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Products => Test Equipment => Topic started by: DennisR on August 31, 2023, 06:41:22 am

Title: Ultra Low Noise Preamp, 40dB ,20Hz to 10Mhz
Post by: DennisR on August 31, 2023, 06:41:22 am

I'm looking for a pre-build AC coupled 40db amplifier with very low noise. I would need a range between 20Hz to 10Mhz

I'd like to measure noise in the range of 100-500µV, but my oscilloscope noise floor is around 2mV.

The Picotest J2180A-20 looks promising, but in only has a 20dB gain. 
https://www.picotest.com/products_J2180A.html (https://www.picotest.com/products_J2180A.html)

Title: Re: Ultra Low Noise Preamp, 40dB ,20Hz to 10Mhz
Post by: David Hess on September 01, 2023, 10:05:41 am

100 to 500 microvolts RMS over 10 MHz is 32 to 158 nV/SqrtHz which is not particularly demanding, and *worse* than some old 200 MHz oscilloscopes.

A Preamble DA1855 or LeCroy DA1855A does more than you need and might be suitable if you can find one.  Differential operation raises input noise by 40%, but also adds common mode rejection which removes noise.

https://w140.com/tekwiki/wiki/Preamble_DA1855

Title: Re: Ultra Low Noise Preamp, 40dB ,20Hz to 10Mhz
Post by: sonpul on September 01, 2023, 10:45:16 am

If you described your tasks in more detail, perhaps someone will share their methods, experience and equipment used.

Quote

I'd like to measure noise in the range of 100-500µV, but my oscilloscope noise floor is around 2mV.

But the J2180A costs as much as a few new oscilloscopes to suit you. Maybe it makes sense for you to buy one and there is no problem?