To expand the operation range of in-phase input in a comparatively simple configuration by respectively connecting one and the other input terminals through a DC shift circuit to one and the other input terminals of plural error amplifiers and mutually connecting the output terminals of these plural error amplifiers.

This circuit is provided with (n) pieces of error amplifiers 101-10n. Then, input terminals 1a and 1b on one side and the other side to supply signals are respectively connected through DC shift circuits 121-12n and 141-14n to the input terminals of these (n) pieces of error amplifiers 101-10n on one side and the other side. At the same time, the output terminals of these (n) pieces of error amplifiers 101-10n are parallelly connected so as to lead out output terminals 11a and 11b. Thus, the operation range of the in-phase input to this error amplifier becomes the sum of operation ranges of in-phase input to these (n) pieces of error amplifiers 101-10n and the wide operation range of in-phase input can be achieved.