SiRFatlasV
Audio Hardware Design Guide
January, 2010 SiRF Design Guide – Proprietary and Confidential 2
Table of Contents
Introduction ................................................................................................................... 1
Audio Output Path......................................................................................................... 3
Audio Output Path......................................................................................................... 3
DigDAC Overview .........................................................................................................................3
Application Information..................................................................................................................4
Speaker.............................................................................................................................. 4
Headphone......................................................................................................................... 6
Audio Input Path............................................................................................................ 8
Pre-amplifier ................................................................................................................................. 8
SAR ADC...................................................................................................................................... 8
Application Information..................................................................................................................9
Setting the AGC Threshold (R5 and R7) .............................................................................9
Input Capacitor (C4) ........................................................................................................... 9
Power Supply .....................................................................................................................9
RC Buffer ......................................................................................................................... 10
PCB Layout ...................................................................................................................... 10
Performance and Measurement .................................................................................................. 10
Terminology................................................................................................................. 11
List of Figures
Figure 1: DigDAC Block Diagram............................................................................................................. 3
Figure 2: Speaker Circuit ......................................................................................................................... 4
Figure 3: Frequency Response of RC Filter .............................................................................................5
Figure 4: Headphone Circuit ....................................................................................................................6
Figure 5: Frequency Response of Headphone RC Filter .......................................................................... 7
Figure 6: Input Audio Chain .....................................................................................................................8
Figure 7: Pre-amplifier Circuit ..................................................................................................................9
Figure 8: A-weighted Filter Frequency Response................................................................................... 11
