Ultra-Low-Power Circuits for Wearables

Transcription

1 Ultra-Low-Power Circuits for Wearables Philippe Bourban

2 Outline ON Semiconductor quick facts Power budget of some wearable devices Things to think about to make ULP circuits A few circuit examples 2 11/30/2016

3 ON Semiconductor Today Headquarters: Phoenix, AZ Employees: ~30,000 globally Revenue: ~$5Bn (1) Market Capitalization: ~$4.9Bn (2) Ticker: ON Founded: Spun-off from Motorola 1999, IPO 2000 (1) Estimated Fiscal 2017 Revenue per Factset 11/8/2016; (2) As of October 24, 2016; Sector % based on 3Q16 3

4 Proven Leadership Growth Drivers Industrial ASIC #1 PC Core Power (DCDC) #1 Notebook Adapters (ACDC) #1 White Goods IPM #2 Adaptive Front Lighting #1 Automotive Image Sensors #1 Security Image Sensors #1 Audiology DSP Systems #1 Protection #1 GP Op Amps #2 Linear VREG #1 Automotive Power Conversion & Motor Control Image Sensors Wireless Devices Industrial IoT Sources: isuppli, IMS Research, Strategy Analytics, Fuji Chimera Research, ON Semiconductor Business Units and Corporate Marketing 4

5 Typical elements in wearable devices Power management unit Sensor(s) Data acquisition chain(s) Data processing Driver Actuator / Display Accelerometer Gyroscope Magnetometer Altimeter Barometric pressure Heart rate ECG Oximetry Respiration Infrared Skin conductance Skin temperature Ambient temperature Ambient light UV Signal conditioning (amplify, filter ) A/D conversion μc DSP ASIP Dedicated HW Wireless connectivity NFC RFID Bluetooth Classic Bluetooth Low-Energy ANT Wifi 5 11/30/2016

6 Power budget of some wearables (1) AR glasses Sportswatch Fitness tracker Fitness tracker Recon Instruments Snow2 HUD Samsung Gear S2 Tomtom Spark Cardio+Music Garmin Vivosmart HR V V V V 6 hours 36 hours (display on) 72 hours (display off) 740 mw 26 mw (display on) 13 mw (display off) Wifi, BT, GPS 9-axis accel. & gyroscope Compass sensor Pressure sensor Temperature sensor 0.2 TFT-AMLCD display Wifi, BLE, NFC 6-axis accel. & gyroscope Heart Rate sensor Pressure sensor Ambient light sensor 1.2 Super Amoled display 5 /11 hours (music/gps) 3 weeks (activity tracking) 175/80 mw (music/gps) 1.7 mw (activity tracking) GPS, BT 6-axis accel & gyroscope Heart Rate monitor Bio-sensor 3-axis magnetometer 1.3 LCD display 8 hours (use) 120 hours (standby) 38 mw (use) 2.5 mw (standby) GPS, BLE, ANT 3-axis accelerometer Heart Rate sensor Pressure sensor 1.6 TFT-LCD display 1 GHz dual-core OMAP4430 Graphics processor 1 GHz dual-core Exynos 3250 ARM Cortex M7 Atmel 8-bit MCU 120 MHz ARM Cortex M4 Data from /30/2016

7 Power budget of some wearables (2) Bluetooth earbuds Bluetooth earbuds Bluetooth earbuds Hearing Aid Bragi Dash Earin Motorola moto hint 89765N V V V V (disposable) 4 hours 3 hours 10 hours 100 hours 92 mw 74 mw 44 mw 2 mw BT audio streaming 3-axis accelerometer Gyropscope Magnetometer Dual pulse oxymeter sensor BT audio streaming BT audio streaming Audio processing Audio streaming 7 11/30/2016

8 A few power consumption numbers Circuit BLE radio GPS Wifi ARM Cortex M3 Exynos bit 1 Msps 3-axis digital accelerometer Power consumption 10 mw (peak) 70 mw 240 mw 0.1 mw/mhz 0.25 mw/mhz (14nm FinFET) 0.2 mw 3 mw (peak) 1 to 30 uw 1 Hz) 8 11/30/2016

9 Typical Power Saving How to make ULP circuits? High System Software / algorithm Architecture Main power contributors? HW/SW partitioning Power-down Complexity Concurrency Regularity Processor architecture Analog vs digital Parallelism/Pipelining/Encoding Low Circuit Analog: Weak inversion Transistor sizing Digital: Voltage reduction Activity reduction Power gating State retention Technology Flavors (LP, etc ) Multi-threshold devices FDSOI / DDC / back-biasing 9 11/30/2016

10 Understand the power breakdown Audio streaming Analog Consumer monitoring Analog Medical implantable Analog Radio Digital Radio Digital Radio Digital Radio active 7.6% of the time Receive 48 kbps, 10 ms frames Dynamic power dominant (audio decompression) Avg power: 1.5 mw Sleep 96% of the time Wake up every 100 ms to send 20 bytes Dynamic power is dominant Avg power: 50 mw Sleep 99.9% of the time Wake up every 10 s to send 20 bytes Memory leakage power is dominant Avg power: 1.5 mw 10 11/30/2016

11 Select the right processor architecture Dedicated Hardware Energy Efficiency ASIP DSP Flexibility General Purpose Processor 11 11/30/2016

12 Reduce the supply voltage: yes but P dyn = a* f * C * V dd^2 P stat = I off * V dd Trade-off power versus performance (operating frequency) Process variability at low voltage V t mismatch FD-SOI, DDC 12 11/30/2016

13 Which process technology? Performance Analog (noise) Computing Cost Development Production Power Static Dynamic System partitioning Technology selection RF technology Die area Memory needs Flash availability Today s popular choices for a wearable SoC Low-cost : 180 nm Mainstream : 65 nm / 55 nm Advanced : 40 nm / 28 nm 13 11/30/2016

14 ULP circuit examples 14 11/30/2016

15 Efficient DC-DC converter Efficiency [%] LTC3549 (high efficiency buck converter) ON Semiconductor Buck efficiency vs load V out = 1.5V 100% 90% 80% Buck efficiency vs load V out =1.2V 70% 60% 1 ma load 50% 40% 30% Vin=3.3V Vin=1.8V 20% 10% 100 ma load 0% 1.E-06 1.E-04 1.E-02 1.E+00 1.E+02 Load Current [ma] High efficiency step-down conversion at low load currents (100 na to 100 ma) is important for ULP circuits or for use cases where the system is often idle (e.g. vital signs sensing) 15 11/30/2016

16 ADC energy efficiency LTC2440 (Linear) ISL26102 (Intersil) WM8786 (Wolfson) AD1974 (AD) PCM4220 (TI) MAX98091 (Maxim) TLV320 (TI) State-of-the-art in /30/2016

17 ADC energy efficiency LTC2440 (Linear) ISL26102 (Intersil) WM8786 (Wolfson) AD1974 (AD) PCM4220 (TI) MAX98091 (Maxim) TLV320 (TI) State-of-the-art in 2013 ON 2007 (audio) ON 2014 (audio) ON 2010 (ECG) ON 2002 (monitoring) 17 11/30/2016

18 Trends in wearables More sensors More wireless, with multi-standard radios Lower power consumption of individual functions Smaller technology nodes (40nm & 28 nm) SoC integration (AFE + mc + radio) Security 18 11/30/2016

19 Conclusion ULP circuits are at the heart of wearables Low-power is in the DNA of local companies due to the watch industry heritage Neuchâtel and Western Switzerland are well equipped to solve most low-power challenges in wearables devices 19 11/30/2016

20 Questions? 20 11/30/2016