Low noise, precision amp?

In summary, the conversation is about building a circuit with a gain of 300 and a bandwidth of 0.5Hz to 120Hz for a small AC input. The circuit needs to be low-noise, high-precision, and reliable. The OP is looking for references and schematic examples to help with the design. They have been recommended the AD820, AD822, and AD824 op amps and are looking for a circuit diagram for the best results. The conversation also mentions the importance of considering the impedance of the source and suggests using multiple amplifiers in parallel to reduce noise. Some suggested amplifiers are the OP-07, OP-27, and OP-627.
  • #1
juming
45
0
help!
with building a circuit. i need a gain of 300 (not exact, but somewhere around there, 200-500) for a small signal (typ. 0.1mV to 5mV) AC input with a bandwidth from 0.5Hz to 120Hz. I need it low-noise, with high precision and reliability... has anyone got a reference for any sort of help to design with schematic examples etc? :confused:

I was recommended the AD820, AD822 (dual), and AD824 (quad) op amps as they are apparently precision, very low noise amplifiers. Can someone help with a circuit diagram for connecting one or several of these for the best results?
Thanks

err... and low power too... forgot about that, its going to be battery operated... if i can't get one
 
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  • #2
You could check out Analog Devices data sheet and applications notes. A quick Google search always helps.
http://www.analog.com/en/prod/0,,759_786_AD822,00.html" [Broken]
 
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  • #3
You will probably want a multi-stage amplifier. Usually you get a very low-noise low-power preamp and then follow it with a beefier power amplifier. At least that is what we do in MRI. The total SNR is pretty sensitive to the noise figure of the preamp, and not very sensitive to the noise figure of the main amp.

-Dale
 
  • #4
juming said:
help!
with building a circuit. i need a gain of 300 (not exact, but somewhere around there, 200-500) for a small signal (typ. 0.1mV to 5mV) AC input with a bandwidth from 0.5Hz to 120Hz. I need it low-noise, with high precision and reliability... has anyone got a reference for any sort of help to design with schematic examples etc? :confused:

I was recommended the AD820, AD822 (dual), and AD824 (quad) op amps as they are apparently precision, very low noise amplifiers. Can someone help with a circuit diagram for connecting one or several of these for the best results?

The choice of the amplifier will be determined also by the source of the signal to be amplified. Apparently, bandwidth is no issue. But what's the impedance of the source ? You are actually only limited in noise performance if the impedance of the source is rather high. Otherwise, there is a cheap trick to lower the noise in the output: connect several amplifiers in parallel to the same source (this can only be done if the amplifier impedance / number of amplifiers is still higher than the impedance of the source of course), and take the average of the outputs of all the amplifiers. The average signal will be equal to the signal of one amplifier (them being all identical), but the average of the different (independent) noises will of course go down (by about sqrt(number of amplifiers)).

A few good operational amplifiers to consider:
OP-07, OP-27, OP-627, ...
but it really depends upon the application.

cheers,
Patrick.
 

1. What is a low noise, precision amp?

A low noise, precision amp is an electronic amplifier that is designed to minimize unwanted noise and accurately amplify a signal with high precision.

2. What are the benefits of using a low noise, precision amp?

The benefits of using a low noise, precision amp include improved signal quality, increased accuracy in measurements, and reduced interference from external sources.

3. What are some common applications of a low noise, precision amp?

Low noise, precision amps are commonly used in scientific and medical instrumentation, audio equipment, and telecommunications systems where accurate signal amplification is crucial.

4. How does a low noise, precision amp differ from a regular amplifier?

A low noise, precision amp is specifically designed to minimize noise and accurately amplify a signal, whereas a regular amplifier may have a higher noise level and may not be as precise in its amplification.

5. What factors should be considered when selecting a low noise, precision amp?

When selecting a low noise, precision amp, factors such as input and output voltage range, bandwidth, gain, and input impedance should be considered to ensure the amp is suitable for the specific application.

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