A 0.35 μm VCO uses current switching to increase voltage swing, lower phase noise by cyclostationary noise alignment, and improve startup reliability. A CMOS VCO in a 3-metal, 0.35 μm process has -139 dBc/Hz phase noise at 3 MHz offset from a 1.8 GHz carrier and 30% of continuous tuning using inductors with Q of 6 and 4 mA dc current

Aparicio, Roberto

Hajimiri, Ali

English

Caltech Authors - Main

ISSCC 2002 / SESSION 17 /ADVANCED RF TECHNIQUES / 17.2 
17.2 A CMOS Differential Noise-Shifting Colpitts VCO 
Roberto Aparicio, Ali Hajimiri 
California Institute of Technology, Pasadena, CA 
A 0.35pm VCO uses current switching to increase voltage swing, lower phase noise by cyclostationary noise alignment, 
and improve start-up reliability. A CMOS VCO in a 3-meta1, 0 . 3 5 ~ m  process has -139dBc/Hz phase noise at 3MHz offset 
from a 1.8GHz carrier and 30% of continuous tuning using inductors with Q of 6 and 4mA dc current. 
R. Aparicio See Digest page 288 
Out1 
.__I--. . ... . --...I ____-. _-__.__^ _ll_ l _._...____- 
1 Differential Cross-Coupled VCO ne I ‘dd 
I, 
11 
/j 
3 Noise in Oscillators 
Cross-Cou pled Osci I lator 
Noise Shifting Colpitts Oscillator 
Experimental Results 
Ij 
1 
I‘ 
/I B i d  ( 
0.8 
0.4 
0.0 
-0.4 
0 ~112 TI 3~112 2n 
Conclusions 
r ii , .Limited Cyclostationary Noise Alignment Improvement 
Oscillator Noise 
m Phase Noise i 2  lw r 2  
To Lower Phase Noise Tei/(wt) 4 y,”,, fi 
A. Hajimiri and T. Lee, “A General Theory of Phase Noise in 
Electrical Oscillators’’, JSSC Feb. 98 
I . . .. ______ -. .I__- I^. . .^I.-.-. ... . . 
Single Ended Colpitts VCO 
‘dd 
I .L 
0.6 
0.0 
-0.6 
0 ~112 TI 3n12 2n 1 
.Significant Cyclostationary Noise Alignment Improvement 
1 ~ -  I ___I- _ _ ~ - - -  __  - _______l_ll 7- - -- 
jj Effective ISF Impulse Sensitivity Function (ISF) I .*+. ... NMOS 
[I 0 8 .-*;#’-?-.. _. comr 
- Effective ISF 
ref(@ = I-(@.a(a) 
.The Noise Modulating Function 
(NMF) describes the noise 
amplitude modulation I . ’ .  . 
0 TI2 T 3Tl2 2T 
T=l I f o  
Oscillator Eff ISF Amplitude Start Up Gain Output 
NMOSor Larger-Non 2 
/I PMOS Symmetric ~ ~ t a n k l b r a s  Low Differential 
Comple- Larger-Non 4 
mentary symmetric FRfank’bms 
!i 
226 ISSCC 2002 VISUALS SUPPLEMENT / 0 IEEE 
-----I-- -- 
Differentia I Evolution 
-r "dd 'dd 
Bias -I 
'bias 
O TI4 TI2 3Tl4 T 
T= 1 Ifo 
.The Drain Current is Almost Zero for Half of the Cycle 
A Proposed Topology 
I L  
-Maximize Vswlng 
-Loop gain > 3 
-c, = 4c, 
Bias = 
-* - ------*-- .- p - - - a m =  
7 
[I] D Ham and A Hajimiri, Concepts and Methods In Optimization of 
Integrated VCOs: JSSC June 2001 
[2] A Hajimiri and T Lee, 'A General Theory of Phase Noise in Nactr~cal 
Oscillators': JSSC Feb 98 
Cyclostationary Noise Sources 
'dd T 
Bias Bias 
1.4 
0.7 
0.0 
-0.7 
0 n12 TI 3~112 2 n  
$- Bias = *The Noise Generation is Maximum when 
the Oscillator is the Least Sensitive 
Implemented VCO 
I supply 1 2.5V I Voltage 
I I 
Frequency Tuning 
2.4 - 
I g 2.2 
s 2.0 
x 
c 
u- 
LL 
s? 
1.8 
Control Voltage [VI pG&q-7q 
30.5% 420MHzN 
-- _I _-I__- I_-_ _ _ _ _  -- - _  _I 
Phase Noise 
-139 dBc1Hz @ 3MH2, fo=  1.8GHz 
-80 
-90 
-1 00 
-110 
-120 
-130 
-1 40 
104 105 106 107 
Offset Frequency [Hz] 
Inductor Quality Factor (a) = 6 
Iblas= 4mA V, = 2 5V 
-- -_ I__- . --_1 - I -_j___--- --.__I I __ 
Continued on 
II__ __  
Page 
. . 
I____ 
484 
0 IEEE / ISSCC 2002 VISUALS SUPPLEMENT 227 
ISSCC 2002 / PAPER 17.1 ISSCC 2002 / PAPER 17.2 
Tiebout 
de Muer, et al. 
Continued from page 225 Continued from page 227 
__c_I____ -_I_ - - -=-I__=- - 
JSSC, July 2001 
JSSC, July 2000 
Summary of Measured Characteristics 
Zannoth, et al. 
1.7 GHz 
ISSCC 1998 -173.3 
107 MHz tuning l l  
4.5 mA core bias I 
I -1 52 d6clHz @ 3MHz 
QTANK = 16.5 I 
___.__ ___- -----_i - -- % r I 
Comparison to Recent Integrated VCOs 
This Work I ISSCC 2002 I -196.5 I 
Hegazi, Sjoland, Abidi I ISSCC 2001 I -192.9 I 
-181.1 
Ham, Hajimiri I JSSC, June 2001 I -178.8 I 
Leeson's 1966 FOM 
C & LC Filtering 
*LC network designed to 
resonate at 2f0 
*The inductor and capacitor can 
be bypassed by a laser trim 
Phase Noise @ 3MHz, fO=l .8GHz 
LC filter -1 38.2dBclHz 
A novel noise-shifting Diferential Colpitts VCO is 
presented. 
Uses current-switching to increase the voltage 
swing, lower phase noise by cyclostationary 
noise alignment, and improve the start-up. 
A CMOS VCO is fabricated in a 3-meta1, 0.35pm 
process with a phase noise of -1 39dBc/Hz @ 
3MHz, from a 1.8GHz carrier and 30% of 
continuous tuning'using inductors with Q of 6 
and 4mA of dc current. 
484 ISSCC 2002 VISUALS SUPPLEMENT IO 


A CMOS differential noise-shifting Colpitts VCO

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