From: Jim Thompson
Subject: Re: connection between low currents and high phase shifts?
References: <email@example.com> <firstname.lastname@example.org>
X-Newsreader: Forte Agent 1.91/32.564
Date: Sun, 29 Sep 2002 15:32:10 GMT
NNTP-Posting-Date: Sun, 29 Sep 2002 11:32:10 EDT
Organization: Cox Communications
On 29 Sep 2002 07:14:47 -0700,
email@example.com (Ron J.),
In Newsgroup: sci.electronics.design,
Entitled: "Re: connection between low currents and high phase
Wrote the following:
|Thanks for the info, guys. I still can't see how darlington pairs
|will oscillate though. There aren't enough capacitors in there to
|cause this much phase shift. That statement from H&H about instability
|in these compound transistors is really confusing.
Most bipolar transistors will exhibit *negative* input impedance at
the base when the emitter has a capacitive load. The operating
current at which this occurs is dependent on the doping levels and
"structure" (layout and base thickness) of the device. It's most
often a problem with very high fT devices, such as those seen in
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
For proper E-mail replies SWAP "-" and "_"
I love to cook with wine. Sometimes I even put it in the food.