Op-amp circuits and noise at high frequency/low amplitude

In summary: No, the op amp does not "kind of work as a low pass filter." Op amps are designed to amplify signals, so they will amplify any noise present in the signal. No filtering will help.No, the op amp does not "kind of work as a low pass filter." Op amps are designed to amplify signals, so they will amplify any noise present in the signal.
  • #1
GuitarOfWar
5
0
Hi everyone.

I am tasked with amplifying an input voltage of around 1nA at anywhere between 10,000kHz to 1MHz to a sufficient amount. We've been using op-amps in multiple stages in series to amplify the signal. At our disposal we have a function generator, oscilloscope, breadboard and resistors, capacitors etc. Are there any tricks or techniques I can use to reduce the noise from the op-amps?
 
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  • #4
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GuitarOfWar said:
I can't bandpass the signal because the input is meant to be simulating particles hitting a plate at a frequency of say 10000kHz to 1MHz.

You're wrong. it sounds like you have a false idea of what bandpass filter means. The word "band" means a range of frequencies, such as 10kHz-1MHz.
 
  • #5
anorlunda said:
You're wrong. it sounds like you have a false idea of what bandpass filter means. The word "band" means a range of frequencies, such as 10kHz-1MHz.
Doesn't the op amp kind of work as a low pass filter? At frequencies about 1.5-2MHz+ the gain starts decreasing any way. Also we tried using high-pass filter with an RC circuit that only allows frequencies above 10,000kHz to pass and the amount of noise reduced wasn't dramatic. Is there any other tricks I can use to eliminate noise which aren't just using a filter or is my task limited by the type of op-amp I am using?
 
  • #6
I posted an answer in the original thread.
 

Related to Op-amp circuits and noise at high frequency/low amplitude

1. What is an op-amp circuit and how does it work?

An op-amp (operational amplifier) circuit is a type of electronic amplifier that is commonly used in various applications such as signal processing, filtering, and amplification. It typically consists of two input terminals, one output terminal, and a power supply. The op-amp amplifies the voltage difference between its two input terminals and produces a corresponding output voltage. It works by utilizing a high-gain differential amplifier with active elements such as transistors and diodes.

2. How does noise affect op-amp circuits at high frequency and low amplitude?

Noise can significantly affect the performance of op-amp circuits at high frequency and low amplitude. At these conditions, the noise signals can be amplified and add up to the desired signal, resulting in a distorted output. This can cause errors and inaccuracies in the circuit's operation and can also lead to instability and oscillations.

3. What are the common sources of noise in op-amp circuits at high frequency and low amplitude?

The most common sources of noise in op-amp circuits at high frequency and low amplitude are thermal noise, shot noise, and flicker noise. Thermal noise is generated due to the random motion of electrons in the circuit's components. Shot noise is caused by the discrete nature of electrical current, while flicker noise is a low-frequency noise that is dominant at higher frequencies.

4. How can noise in op-amp circuits at high frequency and low amplitude be reduced?

There are several techniques that can be used to reduce noise in op-amp circuits at high frequency and low amplitude. These include using low noise components, implementing proper grounding techniques, shielding sensitive components, and using filtering circuits to remove unwanted noise signals. Additionally, careful circuit design and layout can also help minimize the impact of noise on the circuit's performance.

5. What are the precautions to take when designing op-amp circuits for high frequency and low amplitude signals?

When designing op-amp circuits for high frequency and low amplitude signals, it is important to consider the potential impact of noise and take necessary precautions to minimize its effects. This can include using low noise components, selecting the appropriate op-amp with low input offset voltage and noise, and implementing proper grounding and shielding techniques. Careful consideration should also be given to the circuit's layout and design to minimize noise coupling and interference.

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