How is led output modulated

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Save my name, email, and website in this browser for the next time I comment. Notify me of follow-up comments by email. Notify me of new posts by email. Request a Tutorial. Circuit Test To test the circuit, a square wave with amplitude of 5V was fed into the input from a signal generator. Conclusion The maximum obtainable bandwidth is limited by the bandwidth of the LED. No Comments Jul 4, Embed Size px.

Start on. Show related SlideShares at end. WordPress Shortcode. Next SlideShares. Download Now Download to read offline and view in fullscreen. Download Now Download Download to read offline. Priyanka Anni Follow. General Electric. Mcrowave and Radar engineering. Reasons of Perception Failure. Product life cycle with example. Writing first C Program.

DSP Memory Architecture. Microstrip patch. Horn antenna. What to Upload to SlideShare. Related Books Free with a 30 day trial from Scribd. Uncommon Carriers John McPhee. The Art of War Sun Tsu. Related Audiobooks Free with a 30 day trial from Scribd. Elizabeth Howell. This is effectively a current-pulse-shaping circuit, and you'll find more if you search on "nanosecond pulsed LEDs". Sign up to join this community. The best answers are voted up and rise to the top.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Ask Question. Asked 10 years, 4 months ago. Active 2 years ago. Viewed 16k times. I know that a laser-diode can be modulated much faster.

Bjorn Wesen. Bjorn Wesen Bjorn Wesen 1 1 gold badge 4 4 silver badges 11 11 bronze badges. Add a comment. Active Oldest Votes. If you need to go over Mhz, you will need to add anti-saturation Schottky diodes. BarsMonster BarsMonster 3, 4 4 gold badges 41 41 silver badges 78 78 bronze badges.

So due to that in DVD-RW drives for example this approach is used - laser is never switched off, but in "off" state it's power is significantly lower. Olin Lathrop Olin Lathrop k 36 36 gold badges silver badges bronze badges. I'm pulling 2A In this case we are switching current, not voltage. A saturated BJT takes a while to turn off because there are lots of extra minority carriers in the base. They hang around after the base current is shut off, causing conduction until eventually used up.

A BJT never saturates in emitter follower mode, so can turn off quickly. No, a emitter switched bipolar would not be appropriate here. When that link dies your answer becomes useless. Con: carefully chosen values needed - otherwise destructive summary: For high-performance LEDs and driver design, optical rise times can be as short as 1.

Most LEDs have slower turn-off times. Here with careful design 2. It is often a good idea to have a small few percent of peak drive current pre-bias current to improve dynamic response and so the LED never gets reverse biased. DKNguyen