Hello
My Customer had tested TPA2038D1EVM, but they says THD+N is bad ( 0.4%).
I told him the reason why may be due to output filter.
They intend to use TPA2038D1 for FY18 conference sysytem.
Q1
Is this idea correct?
where: TPA2038D1 EVM
Output filter is FB1, FB2( Ferrite Bead). http://www.tij.co.jp/jp/lit/ug/slou298/slou298.pdf
TPA2038D1 data sheet page8 Fig13: 8ohm + 33uH Gain=6dB
Q2
In data sheet Fig13, condition is L=33uH, but what is the C value for LC filter?
<Back Ground>
EVM Test Result by customer Po=50mW, THD+N Ratio=0.41%
Po=50mW THD+N Ratio=0.04%(Datasheet P8-Fig.13) <Customer's Test Setup>
/TPA2038D1YFFEVM Rev D Vdd=+5.0V, RL=8Ω, Gain=+6dB
/Audio Precision SYS2722 internal 20~20KHz filter used
/AP(Out,1kHz Sine Wave) ⇒EVM⇒ 30kHz LPF(RC) * ⇒ AP(In)
* customer reffered
http://www.tij.co.jp/jp/lit/an/sloa068/sloa068.pdf