
List of figures AN3959
4/65 Doc ID 022081 Rev 3
List of figures
Figure 1. STA381BW/STA381BWS 2.0-channel demonstration board . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 2. Schematic-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 3. Schematic-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. Top view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 5. Inner layer2 view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 6. Inner layer3 view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 7. Bottom view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 8. Block diagram of test connections with equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 9. Frequency response, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 16
Figure 10. Crosstalk, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 11. SNR, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 12. THD vs. frequency, VCC = 18 V, RL= 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 13. FFT (0 dBFS), VCC = 18 V, RL= 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 18
Figure 14. FFT (-60 dBFS), VCC = 18 V, RL= 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 18
Figure 15. THD vs. output power, VCC = 18 V, RL= 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 16. THD vs. output power at different power supplies, RL= 8 ohm, f = 1 kHz . . . . . . . . . . . . . 19
Figure 17. Frequency response, VCC = 24 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 20
Figure 18. Crosstalk, VCC = 24 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 19. SNR, VCC = 24 V, RL= 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 20. THD vs. frequency, VCC = 24 V, RL= 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 21. FFT (0 dBFS), VCC = 24 V, RL= 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 22
Figure 22. FFT (-60 dBFS), VCC = 24 V, RL= 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 22
Figure 23. THD vs. output power, VCC = 24 V, RL= 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 24. THD vs. output power at different power supplies, RL= 8 ohm, f = 1 kHz . . . . . . . . . . . . . 23
Figure 25. Temperature test 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 26. Temperature test 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 27. Output filter (BTL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 28. Differential-mode snubber circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 29. Common-mode snubber circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 30. Main filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 31. Dumping network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 32. Recommended power-up and power-down sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 33. Snubber network soldered as close as possible to the respective IC pin . . . . . . . . . . . . . . 31
Figure 34. Electrolytic capacitor used first to separate the VCC branches . . . . . . . . . . . . . . . . . . . . . . 32
Figure 35. Path between VCC and ground pin minimized in order to avoid inductive paths . . . . . . . . 32
Figure 36. Large ground plane on the top side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 37. Large ground plane on inner layer2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 38. Large ground plane on inner layer3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 39. Large ground plane on bottom side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 40. Symmetrical paths created for output stage, for differential applications . . . . . . . . . . . . . . 35
Figure 41. Coils separated in order to avoid crosstalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 42. VCC filter for high frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 43. Thermal layout with large ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 44. Processing path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 45. 2.1-channel with STCompressorTM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 46. STCompressor - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 47. STCompressor - mapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 48. STCompressor - compression ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40