Amplifier circuits for driving large capacitive loads

摘要

In an amplifier for driving a large capacitive load, a boost circuit is included to improve the efficiency of the amplifier where an input to the amplifier has a small signal swing. The amplifier comprises a stack of series-connected charge-storage capacitors serving as secondary power sources. During a charging of the capacitive load, charge is obtained from voltage nodes between the stack capacitors. One or more low-voltage power supplies are connected to the capacitive load in the boost circuit. With these power supplies, during a discharge of the capacitive load, the latter appears to be charged to a higher voltage than it actually is so as to return some charge to the highest voltage node from where a portion of its charge was obtained. As a result, the power consumption in the amplifier is substantially reduced.