[time-nuts] Re: Collector current that minimizes BJT noise

[Matt Huszagh]

Thanks for the reply Bob.

Bob kb8tq <kb8tq at n1k.org> writes:

> Typically, in the context of Time Nuts, the “noise” that is the issue is 
> added phase noise when amplifying a fairly high level RF carrier. In 
> that case, the 1/f noise of the device very much does matter.

No disagreement there. To be clear, the purpose of ignoring 1/f noise
was to focus the discussion somewhat, as this is quite a large topic.

> You also need pretty significant collector current to provide the
> needed ( many dbm ….) power output.

Of course. But, there are still cases where low collector current might
be relevant. For instance, in a multi-stage amplifier (eg to achieve
higher reverse isolation) you might set a higher input impedance for the
second stage and run the first stage at lower collector current. I'm not
sure yet if you'd want to do this, but it is conceivable.

Matt