The output signal from the device is also on the inner conductor, and consists of an AC voltage centred on a bias voltage of about 8 to 12 V . The output voltage is bounded at the lower end by the saturation voltage of the integrated IEPE amplifier ( typically 0.5 to 2 volts ), and at the upper end by the maximum compliance voltage of the current source ( which may be anything between about 6 and 30 volts ).
12.
Since collector emitter voltage is equal to the sum of its own base emitter voltage and the collector-emitter voltage of the first transistor, both positive quantities in normal operation, it always exceeds the base-emitter voltage . ( In symbols, \ mathrm { V _ { CE2 } = V _ { CE1 } + V _ { BE2 } > V _ { BE2 } } \ Rightarrow \ mathrm { V _ { C2 } > V _ { B2 } } always . ) Thus the " saturation " voltage of a Darlington transistor is one V BE ( about 0.65 V in silicon ) higher than a single transistor saturation voltage, which is typically 0.1-0.2 V in silicon.
