Semiconductors for IoT are ultra-low-power microcontrollers and mixed-signal SoCs integrating sensors, wireless (BLE/Zigbee/LoRa), power management, and energy harvesting for battery-free or multi-year coin-cell operation.

Ultra-Low-Power Design Principles:

• Sleep current: sub-µA standby (1 µA = 70 mA/year @ 1.5V coin-cell)
• Active mode minimization: duty-cycled operation (99.9% asleep)
• Subthreshold SRAM: operate memory below threshold voltage (pV/V-scale memories)
• Near-threshold computing: CPU operation at minimal supply voltage

Microcontroller Architectures:

• ARM Cortex-M0+: single-issue, 32-bit, ultra-low-power baseline
• Instruction extensions: no floating-point, no multiplication for energy conservation
• Nordic nRF52840: integrated BLE radio + ARM M4, real-world 1-2 year battery lifetime
• TI SimpleLink: unified architecture across temperature/power/wireless variants
• Silicon Labs EFR32: energy-friendly RF, integrated power management

Sensor Hub Integration:

• Always-on sensor processor: dedicated low-power core monitors accelerometer/temperature
• Interrupt-driven wakeup: main CPU sleeps until threshold crossed
• Timestamp data: allow edge AI inference on continuous sensor streams without constant CPU wake

Energy Harvesting:

• Photovoltaic: solar cell charger, suitable for indoor/outdoor deployment
• RF harvesting: rectifier for ambient wireless signal energy
• Thermoelectric: Peltier-effect generation from thermal gradients
• PMIC (power management IC): manage multiple harvesting sources + backup battery

Wireless Protocols:

• BLE (Bluetooth Low Energy): 2.4 GHz, 10-100 m range, per-packet power ~50 µJ
• Zigbee: mesh networking, optimized for IoT home automation
• LoRa: long-range (>10 km), ultra-narrow-band, sub-mA operation

Applications:

• Smart home sensors (temperature, occupancy, light)
• Industrial monitoring (vibration, pressure, humidity)
• Wearables (activity tracking, vital signs)

IoT semiconductor success metric: years of uninterrupted operation on disposable power source—driving architectural innovation in power gating, memory design, and wireless duty-cycling.