12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit...

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12-bit Digital-Analog Converter ECE262 Analog Circuit Design Team Member Team Member Team Member Team Member Chao Chen Chao Chen Chao Chen Chao Chen Jae Jae Jae Jae Shik Shik Shik Shik Lim Lim Lim Lim Lingzhao Lingzhao Lingzhao Lingzhao Xie Xie Xie Xie

Transcript of 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit...

Page 1: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

12-bit Digital-Analog Converter

ECE262 Analog Circuit Design

Team MemberTeam MemberTeam MemberTeam Member

Chao ChenChao ChenChao ChenChao ChenJae Jae Jae Jae ShikShikShikShik LimLimLimLim LingzhaoLingzhaoLingzhaoLingzhao XieXieXieXie

Page 2: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Agenda

Abstract

Background

Block Diagram

Module Level Design

System Level Design

Design Review

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Page 3: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Abstract

Design of a 12-bit Digital-Analog Converter with mixed-signal design

The lower 8 bits of digital-analog conversion are implemented by R-2R Ladder while the upper 4 bits are implemented by Binary-to-Thermometer Decoder

Carefully design the Op-Amp to optimize the performance of the DAC

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Page 4: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

BackgroundBinary-to-Thermometer Decoder

R-2R ladder requires significantly high precision

resistors and is usually limited to a max of 8-bit

resolution.

The implementation of Thermometer Decoderallows for a 12-bit resolution while only needing

the accuracy of a 8-bit DAC

N inputs thermometer decoder has 2n−1 outputs.

Each output corresponds to a base 10 value of the

possible binary inputs.

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Page 5: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Background Example of 3bits Binary-to-Thermometer Decoder

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Three bits input and corresponding seven outputs

Page 6: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Background R-2R Ladder with Thermometer Decoder

R Array

R-2R Ladder

4 bits

Thermometer

Decoder

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Page 7: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

OpampAnalogoutputAnalog

Low Pass Filter

Thermometer

Decoder

4-bit

+R-2R

Ladder

15-bit

LSB

MSB

R Array

8-bit

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Block Diagram

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Module Design

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Page 9: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

R-2R Ladder and R Array Module

Opamp

Low Pass Filter

Thermometer

Decoder

R-2R Ladder

R Array

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Page 10: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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R-2R Ladder (8bits)

Schematic

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R-2R Ladder (8bits)

Simulation using Hspice (Inputs)

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R-2R Ladder (8bits)

Simulation using Hspice (Output)

Page 13: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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R-2R Ladder and R Array Module

Layout (Both LVS and DRC clean)

Page 14: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

4bits Thermometer Decoder Module

Opamp

Low Pass Filter

Thermometer

Decoder

R-2R Ladder

R Array

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Page 15: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

15 bits output to R Array 15

4bits Thermometer Decoder Module Schematic

Page 16: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

R Array

R-2R Ladder

Thermometer

Decoder

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4bits Thermometer Decoder Module Schematic

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4bits Thermometer Decoder Module Simulation using Eldo (12bits input)

Inputs for the thermometer decoder and R-2R array

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4bits Thermometer Decoder Module Simulation using Eldo (output)

Output of the thermometer decoder and R-2R array

Page 19: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

3.29422

3.29290

Resolution=1.3mV

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4bits Thermometer Decoder Module Simulation using Eldo (magnified output)

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4 input NAND 3 input NAND4 input NOR 3 input NOR

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4bits Thermometer Decoder Module Layout for MOS Gates

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2 input NAND 2 input NOR

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4bits Thermometer Decoder Module

Layout for MOS Gates

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4bits Thermometer Decoder Module

Layout (Both DRC and LVS Clean)

Page 23: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

OP Amplifier Module

Opamp

Low Pass Filter

Thermometer

Decoder

R-2R Ladder

R Array

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OP Amplifier Module

Schematic

Page 25: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Linear through the whole range Input range: 0.575V ~ 4.807V DC Gain: 72.775 dB Phase Margin: 81.865 degrees Unity Gain Bandwidth: 28 MHz Slew rate: 8.4V/us

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OP Amplifier Module

Specification

Page 26: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

R, R-2R

Output

OPAMP

Output

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OP Amplifier Module

Simulation using Eldo

Page 27: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

1.3mV

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OP Amplifier Module

Simulation using Eldo

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OP Amplifier Module

Layout (Both DRC and LVS Clean)

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OP Amplifier Module

Layout (General View)

Page 30: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Tail bias Out bias30

OP Amplifier Module

Layout (Details)

Page 31: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

P Load P Out

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OP Amplifier Module

Layout (Details)

Page 32: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Common

Centroid

Differential

Pair

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OP Amplifier Module

Layout (Details)

Page 33: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Low Pass Filter Module

Opamp

Low Pass Filter

Thermometer

Decoder

R-2R Ladder

R Array

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Active Low Pass Filter

Schematic

Second-order unity-gain Tschebyscheff LPF

Page 35: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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Active Low Pass Filter

Simulation - Hspice

Cut off frequency: 27.24MHz

Page 36: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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Active Low Pass Filter

Simulation - Hspice

Roll-off of 2nd order LPF: 39.6712 dB/decade

Page 37: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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Active Low Pass Filter

Layout OPAmp

5k Ω

2ea

22pF

0.3pF

Page 38: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

System Design

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Page 39: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

12-bit Digital-Analog Converter Top Level Schematic

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Thermometer

Decoder +

R Array

Dummy

R and C

Source Follower

ActiveFilter

Analog

VDD

Analog

GND

Page 40: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

R, R-2R

Output

OPAMP

Output

LPF

Output

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12-bit Digital-Analog Converter Top level simulation using Eldo

Page 41: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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12-bit Digital-Analog Converter Layout (Both DRC and LVS Clean)

Page 42: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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12-bit Digital-Analog Converter All module layout

Thermometer

Decoder

(Digital)

R Array

(Analog)

OP Amp &

LPF

(Analog)

Page 43: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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12-bit Digital-Analog Converter Layout – Guard Rings

Digital Logic

Analog Circuit

P+

(GND)

N well, N+

(GND)

P+

(A Gnd)

N well, N+

(A Vdd)

Page 44: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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12-bit Digital-Analog Converter Simulation using Eldo (Max. at 14MHz)

Stable state exist, operate well at 14MHz

OPAMP

Output

R, R-2R

Output

Page 45: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Input bits: 12-bit

Input voltage: 5V

Output range: 0.58V ~ 4.80V

Resolution: 1.3mV

Bandwidth: 14MHz

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Design ReviewSpecification

Page 46: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

R and R-2R Array9 resistors with resistance 2R (=2*20 kΩ)22 resistors with resistance R (=20 kΩ)

Thermometer Decoder2 Input NAND: 8 ea 3 Input NAND: 3 ea 4 Input NAND: 1 ea2 Input NOR: 8 ea 3 Input NOR: 3 ea 4 Input NOR: 1 eaInverter: 15 ea

OP-AMPNmos: 5, Pmos: 4, C: 5pF*1

2nd order Low Pass Filter

OP-AMP Capacitor: 0.3 pF, 22pF Resistor: 5 kΩ * 2

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Design ReviewComponent used

Page 47: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

Total power consumption (from Eldo)

P_system=1.5647mW

Total Area: 1.4453 mm2

1077um * 1342 um = 1.4453 mm2

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Design ReviewPower consumption & Area used

Page 48: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

In order to improve the non linearity of analog output, we have calibrated the resistor values connected to output of the thermometer decoder

The waveform on the next slide shows that the output of resistor array has almost linear output

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Design ReviewOutput calibration

Page 49: 12-bit Digital-Analog Converterjmorizio/ee299/projects_2010/12bitDAC.pdf · Design of a 12-bit Digital-Analog Converter with mixed-signal design The lower 8 bits of digital-analog

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Design ReviewOutput calibration – simulation (Eldo)