A current replication circuit that avoids the LEB period restriction of a
DC-DC boost converter. The DC-DC boost converter regulates an output
voltage by switching an input voltage through an inductor and a diode
using a switch controller employing current feedback control and
providing a PWM signal to control a switch coupled to the inductor. The
current replication circuit includes a current sensor, a ramp generator,
and a summing device. The current sensor samples current through the
inductor while the switch is off and provides a sample voltage indicative
of inductor current just before the switch is turned on. The ramp
generator provides a ramp voltage replicating current increase of the
inductor while the switch is on. The summing device adds the sample
voltage to the ramp voltage to develop a replication voltage used for
feedback current control by the switch controller.