Summary

Complex ΔΣ DA modulator

Study of Complex Multi-Bandpass#DWA algorithm for I-Q Signal Generation

P75

M. Murakami, S. Mohyar, H. Kobayashi, T. Matsuura, O. Kobayashi†, M. Tsuji†, S. Umeda†,R. Shiota†, N. Dobashi†, M. Watanabe†, I. Shimizu, K. Niitsu‡, N. Takai, T. J. Yamaguchi"

Dept. of Electrical Engineering, Graduate School of Engineering, Gunma University†STARC, ‡Nagoya University

Complex multi-bandpass DWA

DWA algorithm

*Data Weighted Averaging｜Select the element with DSP algorithm

Introduction

‣ Multi-bit DAC

◎ Relaxes the analog filter requirements

× Degrades system linearity

◎ DWA algorithm

Low cost, high quality I,Q signal generation.

‣ Complex multi-BP ΔΣ DAC

‣ I,Q signal generation with digital centric for testing communication IC.

!"#$%&%'()'(

!"#$%&'*#"+)#,,-./$(01

2/&/(#$ !"#$%&

2!3

2!3

2/&/(#$/")'(

!!!"#"#

!!!#"#"

!"#$%&'(*#"+)#,,-4%+'$#(%1 DWA

δI

δQ

Simulation result ~Actual Non-Linear DAC ＋ DWA~

-140

-120

-100

-80

-60

-40

-20

0

-0. 5 -0. 4 -0. 3 -0. 2 -0. 1 0 0. 1 0. 2 0. 3 0. 4 0. 5

Po

we

r [d

B]

in / s

w/o DWA

-140

-120

-100

-80

-60

-40

-20

0

-0. 5 -0. 4 -0. 3 -0. 2 -0. 1 0 0. 1 0. 2 0. 3 0. 4 0. 5

Po

we

r [d

B]

in / s

w/ Complex DWA

DWA

Steep NotchesNotches filled with noise

DWA

0

10

20

30

40

50

60

1 2 3 4 5 6

SN

DR

[d

B]

OSR (2n)

w/o Complex DWA

Complex DWA

w/

Complex Multi-Bandpass DWA algorithm

DAC2（HP operation）DAC１（LP operation）

DAC

Inpu

tD

AC

Inp

ut

TIME

Iin

4

3

2

2

6

1

7

5

Qin I0 I1 I2 I3 I4 I5 I6 I7

2

2

6

1

7

5

4

3

Iin

4

3

2

2

6

1

7

5

Qin I0 I1 I2 I3 I4 I5 I6 I7

2

2

6

1

7

5

4

3

N = 4（four zero points）

DWA ＝ ΔΣNon-Linearity

z -1DAC Output

z -1Input

δ

Can’t be realized directly

Integration Differentiation

δ affected by only Differentiation

DACPointer

InputOutput

Equivalent circuit for implementationMemorize!next cell selection start point

δ

!"#$%&'()

*%+,

#-..$$/(01-2%3 %4 %5 %6 %7 %8 %9 %:

7

6

5

9

8

4

:

!"#$%&'()*

Memorize!next cell selection start point

S1

S2

S3S4

S5

S6

S7S0

VDD

VDD

VDD

VDD

VDD VDD

VDDVDD

I + e0

I + e1

I + e2

I + e3I + e4

I + e5

I + e6

I + e7

Vout

R

DWA DAC

Multi-bit DAC ＋ DWA*

S1 S2 S7S0

I + e0 I + e1 I + e2 I + e7

R

VDD

Vout

Multi-bit DAC

!"#$%&'()

*%+,

#-..$$/(01-2%3 %4 %5 %6 %7 %8 %9 %:

7

6

5

9

8

4

:

Accumulate mismatch of particular cell

Normal unary DAC!"#

ei : current source mismatch

Multi-bit DA modulator

Multi-bit DA modulator（2~3bit）

Quantization noise reduction Linearity degradation

Relax

Down

1bit

Multi-bit

Error

Digital

Analog

2nd-order complex multi-BP ΔΣ DAC

EI

EQ

a b

d

d c

c

b

Iin

Qin

Iout

Qout

H(z)

a

DACI

DACQ

H(z)

Out

put

sp

ectr

um

N = 1 N = 4

Single-band Multi-band

EI

EQ

a b

d

d c

c

b

Iin

Qin

Iout

Qout

H(z)

a

DACI

DACQ

H(z)

EI

EQ

a b

d

d c

c

b

Iin

Qin

Iout

Qout

H(z)

a

DACI

DACQ

H(z)

DAC

DAC

-140

-120

-100

-80

-60

-40

-20

0

-0. 5 -0. 4 -0. 3 -0. 2 -0. 1 0 0. 1 0. 2 0. 3 0. 4 0. 5

Po

we

r [d

B]

in / s

-140

-120

-100

-80

-60

-40

-20

0

-0. 5 -0. 4 -0. 3 -0. 2 -0. 1 0 0. 1 0. 2 0. 3 0. 4 0. 5

Po

we

r [d

B]

in / s

Principle of complex BP noise shape

QoutQin

IoutIinEI

EQ

H(z)

DAC

DAC

Complexresonator

+1

1 + H(z)(EI + jEQ)

Iout + jQout =H(z)

1 + H(z)(Iin + jQin)

Power

ω

H(z)Quantization noises

Signal Transfer Function = 1

Noise Transfer Function = 0

Research Objective

Multi-bit DA modulator（2~3bit）

Linearity degradation

Low quality signal

DWA algorithm

High quality signal

Research Objective

Low cost, high quality signal

High quality testing

ΔΣ Complex

＋Bandpass

Filter

Analogoutput

Digitalinput

...0101DACDSP

testingsignal

Research Background

Co

st

（C

en

ts /

Tra

nsis

tor）

テストコストの傾向（ITRS 2001）

コスト

（Cents / Transistor）

年

Silicon

Testing

1

10-3

10-6

1990 1995 2000 2005 2010 2015

Year

Demand for communication IC testing

Silicon cost

Testing cost

Lower

Higher

：：