how to improve TPA3118D2 THD?

cg xie

Intellectual 260 points

Other Parts Discussed in Thread: TPA3118D2

Dear Sir,

The test configration is as below and the THD test result is 0.3% (TPA3118D2 spec is 0.02%）

* TPA3118 in BD mode / BTL Output / Gain Set 36dB

* 4 OHM load

* 14.4V supply

* output 1W

* 1KHz test signal.

I want to know what will impact THD result and how to improve this. Thanks a lot.

Below is the SCH.

6663.AMP.pdf

over 12 years ago

0 user5276421 over 12 years ago

TI__Mastermind 37045 points

Hi CG,

Please check out the apps note below on the AP setup and filtering requirements. Did you use a AES-17 filter or any RC filter?

http://www.ti.com/lit/an/sloa068/sloa068.pdf

http://www.ti.com/lit/an/sloa107/sloa107.pdf

Are you testing this on a resistive 4R load? Did you add any inductor (~33uH) in series to the resistive load?

Are the output inductor and ferrite beads adding more non-linearity to the measurements?

reg,

Paul.

0 cg xie over 11 years ago in reply to user5276421

Intellectual 260 points

Hi Paul，

1. I have add filter (20Hz~20KHz) in the Audio Analyzer Setup Menu.

2. Test on a resistive 4R load, without any inductor in series to the load.

3. If the output inductor and ferrite beads impact the THD performace, how to choose the inductor and beads?

Thanks a lot.

0 Don Dapkus over 11 years ago in reply to cg xie

TI__Guru**** 189401 points

Hi, CG

Allow me to jump in here...

I think you have too many unknowns. I suggest you get a TPA3118D2 EVM, and measure the performance. Once you can duplicate the d/s data, then you can proceed to measuring your board.

The closer you copy our EVM (layout and BOM), the easier it is to meet the performance figures.

-d2

0 cg xie over 11 years ago in reply to Don Dapkus

Intellectual 260 points

I have measured the DEMO board, the THD is 0.09% (still larger than 0.02% in spec page 7/figure 2).

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how to improve TPA3118D2 THD?