Pretty! |
GaAs red LEDs weren't very bright. By adding Aluminium, Indium, Phosphorus, Nitrogen etc, new colours & higher-efficiency old colours were invented. Orange. Yellow. Green. Brighter green. Even brighter green. Really bright green. I thought that blue LEDs would never be invented. Wrong!
Nowadays, OLEDs are so efficient that they can be used for lighting and they are more efficient and longer-lasting than CFLs. I thought that OLEDs would never catch on. Wrong! The superb display on my Samsung phone uses AMOLED technology. But anyway...
What I found interesting about GaAs red LEDs was their I-V characteristic.
Pretty techy! |
I used two "strings" of red GaAs LEDs as an ultra-low-noise voltage limiter in a high-power oscillator using LDMOS MOSFETs that had just been invented by Mullard (which later became Philips). It produced 1W (+30dBm) over a frequency range of 30 to 88MHz and had a Carrier to Noise Ratio (C/N) of >190dBc/Hz @10% frequency offset. Typical RF Signal Generators of that era had a C/N of ~145dBc/Hz at that offset.
I hope that you've enjoyed this little tour around my brain!
4 comments:
This reminds me of how much I've forgotten of EE, it was mostly over my head.
It was easy to tell if my oscillator was working, as all of the LEDs were lit! I thought that it was about time I did another post based on my old job.
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