Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Driving LED at 60 MHz

Status
Not open for further replies.

iamalearner

Newbie level 5
Joined
Mar 22, 2004
Messages
9
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
109
Hi

I need to design an LED driver circuit at a frequency of 60 MHz. The LED output light modulated at 60 MHz will be used to excite a sensor and then the light reflected from the sensor will be converted into current for further processing.

Any ideas for driving LED at 60 MHz? I want to keep the current consumption low too.

Thanks
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
48,924
Helped
14,335
Reputation
28,934
Reaction score
13,083
Trophy points
1,393
Location
Bochum, Germany
Activity points
282,298
It's easy to drive the LED with a transistor current source or simply through a resistor. But you should consider that many
LEDs have cut off frequencies around 10 or 20 MHz, so the modulation depth at 60 MHz will be poor.
 

karesz

Advanced Member level 5
Joined
Apr 13, 2008
Messages
2,332
Helped
327
Reputation
654
Reaction score
52
Trophy points
1,328
Location
EU
Activity points
14,601
Hi iamalearner,

What kind of wavelength do you need please?
My be a(NIR) VCSEL will be better for your goal?


K.
 

iamalearner

Newbie level 5
Joined
Mar 22, 2004
Messages
9
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
109
karesz said:
Hi iamalearner,

What kind of wavelength do you need please?
My be a(NIR) VCSEL will be better for your goal?


K.

Hi
The LED used is yallow/amber (590 nm) wavelength. What is VCSEL?
- jeet
 

karesz

Advanced Member level 5
Joined
Apr 13, 2008
Messages
2,332
Helped
327
Reputation
654
Reaction score
52
Trophy points
1,328
Location
EU
Activity points
14,601
Hi -jeet,

VCSEL= Vertical Cavity Surface Emitting Laser.
Usually needs relative smaller Current & the most positive data: Profile of the light-ray is equivalent with the "Top Electrode" from Chip.
This is usually a circle, the convergence is practically optimal too(has very strong parallel light & needs no collimation...)
Please check it (for example):
https://www.opticsinfobase.org/abstract.cfm?uri=ol-32-19-2831
https://en.wikipedia.org/wiki/Vertical-cavity_surface-emitting_laser
https://www.wsi.tum.de/Research/Ama.../SurfaceEmittingLasers/tabid/110/Default.aspx
In Europe are the best (research)sources:
CSEM, OSRAM, Uni Ulm, ETH Zürich, Uni Stuttgart; Uni Chemnitz...

What is your application please?

If you tell "I have LED to pulse-drive with 60MHz"; it means for me=fiber driving or spectrometry & comes the question:
You must have really yellow light , or can be infrared to?...
You can by (today) VCSEL from ca. 700 nm up to ca. 4-5um.
K.

Added after 47 minutes:

Hi,

You can check that too:
www.analog.com/static/imported-files/application_notes/AN_634.pdf

This has relative good/perfect controlling/stabilization, but my be you dont need to build so precise circuits?
Than you can take a simple High-Speed AC-MOS gate!:))
They has up to +/-24 mA driving capability and if you need more current, you can coppel it more time parallel and its packages are smallest SMD...
www.fairchildsemi.com/ds/NC/NC7WZ17.pdf

I soluted a project ca. 9 years ago with some similar type from Toshiba, & TI for 40MHz Clks, there worked over 8 years in very special field....

If you have power (or current) problems is important to know, Laser-diodes need usually up to 100-200 mAmps_ in opposite VCSEL at 5-20mAmps & LEDs at 50+/_20mAmps- or so...
K.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top