Switching amplifier for driving a load through an alternating-current path with a constant-amplitude, varying duty cycle signal

An amplifier includes first and second switches coupled at a junction to form a series circuit. The series circuit is serially coupled with an inductor across a source of energizing potential. A capacitor couples the junction between the switches to a load. The switches conduct alternately under the control of a duty cycle modulator. The duty cycle modulation tends to vary the amplitude of the two opposite-polarity portions of the signal appearing across the load. A clamp is coupled to the junction of the series switch circuit and the inductor. The clamp operates during a first of the two alternate switch conduction intervals to clamp the voltage across the inductor at a fixed value. Since a direct voltage cannot be established across an inductor, the voltage across the inductor during the second switch conduction interval is established by the clamp voltage and the duty cycle, and varies with duty cycle. The amplitude of the signal at the junction of the two switches varies with duty cycle variations in such a manner as to maintain the signal of one polarity across the load at a constant amplitude.