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A controlled-current inverter can be regarded as an amplifier of an ac current signal: the direct current input is proportional to the magnitude of the desired ac output and the thyristor gating signals correspond to the desired frequency and phase of the output. The actual output is attenuated and phase-shifted by amounts that depend on the frequency; the inverter has a transfer function that can be plotted as a Bode diagram. Such a transfer function is developed for the simplified special case of a purely inductive load. Below a certain frequency, the gain is almost constant, but the phase shift varies from 0 to 180??. Above that frequency, the gain drops rapidly, but there is no further phase shift.