Audio DACMatt Smith

Alfred Wanga

CSE598A/EE597G

Analog-Digital Mixed-Signal CMOS Chip Design

Spring 2006

Digital audio has become widespread in home/consumer electronics

Portable Music Players(CD, SACD, MP3)

PC Audio(Sony/Philips Digital Interface Format)

Home Theater Systems(DVD, Optical Interconnects)

Digital Audio

Design Philosophy - Goals

High Quality Audio ApplicationsAccurate ReproductionLow Noise

VersatileSupport for Standard Sampling RatesSpecifications that allow use in Various Audio

Applications

Figures of Merit

Sampling Rate Support common sampling speeds (96kHz)

Bit Depth Finer 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)

Voltage-output thermometer DAC

Current-output thermometer DAC

Binary-weighted DAC

R-2R DAC

Requires 2n identical resistors

Requires 2n-1 identical resistors

Requires 2n unique current sources

Challenge:

Requires precise resistors to get LSB resolution

DAC Architecture

Current-output

Voltage-output

Output buffer required to provide low output resistance

Output voltage swing limited by op-amp

Output voltage limited to 1/3 Vref

R-2R DAC

Project Schedule

Week #1 (2/5 – 2/11)Finalize design goals and specifications

Week #2 (2/12 – 2/18)Finalize and test inverter and buffer

Week #3 (2/19 – 2/25)Finalize and test digital components (latches,

gates)

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 designProject Progress Report

Project Schedule

Week #7 (3/19 – 3/25)Finalize and test voltage reference circuitry

Week #8 (3/26 – 4/1)Complete final circuit design and layout

Week #9 (4/2 – 4/8)Complete circuit layout and testing

Week #10 (4/9 – 4/13)Final Project Presentation