SiTime Corporation · NASDAQ:SITM
SiTime — Technical Presentation (February 2013)
15 slides from SiTime's technical presentation, Feb 25, 2013
Slide 1: Silicon Oscillator Frequency Characteristics and Measurements
SiTime University Turbo Seminar Series Silicon Oscillator Frequency Characteristics and Measurements February 25, 2013
Slide 2: Agenda
Agenda • Oscillator frequency stability: MEMS vs. Quartz • Common questions on frequency stability specs • How to make accurate frequency measurement for oscillators 2
Slide 3: Frequency Stability
Frequency Stability • Frequency Stability f f f nom • Defined as relative variation of frequency from nominal Fsta • Expressed in part per millions (PPM) f f nom • Example: ±100 PPM of 100 MHz clock means frequency of clock can be • Lower frequency: 100 MHz – 100 PPM = 99.99 MHz • Upper frequ
Slide 4: Stability vs. Temperature: SiTime MEMS vs. Quartz Oscillators
Frequency Stability vs. Temperature: SiTime MEMS vs. Quartz Oscillators Frequency stability over Temperature Frequency Stability over Temperature 25 25 20 20 15 15 10 10 Frequency (ppm) Frequency (ppm) 5 5 0 0 ‐5 ‐5 ‐10 ‐10 ‐15 ‐15 ‐20 ‐20 ‐25 ‐25 ‐40 ‐20 0 20 40 60 80 ‐40 ‐20 0 20 40 60 80 Temperat
Slide 5: Stability vs. Temperature: SiT8208/9, SiT9120/1/2, SiT1602 Series
Frequency Stability vs. Temperature: SiT8208/9, SiT9120/1/2, SiT1602 Series SiT8208 SiT9121 25 25 Frequency (ppm) Frequency (ppm) 15 15 5 5 ‐5 ‐5 ‐15 ‐15 ‐25 ‐25 ‐40 ‐20 0 20 40 60 80 ‐40 ‐20 0 20 40 60 80 Temperature (°C) Temperature (°C) SiT1602 25 Frequency (ppm) 15 5 ‐5 ‐15 ‐25 ‐40 ‐20 0 20 40 6
Slide 6: Stability vs. Temperature: SiT5000 ±2.5ppm TCXO
Frequency Stability vs. Temperature: SiT5000 ±2.5ppm TCXO SiT5000 2.5 Frequency (ppm) 0 ‐2.5 ‐40 ‐20 0 20 40 60 80 Temperature (°C) 6
Slide 7: Stability vs. Supply Voltage: SiTime MEMS vs. Quartz Oscillators
Frequency Stability vs. Supply Voltage: SiTime MEMS vs. Quartz Oscillators Quartz Oscillators from 3 vendors SiT1602 / SiT8008 PPM Voltage Dependence of Crystal Oscillators PPM Voltage Dependence of SiT1602/SiT8008 4.096MHz 27MHz 54MHz 4.096 MHz 27 MHz 54 MHz 6 6 4 4 2 Different vendors 2 PPM Change
Slide 8: Common Questions on Frequency Stability
Common Questions on Frequency Stability • Do SiTime MEMS oscillators frequency vs. temperature characteristics depend on output frequency? No Frequency VDD Oscillator CMOS Die programmed by Voltage fraction-N PLL. PLL MEMS Charge Regulators is locked to Pump “Sustaining Circuit” Resonator Bias CLKou
Slide 9: Common Questions on Frequency Stability
Common Questions on Frequency Stability • Can SiTime MEMS oscillators achieve aging specs better than Quartz? YES 9
Slide 10: Frequency Counter Principle
Frequency Measurement Frequency Counter Principle Average frequency measurement • Modern frequency counter use time interval measurement over a number of clock cycles to measure frequency • Time internal measurement as accurate as 20ps pk-pk • Resolution independent of clock frequency 10
Slide 11: Measurement Accuracy
Frequency Measurement Accuracy Time base stability Time interval error • OCXO: 0.1ppm to 1ppm • 20 ps to a few ns (pk-to-pk) • High-end OCXO: 0.01 to 0.1 ppm • < 200 ps for modern counters • Rubidium: 1 part-per-billion (ppb) • Resolution independent of input clock frequency • GPS-disciplined: 0.01
Slide 12: Sources of Measurement Error
Sources of Measurement Error Poor Connection to Frequency Counter Trigger Error • Noise or waveform distortion on input clock signal causing frequency measurement error • Affected by probe setup and/or impedance mismatch Frequency OSC Out Counter GND Improper signal connection to counter causing err
Slide 13: Proper Connection to Frequency Counter
Proper Connection to Frequency Counter Loading Effect on Oscillator • Counters have 50 ohm or Hi-Z inputs • Driving 50 ohms load can increase oscillator IDD significantly • Increased IDD means more power dissipation and higher die temperature • Driving high-impedance counter inputs can cause signifi
Slide 14: How to Make Accurate Frequency Counter Measurement?
How to Make Accurate Frequency Counter Measurement? • Choose proper Gate Time (>100 ms) • Use good internal time-base option (<0.1ppm OCXO), or • Use external frequency reference for accurate and repeatable measurements across instruments (GPS-disciplined sources) • Use probe setup that minimizes lo
Slide 15: Contact Information
Contact Information • For Questions, contact SiTime Technical Support Technicalsupport@sitime.com • Turbo Webinar pdf downloads on SiTime’s web site • Webinar recordings are posted on SiTime’s web site www.sitime.com/support/sitime-u/turbo-webinars • All new webinars are posted within 24 hours 15