An amplifier capable of driving an analog load is provided. The amplifier
can be constructed and arranged to operate as at least one circuit
selected from the group consisting of a class D amplifier, voltage
regulator, audio amplifier, servo amplifier, servo control, digital
control, switching power supply, and switching power amplifier. The
amplifier comprises a sigma delta modulator (SDM), a pulse processing
circuit, an output stage, and a feedback loop. The SDM produces a
plurality of noise-shaped output pulses based upon an input signal (e.g.,
an analog input signal) to the amplifier and an error signal. The pulse
processing circuit processes at least a portion of the plurality of
noise-shaped output pulses to ensure that each of the noise-shaped output
pulses in the portion contains an amount of energy that is as close as
possible to the amount of energy in the other pulses. The output stage is
coupled to the pulse processing circuit and has first state wherein the
output stage provides analog noise-shaped output energy pulses to a load
and a second state where the output energy delivered is essentially zero.
The feedback loop is coupled between the output stage and the SDM. The
feedback loop samples the energy provided to the load during the first
state by measuring the load during the second state and generates an
error signal based on the difference between the sampled portion of the
noise-shaped output pulses and the input signal to the amplifier.