The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: firstname.lastname@example.org (Jorge Omar)
Subject: Re: Diodes as collector load?
Date: 3 Sep 2002 05:38:10 -0700
NNTP-Posting-Date: 3 Sep 2002 12:38:10 GMT
I will try the Vbe multiplier solution and compare distortion.
Re transistors - the ZTX1048 is a 5A TO-92 super beta device...
Back in '75 I've used a VHF one (BF200), which also had very low
Any suggestion for lower noise (and low distortion)?
Win Hill wrote in message news:...
> Jim Thompson wrote...
> >email@example.com (Jorge Omar) wrote:
> >| Re gain - 10 is enought for most decent phono inputs, and easily
> >| achievable with a string of 10 diode connected transistors of same
> >| type as the gain one.
> > I've designed variable gain amplifiers using "diodes" as loads
> > (everything was differential) and controlling gain by current
> > diversion. [ snip ]
> > For those of you not conversant with I/C techniques the use of diode
> > loads allows larger signal-handling (less distortion) in the input
> > differential-pair without using resistors.
> Right on. The transconductance gain of an un-degenerated common-
> emitter stage is qIc/kT, which creates considerable distortion into
> a fixed resistor R_L. On the other hand the resistance of a diode-
> connected transistor is kT/qIc, which nicely cancels the distortion,
> yeilding a gain of 1x. Ten transistor-diodes in series would give a
> gain of 10x, as would a single-transistor load, if its base was fed
> from its collector via a 9:1 resistive divider. Jim, what's your
> approach to retain a good noise figure for the first stage?
> - Win
> - Win
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup