use instrument amplifier u can vary the gain in instrument amplifier. it is mainly for this purpose. Some companies like AD(analog devices),TI(texas instruments are offering this instrument amplifier ic packages.

7th May 2007, 14:37 #12
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Re: how to amplify voltage in range mV to V
easily with opamp
1 members found this post helpful.

8th May 2007, 07:32 #13
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how to amplify voltage in range mV to V
simple two stages CMOS opamp may esaily supplymore than 80dB(10000) in 0.6 process. one stage normally 40dB, folded cascode normally 60dB.
SO , it is depend on what process you use and other characteristics you want.

8th May 2007, 07:32

9th May 2007, 06:51 #14
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how to amplify voltage in range mV to V
use the swithed capacitor amplifier for the accurate amplification

20th August 2008, 05:33 #15
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how to amplify voltage in range mV to V
@_@

20th August 2008, 12:56 #16
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how to amplify voltage in range mV to V
maybe you need a two or three stage opamp or use gain boosting to boost your open loop gain >> 60dB.
Also determine how accurate you want your gain to be.
60dB of gain +1% requires an open loop gain of 100dB. So if your signal bandwidth is 1kHz you would need an 100MHz opamp with an open loop gain >100dB to obtain a +1% 60dB over 1kHz. That's hard for an opamp.
60dB of open loop gain in a 60dB gain setting would lead to 54dB closed loop gain.
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