# how to amplify voltage in range mV to V

1. ## how to amplify voltage

Hi,
I need to know what type of op-amp configuration can be used to amplify the input voltage of mV to V ( a gain of 1000)

2. ## 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.

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3. ## how to amplify mv to v

Originally Posted by e_e
Hi,
I need to know what type of op-amp configuration can be used to amplify the input voltage of mV to V ( a gain of 1000)
With what precision (dynamic range), what bandwidth, what source impedance and what time scale of the measurement ?

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.

4. ## need to amplify voltage

But the op-amp I studied, like single stage OTA, cascaded, folded cascode, they only have the gain in range of 10-100 right?
So, how to get a such high gain of 1000?

5. ## amplify mv

Originally Posted by e_e
But the op-amp I studied, like single stage OTA, cascaded, folded cascode, they only have the gain in range of 10-100 right?
So, how to get a such high gain of 1000?
folded cascode op has higher gain (>60dB) than simple OTA, and it's not difficult to build such a op, refered to Martin's book or Razavi's book.

6. ## how to amplify 2 mv

A simple inverting op-amp using the ua741 op-amp from National Semiconductor will do the trick.

choose R2=1MOhm and R1=1KOhm

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7. ## 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.

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8. ## how to amplify mv

Try folded cascode, telescopic or gain boosted cascode for gain maximization.

9. ## amplify voltage from mv

You may try differential opamp AMP04.

10. ## thermal offset opamp

Originally Posted by e_e
But the op-amp I studied, like single stage OTA, cascaded, folded cascode, they only have the gain in range of 10-100 right?
So, how to get a such high gain of 1000?
With a two-stage OTA, you can get more than 1000 v/v gain.

11. ## 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.

12. ## Re: how to amplify voltage in range mV to V

easily with opamp

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13. ## 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.

14. ## how to amplify voltage in range mV to V

use the swithed capacitor amplifier for the accurate amplification

@_@

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16. ## 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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