At 03:14 PM 1/9/2006 +1300, you wrote:
>Thought experiment for those with time on their hands :-)
>
>Bipolar transistors are current amplifiers, so it almost always makes
>sense to operate them with base current less than collector current -
>usually much less . Some high voltage applications have forced Betas
>not much more than 1 as the switched power (HV x Ic) is >> the
>switching power Ib x Vbe.But, just sometimes, in low voltage
>applications it can be useful to have base current > collector
>current.
>
>I have just designed a circuit with a small signal PNP bipolar
>transistor with a forced Beta of about 0.5.
>
>Suggest why?

One obvious (?) purpose would be to have very low Vce (perhaps in the
single or low-double-digit mV range), and to avoid the need for a low
Rds(on) small-signal p-channel MOSFET.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
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