RobG
|
The base current of a bipolar device depends on the Vce voltage. For a bipolar cascode this voltage-dependent base current limits the amount of output resistance possible. Bipolars also don't recover smoothly when their base-collector junction is forward biased.
Bipolar mirrors are lousy because of their high gm (small mismatches result in large current changes). What you wind up doing is adding degeneration resistors, which are resistors between the emitters and the power supply. If you do that and have a good biCMOS process bipolar mirrors work well.
|