cmos inverter speed

[till]

question:

using a 74HC04 for inverting a signal line should make a delay of about 6ns as datasheet tells.

If i make a cmos pair inverter from BS170/BS250, how fast will this be? how do i find how fast it is? measure some way or caslculate.

Are there better transistors i should try instead of these?

[jbokelman]

Originally posted by till
using a 74HC04 for inverting a signal line should make a delay of about 6ns as datasheet tells.

I think the HC04 propagation delay, under normal conditions, is more like 10ns. Why don't you just use faster logic?

[till]

74HC04 was the fastest i found on first look at Reichelt, and it says 6ns at 5V.

As i only need one inverter and don´t like all those unused pins i would prefer to use discrete inverter. Whats against building it from 2 Fets? How to build it discret for beeing fast?

[jbokelman]

Make your own inverter out of FETs, if you like. If I wanted a single, fast inverter without the baggage of a DIP, I'd look at a pico-gate, like the 74V1GU04. Its prop delay is 3.5ns @ 5v.

[till]

I allready made it, and i like it more than having loads of unused inverters on my board. What i want to know is how to obtain some information about the discrete inverters performance, and if there are better transistors for this purpose than BS170/BS250.

Picogates and faster ICs are no solution as long as my supplyers don´t stock them and they are not avaiable, not even as sample.

[Elso Kwak]

Hello Till,
Fairchild and Onsemi can send you one inverter per package as a sample. The latter will cost you US$ 14.99.

BTW my mail through the forum did not reach you as your server apparently did not accept it:
"The recipient does not accept mails from 'hotmail.com' over foreign mailservers".

ELSO/

[Jocko Homo]

BTW..........you know someone who has a handful of picogates........

Jocko