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• Faster and smaller

  Yann Guidon / YGDES • 03/26/2017 at 09:17 • 0 comments

  In the past months, I have been collecting ultra-fast bipolar transistors : BFR96, BF970, BFG425W, and an ample supply of MMBTH81.
  

  Lately I found an even faster reference, even cheaper, even more integrated :
  

  One of these SOT363 chips (like, SOT23 with 6 pins) can make a differential pair. 4 of them make a flip-flop.

  The BFS480 and the MMBTH81 make great parts for a fast, compact, bipolar processor...
  

• Low-Voltage, Complementary Bipolar Logic

  Yann Guidon / YGDES • 01/10/2017 at 07:29 • 6 comments

  @Ted Yapo suggested a very unusual circuit in @esot.eric's thread

  https://hackaday.io/project/18868-improbable-secret-project/log/50780-open-collector-fail-the-atx-power-switch-saga-continues#j-discussions-title
  

  Soon enough, he tried the circuit and created #CBJT Logic !

  I found out that Baker (of diode clamp fame) had explored this kind of circuit:

  And tonight, Ted tried some of the enhancements, which reduced the consumption and increased the speed !Speeding Up the NOT Gate

  The sweet spot seems to be between 1V and 1.1V with approximately 10ns of propagation time per inverter, and a not-too-high current draw...
  

  ---

  I am very tempted to play with this kind of gates for this project but experience with the other technologies show that a critical gate is the MUX2 (and MUX4) which are not trivial to design with this method. I should investigate "pass gates" made of NPN and PNP transistors...

• Inventory

  Yann Guidon / YGDES • 01/06/2017 at 09:30 • 3 comments

  (20170326) (rev 20200524) The germanium inventory is there
  

  So far, my silicon stocks are:

  Reference	Pol.	Ft(Hz)	U(V)	I(mA)	P(mW)	hFE	Fab	Qty
  BC549C	NPN	250M	30	100	625	400..800	CDIL	14500
  BC550C	NPN	250M	45	100	625	400..800	CDIL	2000
  BC559C	PNP	250M	30	100	625	400..800	CDIL	5000
  MMBTH81	PNP	600M	20	50		60	Fairchild	9000
  KSP10/ MPSH10	NPN	650M	25		350	>60	Fairchild	1500
  BF970	PNP	1G	30	30			Philips	200
  BF1009SZ	N-ch	1F	9	10			Infineon /Siemens	30
  BFR96	NPN	3.2G	15	75				170
  BFG425	NPN	3G?	4.5	30	135		NXP	200
  BFS480	NPN	7G?	8	10		100 (30..200)	Infineon /Siemens	4800 (+?)
  BFP420	NPN	25G	4V	60	200	60..130	Infineon /Siemens	100 (?)
  2N2369A	NPN	500	15	200	360	20..120	MOT(?)	50
  PMBT2369	NPN	500	15	200	250	20..120	Philips	9000

  Note: Ft (transition frequency) is often misleading:
  

  • For the KSP10 it's given as the "Current Gain Bandwidth Product", the part is tested up to 100MHz only (with some plots up to 1GHz).
  • The BFG425 is given as a "25GHz" part but the datasheet gives data tested up to 3GHz.

  Why a PNP in the middle of the NPN ? Because of Complementary ECL : it must be possible to "pack" some gates together to form a circuit with alternating polarities, save some time and gates, and power too. For example the BFS480 could be paired with the MMBTH81 (though the speed disparity might not be a great choice)

  I stumbled upon a stock of 2N2369, they might as well be included in this inventory "for scientific purposes". https://hackaday.io/project/8449-hackaday-ttlers/log/177581-my-own-try-at-a-ringo9-with-2n2369a uses some of them and I tested the 5ns rise time with few efforts (it can go faster with more efforts).
  

  Note: some BC549C are already gone to contribute to #The Cardboard Computer :-)

  20200521 : added the PMBT2369 and the BFP420

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