17.4 16MHz FRAM Micro-Controller with a Low-Cost Sub-1μA Embedded Piezo-Electric Strain Sensor for ULP Motion Detection

Ultra-low Power Microcontrollers (MCUs) [1]-[4] have played a central role in embedded IoT systems providing programmability, analog and digital processing and control, A/D interfaces, and power management. As IoT applications expand, efficient sensing is increasingly becoming part of MCUs. In this paper we present a 130nm 16MHz Ferro-electric RAM (FRAM) based MCU with a sub-1uA embedded piezo-electric strain sensor and AFE for ULP motion detection (Fig. 17.4.1). To our knowledge, this is the first reported MCU with an embedded motion detection strain sensor. Existing applications that would benefit from such a MCU are applications like toys and remote controls that can turn off while not in use. Motion detection in a key fob improves security by preventing a "man in the middle" attack while the key fob lies stationary at home. Tamper detection and strain gauges are other potential applications. When used in "wake-on-motion" applications, the sensor IP is powered-on at all times waiting for a motion event. Hence minimizing its power consumption is crucial. Also, considering ULP MCUs have many cost-sensitive applications, the sensor must be small in area, and not require any additional masks or special processing steps. A single-chip solution allows reuse of power management, programmability and control circuits already existing in the MCU for use in the strain sensor IP, reducing the system level cost vs a 2-chip solution.