From: Jim Thompson
Subject: Re: connection between low currents and high phase shifts?
References: <firstname.lastname@example.org> <email@example.com>
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Date: Sun, 29 Sep 2002 15:32:10 GMT
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On 29 Sep 2002 07:14:47 -0700,
firstname.lastname@example.org (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 |
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