PCIRF_6_9_VCO

7/29/2019 PCIRF_6_9_VCO

http://slidepdf.com/reader/full/pcirf69vco 1/57

A. Tasic © 20091

On the Phase Noise

and Noise Facto r in

Circu its and Sys tems - New Though ts on an Old

Subject Aleksandar Tasic

QCT - Analog/RF Group

Qualcomm Incorporated, San Diego

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 2009 2

Outline

• Spectral Analysis of Noise in LC-Oscillators

• LC-tank, g m-cell, bias current source noise

• (Phase-) Noise factor

• Bipolar vs. CMOS LC-Oscillators

• LC-Oscillators Noise Reduction Methods

• Mixer Noise Factor from VCO Noise Factor

• Oscillator Phase Noise in Receiver’s SNR

• LNA and Mixer Noise Factors in a Receiver

• BBFilter Noise Transfer vs. LO/Mix Duty

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20093

Phase Noise Model o f B ipo lar and

CMOS

LC-Osci l lators

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20094

Outline

• Oscillation Condition

• LC-Tank Noise Folding

• gm

-Cell Noise Folding

• Bias-Current Source Noise Folding

• Phase-Noise Model of Bipolar LC-Oscillators

• Phase-Noise Model of CMOS LC-Oscillators• Bipolar vs. CMOS LC-Oscillators

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20095

LC-Oscillator Noise Sources

LC-tank noise

transconductor noise

bias current source noise

L/ 2

Q1 Q

2

QCS

~ ~

v B1 v B2

iC 1 iC 2

i B2

i B1

iGTK

i BCS

2C

I TAIL

RTK / 2 RTK / 2

L/ 2

2C

2 ( ) 2 / 2 N C C mi I qI KTg

2 ( ) 2 N TK TK i G KTG

2( ) 2 N B Bv r KTr

2

, , ,( ) (1 2 ) N BCS m CS B CS m CS i I KTg r g

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20096

Oscillator and Phase-Noise Model

• phase-modulating noise component (double-sided)

*0 , 0 , 01( ) ( ) ( )2

PM N O N Oi f i f i f

*0 , 0 , 0

1( ) ( ) ( )

2 PM N O N Oi f i f i f

• phase-related noise power (single-sided)2

2 2 ,2

, 0 0 0 2

1

( ) ( ) ( )2 4

PM TOT

PM TOT PM PM TOT

i

v i f i f Z f C

i AM

iS

i PM

*, 0( ) N Oi f

, 0( ) N Oi f ‘

‘

LC-tank

g m-cell

+ N v

, NOv

, NOi

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20097

g m -Cell Transfer Function

• Fourier domain – (magnitude) complex harmonic components

2 f 0 f 0-f 0 f 0-2

g 0 g 2 g -2

f 0-4

g -4 g 4

4 f 03 f 0-3 f 0

2

2

sin( )i

i d g gd

i d

00

0

/42

2/4

0

2( )

T j i t

iT

g g t e dt T

1

2

d

k

• small-signal gain in the presence of a large signal

1 / f 0 1 / 2 f 0

- g = g m / 2 d / 2 f 0

t

i OUT

v S

= d i d v S g IN OUT

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20098

Oscillation Condition• harmonics: g m-cell and oscillation signal

• convolution:

• oscillation signal:

• oscillation condition:

g 0

2 f 0 f 0-f 0 f 0-2

g 2 g -2

vS / 2 vS / 2

g 0

2 f 0 f 0-f 0 f 0-2

g -2

g 0 g 2vS / 2 vS / 2

vS / 2 vS / 2

0 0 0 00 0 2 2 0 2

( ) ( ) ( ) ( )( )

2 2 2 2

S S S S S TK S TK

v f v f v f v f v g g g g R g g v R

0 2 TK g g G

small-signal loop gain:

k =R TK g m/2

duty cycle:

d=1/(2k )

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 20099

0

( ) N

v f

2 f 0 f 0-f 0 f 0-2

g 0

0

( ) N

v f 0( ) N v f 0( ) N v f

g 2 g -2

0( ) N v f

2 f 0 f 0-f 0 f 0-2

g 0 0( ) N v f 0( ) N v f

0( ) N v f g 0 g 0 g 0

LC-Tank Noise Folding• convolution: g 0 and g 2 harmonics and LC-tank noise

0( ) N v f

2 f 0 f 0-f 0 f 0-2

g 0

0( ) N v f 0( ) N v f

0( ) N v f

g 2 g -2

0( ) N v f

2 f 0 f 0-f 0 f 0-2

0( ) N v f 0( ) N v f 0( ) N v f g -2 g 2 g 2 g -2

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200910

• LC-tank noise contribution:

LC-Tank Noise Folding

, 0 0 0 2 0( ) ( ) ( ) N O N N i f g v f g v f

, 0 0 0 2 0( ) ( ) ( ) N O N N i f g v f g v f

, 0 0 0 2 0( ) ( ) ( ) N O N N i f g v f g v f

, 0 0 0 2 0( ) ( ) ( ) N O N N i f g v f g v f

0( )

N v f

2 f 0 f 0-f 0 f 0-2

g 0 0( )

N v f

0( ) N v f 0

( ) N

v f g 0 g 0 g 0

0( ) N v f

2 f 0 f 0-f 0 f 0-2

0( ) N v f 0( )

N v f

0( ) N v f g -2 g 2 g 2 g -2

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200911

LC-Tank Noise Contribution• phase-modulating noise component:

• LC-tank noise transfer function:

2 2 2 220 22( ) ( ) 2 ( )2 ( ) 4

( ) 14 4 4 4

N N PM TK TK TK TK TK TK

TK TK TK TK

g g v R G v Ri R KTG F R

KTG KTG KTG KTG

• LC-tank noise factor:

, 0 , 0 , 0 , 0

1( ) ( ) ( ) ( )2

PM N O N O N O N Oi i f i f i f i f

0 2 0 0 2 0( ) ( ) ( ) ( ) PM N N i g g v f g g v f

• phase-related noise power (k >>1, g =g 0=g 2):

2 2 20 2( ) ( )TK TK g R g g G

2 2 2

0 2( ) ( ) ( ) PM N TK TK i R g g v R

C

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200912

0

( ) N

v f

2 f 0 f 0-f 0 f 0-2

g 0

0

( ) N

v f 0( 3 ) N v f 0( 3 ) N v f

g 2 g -2

0( )

N v f

2 f 0 f 0-f 0 f 0-2

g 0 0( )

N v f

0( )

N v f

0( )

N v f g 0 g 0 g 0

0( ) N v f

2 f 0 f 0-f 0 f 0-2

0( ) N v f 0( ) N v f 0( ) N v f g -2 g 2 g 2 g -2

f 0-4

g -4

0(3 ) N v f 0(3 ) N v f

g 4

0( ) N v f 0( ) N v f

4 f 03 f 0-3 f 0

g m -Cell Noise Folding• convolution: g 0 and g 2 harmonics and f 0 g m-cell noise

• g m-cell noise around odd multiples of the oscillation frequency is

folded to the LC-tank noise around the oscillation frequency

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200913

g m -Cell Noise Contributions

2 22 (2 ) 2 4(2 ) 2

4 4

PM B TK B B B TK

TK TK

i r kG KTr F r kr G kc

KTG KTG

• g m-cell noise factors:

• phase-related noise power:22 2 2 2 2 22

2 2 21 2( ) ( ) ( ) ( ) 2 ( )

2 PM N N N

im IN i i m IN m IN m IN

g i g g g v g v g dg v g d d

• g m-cell noise transfer function:

2 2 2 2 21( ) 2 2 ( ) 2 ( )

2 2

m

m IN TK TK

g g g dg d kG kG

k

2 22 (2 ) 2 2 / 1(2 ) /

24 4

PM C TK mC TK m

TK TK

i I kG KT g F I kG g

KTG KTG

Bi C t S N i

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200914

Bias Current-Source Noise

Transfer Function• g m-cell large-signal V -to-I transfer function

I

V IN

1 /f 0

OUT

1 / f

1

-1

I OUT

0

• Fourier domain – (magnitude) complex harmonic components

2 f 0 f 0-f 0 f 0-2

c1c-1

f 0-4

c-3 c3

4 f 03 f 0-3 f 0

2 1

sin((2 1) / 2)

(2 1) / 2i

ic

i

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200915

• BCS noise factor:

• phase-related noise power:

• BCS noise transfer function:

22 ( ) (1 2 ) 2 (1 2 )

( )4 4 4

1 1(1 2 ) ( ) (2 ) (2 )

2 2

PM BCS m B m TK BCS

TK TK TK

C B

i I KTg r g KT kG kc F I

KTG KTG KTG

k kc k kc k F I F r

BCS Noise Contribution

2,2 2( ) 1

( ) ( )4 4

PM DIFF BCS PM BCS N BCS

i I i I i I

2 1( )

4 BCS g I

BCS noise around even multiples of the oscillation frequency is

folded to the LC-tank noise around the oscillation frequency

Ph N i M d l f

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200916

Phase-Noise Model of

Bipolar Switching LC-Oscillators

• Noise factor:( ) (2 ) (2 ) ( )

1 2 1 1 21 ( ) 1 (1 ) ( )

2 3 2 2 3

TK C B BCS F F R F I F r F I

F kc k kc k kc k

2 2 2

( ) (2 ) (2 ) ( ) 4

(4 ) (4 )S

TK C B BCS TK

TOT TOT

R I r I KTG F

C v C

L L L L L

• Phase noise:

2

2 2

1 21 (1 ) ( )

4 2 3( )8(4 )

TK

T TOT

k kc k KTG

V C k L

8S T v kV

Ph N i M d l f

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200917

• Constant phase-noise contributions

• LC-tank noise contribution ~ 1

• g m-cell current shot noise contribution ~ ½

• Small-signal loop-gain related contributions

• g m-cell base-resistance noise contribution ~ 0.66ck

• phase-noise contribution of the bias current source is

k -times larger then the noise contribution of the g m-cell ~

k (½+ck )!

Phase Noise Model of

Bipolar Switching LC-Oscillators

1 2 11 ( )2 3 2

F kc k kc

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200918

• high ss loop-gain, high quality LC-tank, BCS noise present:

2

1 1( )

3 1 12 2~ ~

5 10

k kc kc

k k k

L

e.g., k >>1(=10), c <<1(~0.01)

2

7 3(1 )

56 2~ ~1

4

k

k

L

e.g., k~1(=2), c ~1(~0.5)

Low/High-Performance VCO Designs

• low ss loop-gain, low quality LC-tank, BCS noise present:

• high ss loop-gain, high quality LC-tank, BCS noise eliminated:

e.g., k >>1(=10), c <<1(~0.01)

2 2

1 21

7.8 1 1 12 3~ ~5 1010

kc

k k L

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200919

Single/Double-Switch CMOS LC-VCO

2

,( ) 2 N BCS m CS i I KT g

2( ) 2 N D mi I KT g

2 ( ) 2 N TK TK i G KTG

TK N

m

Gd

g

Q1 Q2

Q3 Q4

Q2

QCS

i D1 i D2

i BCS

Q1

i D1 i D2

i BCS QCS

i D3 i D4

L/ 2

iGTK

2C

RTK / 2 RTK / 2

L/ 2

2C

V DD

L/ 2

iGTK

2C

RTK / 2 RTK / 2

L/ 2

2C

2

TK C

m

Gd

g

2

, ,( ) 2 N D P P m P i I KT g

2

, ,( ) 2 N D N N m N i I KT g

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200920


CMOS LC-Oscillators

,

( ) (2 ) ( )

1 /(4 )

SS TK D BCS

SS m CS TK

F F R F I F I

F g G

2 2 2

( ) (2 ) ( ) 4

(4 ) (4 )S

TK D BCS TK

TOT TOT

R I I KTG F

C v C

L L L L

• Phase noise:

,

22

1 /(4 )4

2(4 ) ( )

m CS TK TK SS

TAIL TK

g G KTG

C I R

L

• Noise factor ( N = P , g m,N =g m,P ):

,

( ) (4 ) ( )

1 /

DS TK D BCS

DS m CS TK

F F R F I F I

F g G

,

22

1 /4

4(4 )( )

m CS TK TK DS

TAIL TK

g G KTG

C I R

L

f

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200921


CMOS LC-Oscillators

• Constant phase-noise contributions

• LC-tank noise contribution ~ 1

• g m-cell drain-current thermal noise contribution ~

• Small-signal loop-gain related contributions (?)

• bias current source noise contribution ~ g m,CS /GTK (k )

,1 /m CS TK F g G

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200922

CMOS vs. Bipolar LC-Oscillators

1 21

2 3 BIP F kc

1CMOS F

• noise factors (for removed BCS noise):

• bipolar VCO better for the same power consumption (v s,BIP =v s,CMOS )

3 2 5

2 3 3kc

8

TK B

Rkr

• e.g., k =10, R TK =800

80010

80 Br

• e.g., k =10, R TK =80

801

80 Br

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200923

CMOS vs. Bipolar LC-Oscillators

• power consumption figure of merit:

• V CC =1.8V, v s,BIP =0.4V, v s,SS-CMOS =1.2V, (3I CC,BIP =I CC,SS-CMOS)

2

0

10log ( ) CC CC FOM V I L

4.8 BIP SS CMOS FOM FOM dB

• V CC =1.8V, v s,BIP =0.4V, v s,DS-CMOS =1.2V, (1.5I CC,BIP =I CC,DS-CMOS)

7.8 BIP DS CMOS FOM FOM dB

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200924

Phase-Noise Model Conclusions

Parametric Phase-Noise Model electrical circuit parameters (ss loop gain)

worst-case phase noise (bandwidth unlimited)

Bipolar vs. CMOS LC-Oscillators bipolar ss loop-gain related contributions

v S,BIP~k (<<V CC ), v S,CMOS~V CC

bipolar capacitive tapping for larger v S,BIP, butalso larger k -related noise contributions and

power consumption

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200925

Suppress ion o f B ias Curren t-Source No ise

in

LC-Osci l lators

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 2009

Outline

• Contribution of Bias Current-Source Noiseto Phase Noise of LC-Oscillators

• Techniques for Reduction of Bias Current-

Source Noise• Noise Analysis of Degenerated Bias

Current Source

• Bias Noise Suppression - Design Example

26

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200927

VCO Noise Contributions

LC-tanknoise ~ 1

transconductor

noise ~ 0.5+c •k

bias current-source

noise ~ (0.5+c •k )•k

Q1 Q

2

QCS

v B1

v B2

iC 1 iC 2

i B2i B1

i BCS

C A

C B

C A

C B

I TAIL

C C

L

V V

iGTK

V CC

V TUNE

~~

VCO N i C t ib ti

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200928


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

4 6 8 9.6

r B,CS

I C,CS

r B

I C

R TK

BCS:~85%

g m :

~15%

k

• f 0~5.74GHz, R TK ~340 , n~1.65, c ~0.25, V CC =2.2V

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200929

Bias Noise Reduction Techniques

resona ntinductivedegeneratio n(RID)resistive degeneration(RD)commonemi tter(CE)

high supply

required large area if

integrated

noise injection if

discrete

transconductor

noise always ON

reduced output

impedance

resistive

degenerationinductive

degeneration filtering?

V IN

I TAIL

V IN

I TAIL

R D

LD

V IN

I TAIL

+

-

C D

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200930

Capacitive Filtering

AC short

AC open

20

1

d / 0 f 2

1/ f 0

1/ f 0

0

d’ / 0 f 2

1

1' (1 )2

d d

'(2 ) ~2

C

n F I k

1

2d

k

(2 ) ~ 2C

n F I

• for k =10, d =5%, d’ =52.5%, and F’>F

Bias Current Source with

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200931

Bias Current Source with

Resonant-Inductive Degeneration

LRID matched to C at 2f 0

r B,CS noise contribution reduced

transconductance gain small at resonance series resonance

I B,CS noise contribution small

common-base like configuration (gain of 1)

I C,CS noise contribution removed

parallel resonance

emitter open at resonance (I C,CS floats)

LRID

V IN

I TAIL

C


7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200932


after RID applied to BCS

• f 0~5.74GHz, LRID~1.3nH, R TK ~340 , n~1.65, c ~0.25, V CC =2.2V

0%

20%

40%

60%

80%

100%

4 6 8 9.6

r B,CS I C,CS

r B

I C

R TK

BCS:

~6%

g m :

~94%

k

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200933

to groundto ground

to TCS transistors to ground

VCO w/ RID vs. VCO w/o RID

Ph N i ( / RID / RID)

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200934

with RID

without RID

Phase Noise (w/ RID vs. w/o RID)

• 6dB phase-noise improvement with RID

• -112dBc/Hz @1MHz from 5.7GHz @ 4.8mA&2.2V

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200935

RID Conclusions

BCS noise >> g m-cell and LC -tank noise

Resonant inductive degeneration good suppression of high frequency BCS noise

low voltage operation

small chip area (vs. discrete solutions)

BCS DC noise upconversion

large area (vs. resistive degeneration) poorer noise suppression at high supplies (vs.

resistive degeneration)

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200936

Oscillator Conclusions


• Phase-Noise Model

• LC-tank, g m-cell, bias current sourcecontributions

• Bipolar vs. CMOS LC-Oscillators

• Oscillator Noise Reduction Methods• Resonant-Inductive Degeneration

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200937

Future Worries

• Low-(Supply and Swing)-Voltage Operation

• Linear and Quasi-Linear Phase-Noise Model

• Low-Performance Oscillators• Noise-Reduction Methods

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200938

Worri less

Low-Voltage LC-Osci l lators

L V lt Bi l LC VCO

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200939

Low-Voltage Bipolar LC-VCO

LC-tank(fixed or tunable)

transconductor and C-coupling

f 0-tuning

C C C C

R B

R B

V V

Q1 Q

2I BIAS

L

C

V CC

C

V TUNE

C C

R RD R

RD

QCS

R RD-CS

resistive

degeneration

bias

current

L V lt CMOS LC VCO

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200940

Low-Voltage CMOS LC-VCO

LC-tank

(fixed or tunable)

transconductor

f 0-tuning

resistive

degeneration

V V

Q1 Q2

L

C

V CC

C

V TUNE

C C

R RD R

RD

V I BIAS,TUNE V I BIAS,TUNE bias current

Pros of Emitter (Source) Tuned

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200941

Pros of Emitter (Source)-Tuned

LC-VCOs

Low supply voltage operation - single transistor

between rails

Stable g m-cell bias from resistive degeneration Controlled degeneration/bias current/swing

from triode MOS transistor

(Large) frequency-tuning range combined emitter/LC-tank tuning

Pros of Emitter-Tuned LC-VCOs

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200942

Pros of Emitter-Tuned LC-VCOs

Good phase noise – trade-off between

degeneration/bias current/voltage swing g m-cell noise suppressed at all times

(large) voltage swing – trade-off between

resistive degeneration and bias current lossy emitter varactor away from LC-tank

superior high-frequency (e.g. 60GHz)

performance over tail-biased VCOs

1/f noise contribution large for small transistors

in tail-biased VCOs

1/f noise contribution reduced with degeneration

in emitter-tuned VCOs at all times

7/29/2019 PCIRF_6_9_VCO


Folding of Mixer Noise Components

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200945

( ) N

v

2 f 0 f 0-f 0 f 0-2

( ) N

v

0( )

N v f

2 f 0 f 0-f 0 f 0-2

c1

0( )

N v f

0( 3 )

N v f

0( 3 )

N v f

c3

c-1

f 0-4

c-3

0(3 )

N v f

0(3 )

N v f

0( )

N v f

0( )

N v f

4 f 03 f

0-3 f

0

1

2 f 0 f 0-f 0 f 0-2

g 0 g -2 g 2

3 f 0-3 f 0

0( 2 )

N v f

0( 2 )

N v f ( )

N v( )

N v 0

(2 ) N

v f 0

(2 ) N

v f

Folding of Mixer Noise Components

RC load

switching pair

g m cell

• RC load noise components at offset frequency

• switching pair noise components around even LO

multiples

• g m-cell noise components around odd LO multiples

CMOS Mixer Noise Power

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200946

CMOS Mixer Noise Power

• g m-cell noise contribution

• switching pair noise contribution

• total output noise power

• RC-load noise contribution2 2

( ) 2 ( ) 4 N NF TOT TOT TOT v R v R KTR

2 2 2(2 ) ( ) 2 N NF D TK D TOT v I dR i I KT R

22 2( ) 2 ( ) /

4 N

TK NF m m TOT TOT

Rv g i g KTR G

2 2 (2 )2

CMOS TOT

TOT

v KTRG

Bipolar Mixer Noise Power

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200947

Bipolar Mixer Noise Power

• gm-cell noise contribution

• switching pair noise contribution

• total output noise power

• RC-load noise contribution2 2

( ) 2 ( ) 4 N NF TOT TOT TOT v R v R KTR

2 2 2(2 ) ( ) N NF C TK C TOT v I dR i I KTR

2 ( ) 2 (1 2 ) NF m TOT v g KTR k kc

2 1 22 2 (1 2 )

2 3 BIP TOT v KTR kc k kc

2 24 2(2 ) 2 2 ( 0.5 )3 3

NF B TOT TOT v r KTR dk c KTR kc d k

(CMOS) VCO vs Mixer Noise Power

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200948

(CMOS) VCO vs. Mixer Noise Power

• 2X more correlated VCO folded noise components

• x½ for correlated VCO single-side band phase-noise

related components (2X½=1X VCO vs. Mix noise

components)

• load noise contribution: VCO gain=(g 0+g 2)2R TK

2=1 vs.

Mix gain= ½(1+1)2=2

• switching pair noise contribution: VCO gain=1 vs. Mixgain=1

• tail noise contribution: VCO gain=1 vs. Mix gain=2 (½

VCO PN contribution lost in AM noise from c 0 conversion)

2, 2 (1 )

4CMOS VCO TOT

TK

v KTRG

2, 2 (2 )

2CMOS MIX TOT

TOT

v KTRG

(Bipolar) VCO vs. Mixer Design

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200949

(Bipolar) VCO vs. Mixer Design

• Constant noise-figure contributions

• RC-load noise contribution ~ 2

• switching pair current shot noise contribution ~ ½

• Small-signal gain related contributions• switching pair base-resistance and g m-cell noise

contributions ~ k 2 and d

• Mixer small-signal gain independent of LO signal

swing

• Trade-off between LO swing (~1/d ) and switching

pair small-signal gain (~k )

2 21 42 2 (1 2 )

2 3 BIP TOT v KTR dk c k kc

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200951

System Phase Noise

X

XVCO_Q

VCO_I

PN=f 2(PN VCO)

XVCO

VCO

VCO_Q

VCO_I

/n

X

X

VCO_I

VCO_Q

PN VCO

PN VCO

PN=f 1(PN VCO)

Mixer Noise Factor in a System

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200952

Mixer Noise Factor in a System

XR S

R S

R L

F MIX

F MIX

LNA

F LNA

M

R SR S X

R S

R L

F MIX

F MIX

R S

F LNA

F=f 1(F MIX )

F=f 2(F MIX )XF MIX

F MIX

R S

R S /2

900

power

combiner

LNA Noise Factor in a System

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200953

LNA Noise Factor in a System

X

X

LNAVCO_Q

VCO_I

X

XVCO_Q

VCO_I

X

X

VCO_Q

VCO_I

+

-F LNA

F MIX

F MIX

F=F LNA

F=f 1(F LNA)

F=f 2(F LNA)

F=f 3(F LNA) F=f 4(F LNA)

IR

BBF Noise in a System

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200954

BBF Noise in a System

+-

-+

+-

-+

RF+

RF-

I+

Q+

I-

Q-

R R TIA

LNA+

• BBF Noise Power Transfer vs. passive mixer impedance

degeneration and LO duty cycle

Receiver Noise (Signal)

7/29/2019 PCIRF_6_9_VCO


A. Tasic © 200955

Receiver Noise (Signal)

Transformations

• Noise Power Transfer – power matched

interface

• Noise Power Combining• Noise Voltage/Current Transfer - resonant-

matched interface

• Noise Voltage/Current Combining

• Correlated/Uncorrelated Combining (e.g.,

I-mixer gm-cell noise splits between I and Q

paths)

7/29/2019 PCIRF_6_9_VCO


Conclusions


• LC-tank, g m-cell, bias current source noisecontributions

• Bipolar and CMOS VCO Noise Factors

• LC-Oscillators Noise Reduction Methods

• Mixer Noise Factor from VCO Noise Factor

• Oscillator Phase Noise in Receiver’s SNR

• Mixer Noise Factor in a Receiver

• LNA Noise Factor in a Receiver

PCIRF_6_9_VCO

Documents

Transcript of PCIRF_6_9_VCO