a silicon die as a frequency source - university of...

©2009 Integrated Device Technology, Inc.

A Silicon Die as a Frequency Source

IEEE International Frequency Control Symposium Noise & Measurement Techniques Lecture Session A3L-B Newport Beach, CA June 2, 2010

Michael S. McCorquodale, Ph.D. General Manager Silicon Frequency Control Integrated Device Technology 111 W. Evelyn Ave. Suite 210 Sunnyvale, CA 94086 (408) 329-5021 [email protected]

1

of 34 www.IDT.com IEEE IFCS Newport Beach, CA USA June 2010

Overview

 Mobius Microsystems and IDT  Comments on quartz replacement  A silicon die as a frequency source  Applications  Conclusions

Quartz Replacement Silicon Die Freq. Source Applications Conclusions Mobius and IDT


MOBIUS MICROSYSTEMS AND IDT

Mobius and IDT Quartz Replacement Silicon Die Freq. Source Applications Conclusions


Mobius Microsystems

  Mobius was founded in 2004 out of the U. of Michigan by M. McCorquodale and R. Brown

  Core technology is an all-silicon (CMOS) frequency reference that meets the performance requirements of several applications served by XTALs and XOs

  Initial product model was IP and initial IP product has shipped over 10Mu

  Mobius transitioned to a component product model in 2006

  Initial components were launched in 2008 with modest success

Mobius and IDT Quartz Replacement Silicon Die Freq. Source Applications Conclusions


Mobius Microsystems and IDT

  Mobius revised its products and embodiments in stealth mode

  New components perform significantly better (e.g. total operating power is ~2mA, down from 12mA)

  IDT acquired Mobius on Jan. 14, 2010

  Silicon Frequency Control (SFC) is a new business unit at IDT focused on quartz replacement with silicon devices

  The SFC/IDT silicon die component was announced on Apr. 29, 2010

  This talk is about this new silicon frequency reference Mobius and IDT Quartz Replacement Silicon Die Freq. Source Applications Conclusions


COMMENTS ON QUARTZ REPLACEMENT

Quartz Replacement Mobius and IDT Silicon Die Freq. Source Applications Conclusions


Quartz Components


Simple, 2, or 4-pin

Crystal Resonator Broad-based SMD < 40MHz <20c

Crystal Oscillator Broad-based SMD 1–150MHz ~45c to >$2.00

Crystal + PLL IC Broad-based SMD 1MHz–>1GHz > 50c >$2.00 (total)

2-pin Passive XTAL Resonator

Broad-based DIP <40MHz <10c


MEMS-Based Silicon Frequency Sources


High-Q MHz MEMS resonator Assembled device

Sealed resonator

2-die stack: Resonator + CMOS

High-Q MHz MEMS resonator Assembled device

2-die stack: Sealed

resonator

3-die stack: Resonator + CMOS


CMOS-Based Silicon Frequency Sources


Single-chip, self-referenced CMOS frequency source (0.13µm)

Single-chip, self-referenced CMOS frequency source (0.13µm)


FBAR-Referenced Frequency Sources


1.5GHz FBAR frequency source

Shailesh Rai, et al., “A Digitally Compensated 1.5 GHz CMOS/FBAR Frequency Reference” IEEE Trans. on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 57, no. 3, March 2010


A Comparison to Quartz


MEMS

IDT/Mobius

XO

  All packages are DFN 5mmx3.2mm

  What is the difference between these devices?

  It has been shown that the performance of both MEMS and CMOS oscillators is inferior to quartz

  Why choose one device over the other?

  Why choose anything but quartz?


What we have seen in the market

  What is the value proposition of these new devices? −  Performance is inferior to quartz

−  These new devices are often lumped together with passives at very low ASP

  Proposed value includes: size, lead-time and inventory −  In the end these are all cost – that is the only value

proposition

−  In the market we see that performance is a threshold and cost is the driver

−  The real question: does it meet spec. and is it cheaper?



A SILICON DIE AS A FREQUENCY SOURCE

Silicon Die Freq. Source Quartz Replacement Mobius and IDT Applications Conclusions


All-Silicon Frequency Sources

  Free-run a CMOS RF LC oscillator at >GHz

  Design high-resolution process trimming

  Design open-loop temperature compensation

  Actively regulate the power supply

  Frequency divide by a large factor

  Develop a low jitter and stable reference spanning fundamental to overtone XTAL frequencies





  Due to the parasitic RL & RC present in a integrated implementation:

  RL(T) & RC(T) cause a temperature-induced frequency drift:

  Temperature drift is negative, concave down and dominated by RL

RL

L C

RC




A myriad of 1st, 2nd and 3rd order variables affect error


Simplified Reference Oscillator (1st Gen.)

TR[12:0]

Cf [12:0]

TR[12:0]

Cf [12:0]

TC[5:0] TC[5:0]

vctrl(T) VDD

Cv [5:0]

TC[5:0]

vctrl(T) VDD

Cv [5:0]

TC[5:0]

VDD

vbias

VDD

Fixed thin film caps trim nominal

frequency Cv (vctrl(T )) compensates LCO over T

High-swing pMOS cascode bias



Simplified Reference Oscillator (2nd Gen.)

TR[X:0]

Cf [X:0]

TR[X:0]

Cf [X:0]

VDD VDD

TC in coil is corrected by a

lossy capacitance


TC[Y:0]

Cf [Y:0]

TC[Y:0]

Cf [Y:0]

RC[Y:0] RC[Y:0]

  Primary source of TC

  If a lossy capacitance, RC , can be introduced to cancel RL , the TC will be flat

  Enables very low power (~2mA)

€

ω1(T) =ωoCRL (T)

2 − LCRC (T)

2 − L

€

ω1(T) =ωoCR(T)2 − LCR(T)2 − L

=ωo


Fringing Fields


Package molding compound fills voids between interconnect

Last metal in conformal

process

Epoxy molding compound

  The fringing E-field off of the device acts as a parasitic capacitor

  The molding compound shifts the frequency due to the fringing E-field (new εr); it also has a TC

  The B-field also fringes out of die and can be modulated by eddy currents induced in any metal over or under the device


Si=200µm

Faraday Shield


Fringing B-field from coil Bond pad

Parasitic capacitance from fringing

E-field

Backside metallization

Topside metallization with dielectric

stand-off

Very thin Si die thickness can be

supported


Faraday Shield


  The process sequence is critical to avoid wafer warping   Die are trimmed with a parallel wafer-scale test platform   The tested/trimmed silicon die can be packaged in any manner


Performance


  TC is below ±100ppm in production test over 0-70C

  Curvature arises from nonlinearity in the TC

  The distribution arises from the process variation and the trimming algorithm


Performance


  TC is only one component of total frequency stability

  Additional tests include bias sensitivity, wander, HTOL, HAST, 3x solder reflow, and thermal hysteresis

  Each line item captures an offset and standard deviation

  The final error (±300ppm) is determined from by totaling statistics for these line items


Performance


Integrated jitter is close to meeting optical

carrier requirements

12kHz to 5M


APPLICATIONS

Applications Quartz Replacement Silicon Die Freq. Source Mobius and IDT Conclusions


Applications and Market Sizes

  USB: USB flash drive and card reader (UFD/UFCR), etc.   Serial ATA (S-ATA): HDD, SSD   PCIe: Storage   SIM card



Quartz Components

Simple, 2, or 4-pin

Crystal Resonator Broad-based SMD < 40MHz <20c

Crystal Oscillator Broad-based SMD 1–150MHz ~45c to >$2.00

Crystal + PLL IC Broad-based SMD 1MHz–>1GHz > 50c >$2.00 (total)

2-pin Passive XTAL Resonator

Broad-based DIP <40MHz <10c



A Silicon Die Frequency Source in an MCP


Assembled MCP

Silicon die frequency

source

Application processor

Dissolved package

  The die freq. source assembled in a multi-chip package (MCP)   Here the die “looks” like IP to the end user


CoB in USB Drive in Package (UDP)


USB controller

Silicon die frequency

source Memory


CoB in USB Drive in Package (UDP)


  The die freq. source assembled with a chip-on-board (CoB) process   Note that the Faraday shield was dissolved with the package


USB Link Performance


CMOS

XO

Referenced to CMOS oscillator

Referenced to XO


CONCLUSIONS

Conclusions Quartz Replacement Silicon Die Freq. Source Applications Mobius and IDT


Conclusions

  A new silicon die frequency source was introduced where the production qualified performance is ±300ppm over all conditions

  A Faraday shield post-process was introduced which enables the device to be tested at wafer and assembled in any package post-test just like a passive device

  It was shown that this silicon die frequency source uniquely positioned for quartz replacement in several high-volume applications



THANK YOU QUESTIONS WELCOME


a silicon die as a frequency source - university of...

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