Tripath Technology, Inc. - Preliminary Information
The measurements of certain performance parameters, particularly those that have anything to do with
noise, like THD+N, are significantly affected by the design of the low-pass filter used on the output of the
TDA1400 and also the bandwidth setting of the measurement instrument used. Unless the filter has a
very sharp roll-off just past the audio band or the bandwidth of the measurement instrument ends there,
some of the inaudible noise components introduced by the Tripath amplifier switching pattern will get
integrated into the measurement, degrading it.
Tripath amplifiers do not require large multi-pole filters to achieve excellent performance in listening tests,
usually a more critical factor than performance measurements. Though using a multi-pole filter may
remove high-frequency noise and improve THD+N type measurements (when they are made with wide-
bandwidth measuring equipment), these same filters can increase distortion due to inductor non-linearity.
Multi-pole filters require relatively large inductors, and inductor non-linearity increases with inductor value.
23
TDA1400 – Rev. 0.65/KLi/02.06
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
