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

[GuitarOfWar]

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?

 

[anorlunda]

You already posted this question and got answers on another thread.

ttps://www.physicsforums.com/threads/op-amps-noise-and-high-frequency-low-current-input-signal.885500/#post-5568328

 

[GuitarOfWar]

You already posted this question and got answers on another thread.

ttps://www.physicsforums.com/threads/op-amps-noise-and-high-frequency-low-current-input-signal.885500/#post-5568328

I was told it should be in the EE forum. Also the answer I was given is not doable.

 

[anorlunda]

• Multiple Posting:
  Posting the same topic (or homework question) across multiple forums or multiple threads is considered spamming and is not allowed. (No cross-posting.)

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.

 

[GuitarOfWar]

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?

 

[anorlunda]

I posted an answer in the original thread.