Manuals / Texas Instruments / Home Audio / Stereo Amplifier

Texas Instruments APA100 manual Gain and Phase Response, Signal-to-NoiseRatio SNR

Models: APA100

1 42

Download 42 pages 18.78 Kb

Page 40

Gain and Phase Response

Gain and Phase Response

5.4 Gain and Phase Response

The APA100 is a closed−loop, class-D audio power amplifier with an LC output filter. The output filter and the 39-kHz loop bandwidth limit the bandwidth of the APA100 reference design. The gain versus frequency curve is shown in Figure 5−8. The 4- Ω curve rolls off sooner than the 8-Ωcurve.

Figure 5−8. APA100 Gain vs Frequency With 4- W and 8-WLoad

Gain − dB

40

8 W

35

30

25

4 W

20

15

10

5
0	100 200	1 k 2 k	10 k 20 k
20

f − Frequency − Hz

5.5 Signal-to-Noise Ratio (SNR)

The APA100 has low noise and a wide output swing. The noise does not increase with output power making the signal-to-noise ratio (SNR) just before clipping good for this type of amplifier. The noise was measured with an A-weighted filter to be 350 ∝V rms. The amplifier can output 19 Vrms. This makes the SNR 95 dB at 19-Vrms output.

5-6

Image 40

Texas Instruments APA100 manual Gain and Phase Response, Signal-to-NoiseRatio SNR

Contents

Audio Power Amplifiers User’s GuideAPA100 AugustProducts IMPORTANT NOTICEApplications How to Use This Manual Read This FirstAbout This Manual Information About Cautions and WarningsRelated Documentation From Texas Instruments FCC WarningData Sheets This is an example of a warning statementContents Figures TablesEVM Overview ChapterPage Topic1.2 Power Requirements 1.1 Features1.2.1Supply Voltage EVM Basic Function/Block Diagram 1.3 EVM Basic Function/Block DiagramEVM Overview EVM Basic Function/Block Diagram FeedbackIntegrator TLV2464PCB Design SchematicChapter Page2.1 PCB Layout 2.1.1Split Ground Plane2.1.3Analog Section Layout 2.1.2H-BridgeLayoutFigure 2−2. APA100 Split Plane Bottom Layout 2.1.4PCB Layers Figure 2−3. Top Copper and SilkscreenFigure 2−4. Bottom Copper and Silkscreen Figure 2−5. Drill DrawingPCB Layout PCB DesignTable 2−1. Parts List 2.2 Bill of MaterialsBill of Materials Schematic 2.3 SchematicPCB Design Page EVM Operation ChapterPage Topic3.1 Quick Start Figure 3−1. Quick Start Module Map3.2 Power−Up/Down Sequence 3.3 Reset Button/Mute3.4 Error Signals Table 3−1. TAS5111 Error Decoding3.5 Changing the Gain Technical Information ChapterPage Topic4.1 Feedback System Design Figure 4−1. APA100 Block DiagramPhase Margin + 180 Phase at Fc Figure 4−4. APA100 Integrator Design Closed−loop gain + 1.5 0 C10 V1 1 0 4.2 TPA2001D1 Class-DModulator Figure 4−7. TPA2001D1 Block Diagram TPA2001D1 Class-DModulatorCh1: 3V/Div Ch2: 3V/Div Ch3: 3V/Div Ch4: 1V/Div t − Time −4.4 TLV2464A Gain Setting and Feedback 4.3 TAS5111 H-Bridge4.5 LC Filter Figure 4−9. APA100 Output Filter4.6 Thermal Table 4−1. TAS5111 Thermal TableAs an indication of the importance of keeping the thermal grease layer thin, if the thermal grease layer increases to 0.002 inch thick, the required heatsink thermal resistance changes to 2.4C/W Measured Results ChapterPage Topic5.1 Total Harmonic Distortion + Noise Total Harmonic Distortion + NoiseTotal Harmonic Distortion + Noise Measured Results5.2 Output Power Output PowerEfficiency 5.3 EfficiencyMeasured Results 5.5 Signal-to-NoiseRatio SNR 5.4 Gain and Phase ResponseGain and Phase Response Supply Ripple Rejection 5.6 Supply Ripple RejectionMeasured Results