11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 1 of 54

Meisam Heidarpour Roshan1,2,Samira Zaliasl1, Kimo Joo1, Kamran Souri1, Rajkumar Palwai1, Will Chen1,

Sudhakar Pamarti3, Joseph Doll1, Nicholas Miller1, Carl Arft1, Sassan Tabatabaei1, Carl Sechen2, Aaron Partridge1, Vinod Menon1

1SiTime, Sunnyvale, CA2University of Texas at Dallas, Richardson, TX

3University of California, Los Angeles, Los Angeles, CA

Dual-MEMS-Resonator Temperature-to-Digital

Converter with 40µK Resolution and FOM of 0.12pJK2

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 2 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Precision Oscillator Applications

±0.5ppm ±0.01ppm - ±1ppm±1ppm - ±10ppm

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 3 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Precision Oscillator Resonators

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 4 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

MEMS-Based Programmable Oscillator Package

MEMS die, CMOS die and leadframe in a package

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 5 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

MEMS-Based Programmable Oscillator (XO)

Output stability matches reference resonator

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 6 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

MEMS-Based Programmable Oscillator (TCXO)

Temperature-to-Digital Converter (TDC) is needed

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 7 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Specifications

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 8 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Specifications

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 9 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

State-of-the-Art TDCs

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 10 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Prior Architectures UnsuitablePerrott

[ISSCC 2012]

Resolution FOM = (Energy/Conversion)×Resolution2

K.A.A. Makinwa, "Smart Temperature Sensor Survey", [Online]. Available: http://ei.ewi.tudelft.nl/docs/TSensor_survey.xls

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 11 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• Different temperature coefficients (TC) for two clockso Frequency ratio indicates temperatureo TempSense clock (ClkTS): TC = -7ppm/Ko TempFlat clock(ClkTF): TC < 1ppm/K

Dual-MEMS Resonator TDC

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 12 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• Reciprocal counting method• Counts OSC1’s number of cycles in a time window

set by OSC2 and counter2

Frequency Ratio Measurement Techniques

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 13 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Proposed Ratio Engine

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 14 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Proposed Ratio Engine

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 15 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Proposed Ratio Engine

VCO is locked to ClkTF

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 16 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Proposed Ratio Engine

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 17 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 18 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 19 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 20 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 21 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 22 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Implementation Flow

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 23 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 24 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 25 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 26 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 27 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Digital PFD

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 28 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Digital PFD

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 29 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 30 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 31 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 32 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

More Details

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 33 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Chip Micrograph

FrequencySynthesizer

DigitalDriver

• 0.18µm CMOS• 0.54mm2

o Resonator included• 12mA current for:

o Sustaining circuitso Frequency ratio engineo Digital

• Supply voltage: 1.6V

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 34 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Resolution Measurement Setup

Thermal insulator is needed

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 35 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Resolution Measurement Setup

Environmental noise dominates the TDC resolution

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 36 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Resolution Measurement Setup

Instead of TDC output, clock PN is measured

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 37 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Contribution on PN

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 38 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Contribution on PN

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 39 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Contribution on PN

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 40 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Contribution on PN

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 41 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TDC Contribution on PN

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 42 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TCXO with Gained-up TDC

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 43 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

TCXO with Gained-up TDC

TDC has 40µK resolution over a BW of 130Hz

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 44 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

MEMS Resonators’ Stability Measurements

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 45 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Measured TCXO’s Stability

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 46 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Measured TCXO’s Stability

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 47 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Allan Deviation Measurement

TCXO meets the ADEV target of < 1e-10

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 48 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Comparison Table

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 49 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Energy/Conversion vs. Resolution*

Resolution FOM = (Energy/Conversion)×Resolution2

*K.A.A. Makinwa, "Smart Temperature Sensor Survey", [Online]. Available: http://ei.ewi.tudelft.nl/docs/TSensor_survey.xls

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 50 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

Energy/Conversion vs. Resolution*

Resolution FOM = (Energy/Conversion)×Resolution2

*K.A.A. Makinwa, "Smart Temperature Sensor Survey", [Online]. Available: http://ei.ewi.tudelft.nl/docs/TSensor_survey.xls

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 51 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• The first of a new category of the temperature sensors

Conclusions

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 52 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• The first of a new category of the temperature sensors

• Dual-MEMS-Resonator TDC:o Resolution of 40µK Æ 2.5x improvemento Resolution FOM of 0.12pJK2 Æ 5.5x improvement

Conclusions

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 53 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• The first of a new category of the temperature sensors

• Dual-MEMS-Resonator TDC:o Resolution of 40µK Æ 2.5x improvemento Resolution FOM of 0.12pJK2 Æ 5.5x improvement

• MEMS-Based Oscillator for telecom applications:o Allan Deviation of < 1e-10 in 1s averaging timeo Frequency stability of < ±0.1ppmo Temperature range of -40°C to 85°C

Conclusions

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference 54 of 54

11.1: Dual-MEMS-Resonator Temperature-to-Digital Converter with 40µK Resolution and FOM of 0.12pJK2© 2016 IEEE International Solid-State Circuits Conference

• Prof. Kofi Makinwa for his support, review, and comments!

• Nazariy Tshchynskyy, Anton Prygrodskyi and Trushal Chokshi from SiTime for their dedicated support during the measurements

Acknowledgement