Tamara I. Ahrens & Thomas H. LeeCenter for Integrated Systems

Department of Electrical EngineeringStanford University

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University 1 of 28

A 1.4-GHz 3-mW 0.5-µmCMOS LC Low Phase Noise

VCO Using Tapped Bond WireInductorsAugust 10, 1998

2 of 28

A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Outline

• Goals

• Approach

• Circuit

• Results

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Goals of Design

• GPS - 1.575 GHz, IF=200MHz

• Low Power

• Minimum Phase Noise

• Tunable

• Reasonable Area

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

200 MHz IF Frequency for GPS

IF Amp

1.4 GHz

1.6 GHz

0.2 GHz 200MHz

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Ring Oscillator vs. LC Oscillator

Ring Oscillator: Dissipates all stored energyeach cycle

High power dissipation

Large tuning range

LC Oscillator: Dissipates 1/Q of the energyin the resonant tank

Lower power dissipation

Q =Stored energy

Dissipated energy* 2π

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Frequenc y Instabilit y - Time Domain

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Frequenc y Instabilit y - Freq Domain

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Units of Phase Noise

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

1/f noise of CMOS vs BJT

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

How To Achieve Low Phase Noise

• More Power

• Higher Q Resonant Tank(use of bond wires and tapping)

• Single-ended Symmetry (Hajimiri and Lee, “A general theory of phase

noise in electrical oscillators,” IEEE J. Solid-StateCircuits, vol. 33, no. 2, Feb. 1998.)

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Basic LC Oscillator Configuration

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

LC Tank

Oscillator Block Diagram

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Why Single-sided Symmetry

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Basic Desi gn Confi guration

LC Tank

Wp = 2 x Wn

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Implementing the LC Tank

A B

C D

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Implementing the LC Tank

-R -R

a b

- V +- V +

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Implementing the LC Tank

a b

- R - R

cdie

package

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Circuit Diagram

Vcontrol

L1

L2

bond wires

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Die Photo and Packaging

diepackage

Bond Wire Inductor

1mm

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Output Spectrum of Oscillator

Frequency (100 kHz/div)Center at 1.4 GHz

Mag

nitu

de (

10 d

B/d

iv)

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Phase Noise vs. Offset Frequency

Pha

se N

oise

(dB

c/H

z)

-107dBc/Hz @ 100kHz

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Frequency vs. Control Voltage

0.0 1.0 2.0 3.0Control Voltage (V)

1.1

1.2

1.3

Fre

quen

cy (

GH

z)

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Results

Frequency 1.4 GHz

Power 3 mW at 3.0V supply

Phase Noise -83 dBc/Hz @ 10kHzfor various offsets -107 dBc/Hz @ 100kHz

-122 dBc/Hz @ 600kHz

Tuning Range 220 MHz (17%)

Process Technology 0.5-µm standard CMOS

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Figure of Merit- CMOS w/Bond Wires

Figure of Merit(dBF) = 20 log(freq) - PN - 10 log(power)

Tapping [3] 1.8 GHz 24 mW -109 dBc/Hz 310 dBF

FrequencyPhase Noise (PN)

Method Power FOM@100kHz

This work 1.4 GHz 3 mW -107 dBc/Hz 315 dBF

Single-sided 1.6 GHz 0.5 mW -95 dBc/Hz 312 dBFSymmetry [2]

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Figure of Merit- Various Technologies

CMOS [6] 1.8 GHz 6 mW -105 dBc/Hz 312 dBF

Freq

Phase Noise (PN)

Technology Power FOM@100kHz

This work 1.4 GHz 3 mW -107 dBc/Hz 315 dBF

BJT [4] 1.1 GHz 2 mW -95 dBc/Hz 302 dBF

BiCMOS [5] 1.8 GHz 70 mW -88 dBc/Hz 285 dBF

Figure of Merit(dBF) = 20 log(freq) - PN - 10 log(power)

BJT oscillator

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Figure of Merit- Ring vs. LC

Ring Oscillator 1.8 GHz 10 mW -75 dBc/Hz 280 dBF

Freq

Phase Noise (PN)

Design Power FOM@100kHz

This work 1.4 GHz 3 mW -107 dBc/Hz 315 dBF

Figure of Merit(dBF) = 20 log(freq) - PN - 10 log(power)

Ring Oscillator 1.2 GHz 20 mW -80 dBc/Hz 278 dBF

Ring Oscillator 5.4 GHz 80 mW -79 dBc/Hz 284 dBF

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Conclusions

• Tapping allows a greater amount of energy inthe resonant tank, thereby increasing thesignal energy without increasing the noise.

• Independently, single-sided symmetryreduces the up-converted low frequency phasenoise contribution from the active devices.

• CMOS is a growing and attractive solution forRF oscillators.

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A 1.4-GHz 3-mW CMOS LC Low Phase Noise VCO using Tapped Bond Wires

Tamara I. Ahrens Center for Integrated Systems Department of Electrical Engineering Stanford University

Acknowledgements

For their various contributions, the authors would like to thank:

• Ali Hajimiri

• David M. Colleran

• Sunderarajan Mohan

• Robert W. Dutton

• Maria Perea

• Michael A. Swartwout

• Leah K. Meagher