
Audio-frequency signals and reproduction 99
latch via
/? 5
to switch back in the opposite direc-
tion. The switching frequency is determined by the
slew rate of the integrator and the amount of
hysteresis of the latch: about 50 kHz sounds plaus-
ible.
The inductor L is 100 μΗ or more; the higher
the inductance the higher the efficiency, but if it is
too large the amplifier's response will no longer be
reasonably flat up to 20 kHz. The circuit shown
provided 5 W output with less than 0.25% distor-
tion at all volume levek.
One problem with this type of amplifier is the
generation of audible difference tones due to
intermodulation between the inpu ...