Tr i p ath Technol ogy, I n c. - Techni cal I n for m ati on

4

EB-TA2022 – Rev. 1.0/03.02

Performing Measurements on the EB-TA2022 Version 4.0

The TA2022 operates by generating a high frequency switching signal based on the audio input. This

frequency of the switching pattern is spread spectrum in nature and typically varies between 100kHz

and 1MHz, which is well above the 20Hz – 20kHz audio band. The pattern itself does not alter or

distort the audio input signal, but it does introduce some inaudible components.

The measurements of certain performance parameters, particularly noise related specifications such

as THD+N, are significantly affected by the design of the low-pass filter used on the output as well as

the bandwidth setting of the measurement instrument used. Unless the filter has a very sharp roll-off

just beyond the audio band or the bandwidth of the measurement instrument is limited, some of the

inaudible noise components introduced by the TA2022 amplifier switching pattern will degrade the

measurement by including out of band (audio) energy.

One feature of the TA2022 is that it does 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

degrade frequency response. The EB-TA2022 has a simple two-pole output filter with excellent

performance in listening tests.

(See Application Note 4 for additional information on bench testing)

Contact Information

TRIPATH TECHNOLOGY, INC

2560 Orchard Parkway, San Jose, CA 95131

408.750.3000 - P

408.750.3001 - F