Transcript DAC_Smith_Wanga

Audio DAC
Matt Smith
Alfred Wanga
CSE598A/EE597G
Analog-Digital Mixed-Signal CMOS Chip Design
Spring 2006
Digital Audio
Digital audio has become widespread in home/consumer electronics
Portable Music Players
(CD, SACD, MP3)
Home Theater Systems
(DVD, Optical Interconnects)
PC Audio
(Sony/Philips Digital Interface Format)
Design Philosophy - Goals

High Quality Audio Applications
 Accurate
Reproduction
 Low Noise

Versatile
 Support
for Standard Sampling Rates
 Specifications that allow use in Various Audio
Applications
Figures of Merit

Sampling Rate
 Support

Bit Depth
 Finer

common sampling speeds (96kHz)
Resolution → Better fidelity (>= 16bit)
Total Harmonic Distortion + Noise (THD+N)
 Important

for audio applications (< 1% THD+N)
Signal to Noise Ratio (SNR)
 Equal
or better than digital source (>= 100dB)
DAC Architecture
Voltage-output thermometer
DAC
Requires 2n identical resistors
Current-output thermometer
DAC
Binary-weighted DAC
Requires 2n unique current
sources
R-2R DAC
Challenge:
Requires 2n-1 identical
resistors
Requires precise resistors to get LSB resolution
R-2R DAC
Current-output
Voltage-output
Output voltage
swing limited by
op-amp
Output buffer required
to provide low output
resistance
Output voltage limited to
1/3 Vref
Project Schedule

Week #1 (2/5 – 2/11)
 Finalize

Week #2 (2/12 – 2/18)
 Finalize

design goals and specifications
and test inverter and buffer
Week #3 (2/19 – 2/25)
 Finalize
gates)
and test digital components (latches,
Project Schedule

Week #4 (2/26 – 3/4)
 Begin

operational amplifier design
Week #5 (3/5 – 3/11)
 Finalize

design for operational amplifier
Week #6 (3/12 – 3/18)
 Finalize
resistor design
 Project Progress Report
Project Schedule

Week #7 (3/19 – 3/25)
 Finalize

and test voltage reference circuitry
Week #8 (3/26 – 4/1)
 Complete

Week #9 (4/2 – 4/8)
 Complete

final circuit design and layout
circuit layout and testing
Week #10 (4/9 – 4/13)
 Final
Project Presentation