How fast can germanium transistors compute ?
This question might receive an answer soon.
While visiting one of the few remaining electronics parts stores of Paris, I found that they have a little stock of Ge. And I got their last AF280. From the datasheets:
This transistor is particularly intended for use in mixer and oscillator circuits up to 900 MHz in diode tuned tuners.
So the intuition worked (higher number means better performance, right ?), this transistor is faster than the 500MHz AF240 (though only by 10% because its transition frequency is actually rated for 550MHz) and the datasheet claims a power gain of 16dB @800MHz (power gain of approx 40, or amplitudes 12 ?) to a 2K ohms load (compatible with an ECL gate impedance). Too bad my DDS can't go so fast, but I'll try to hack a picosecond pulse generator...
I got 13 AF280 and if I don't make mistakes, I might be able to build two NOR2 or NOR3 gates. Enough to test some logic and/or a flilp-flop :-)
It just appears now that the answer I might get is not of the kind I expected intially.
With such fast transistors, my lab tools are already too slow. I consider building a picosecond pulse generator but that won't help much.
Furthermore, if I build a globule that is clocked so fast, I have another problem : memories. Latency and bandwidth will be hard to match with the expected means and I'll have to resort to using fast silicon chips.
20170106: I found a batch of AF439, roughly equivalent to the AF280/279, so I might be able to build more than a couple of gates :-)
It's going to be fun, though, since the hFE is ">10" (http://alltransistors.com/transistor.php?transistor=21851). The frequency is rated at 400 and 800MHz depending on the sources, but this speed will be held back by poor amplification.