Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Q&A

Comments on How building a follower satisfying rather extreme requirements.

Post

How building a follower satisfying rather extreme requirements.

+2
−1

What is your best suggestion for building a follower that would ideally satisfy the following spec:

  • frequency: from 100 Hz (or lower) to 1 GHz
  • input signal impedance: 1 Mohm
  • input signal amplitude: from 1 mV to 1V at least
  • output load to be driven: 50 Ohm.
  • The follower need not be absolutely flat (gain = 1), but actually, it is allowed to reduce the signal by a factor of 0.5.
  • some signal distortion allowed.
  • also, a small DC offset voltage of few mV can be allowed, as I am interested in the AC component of the signal.

If that is not possible, please give me the suggestion that best approaches these specs. Also, I would be happy if the part names or part numbers are indicated.

EDIT: as pinpointed by Olin Lathrop, the 1 GHz requirement is fundamentally incompatible with the 1 M Ohm input impedance requirement. So, there is no point to go further for the moment.

History
Why does this post require attention from curators or moderators?
You might want to add some details to your flag.
Why should this post be closed?

1 comment thread

General comments (5 comments)
General comments
Andy aka‭ wrote almost 4 years ago

Have you tried looking for wide bandwidth unity gain stable op-amps?

coquelicot‭ wrote almost 4 years ago

Not with those keywords. Will try and perhaps delete this question.

coquelicot‭ wrote almost 4 years ago · edited almost 4 years ago

For the moment, I've found the opa695 that is best suited, but it has 70uA input current. Also, the big 50 Ohm load is a problem.

Lundin‭ wrote almost 4 years ago

This is far from my area of expertise, but have you checked Analog Devices? They have tonnes of more or less exotic amplifiers. https://www.analog.com/en/products/rf-microwave/rf-amplifiers.html. If you for example check their "Wideband Distributed Amplifiers" they have lots of parts explicitly designed for 50 ohm, mostly with matched input/output.

coquelicot‭ wrote almost 4 years ago

@Lundin. Thank you for the link. I will have a look.