A current balancing circuit for first and second lamp sets includes a
step-up transformer and a current balancer. The step-up transformer is
adapted to be coupled to a power supply for receiving an
alternating-current source power, and for generating a drive signal by
varying magnitude of the alternating-current source power. The step-up
transformer is further adapted to be coupled to the first and second lamp
sets for providing the drive signal thereto. The current balancer
includes first and second shunt transformers. Each of the first and
second shunt transformers includes primary and secondary windings that
correspond to each other in number of turns thereof. The first and second
shunt transformers are adapted to be coupled to corresponding discharge
lamps of the first lamp set. The current balancer is adapted to mirror
current flowing through the first and second shunt transformers to the
second lamp set.