
170 The Circuit Designer’s Companion
voltage feedback. Voltage feedback is the classic, well-understood mechanism which
we have been discussing all the way through this section so far. In current feedback, the
error signal is a current flowing into the inverting input; the input buffer’s low
impedance, in contrast to a voltage amplifier’s high input impedance, allows large
currents to flow into it with negligible voltage offset. This current is the slewing current,
and slew rate is a function of the feedback resistor and change in output voltage.
Therefore, the current-feedback amplifier has nearly constant output transition times,
regardless of amplitude. ...