GYROSCOPE IMU MEMS ASIC
Ever noticed the Segway personal mobility device, that’s illustrated here? This mobility system appears to perform an impossible task. It can support an adult on a platform suspended between two parallel wheels and is capable of accelerating to 15km/h. It manages to maintain balance and offers a highly intuitive speed and direction control system. All the magic here is performed by a tri-axis MEMS gyroscope (IMU) based control system.
ICsense conceived and designed the gyroscope interface system which comprises a high voltage MEMS driver circuit and precision angular rate detection circuits. To ensure the MEMS sensor operates in its resonant mode, the driver system can be tuned with a 12-bit precision and is capable of achieving sub-Hertz tuning accuracy – ultimately leading to the highly stable control system for which this transporter is known.
ICsense’s expertise in gyroscope MEMS
- Low noise switched capacitor gain stages
- Precision band pass filters
- Quadrature compensator
- 12-bit precision, micro power analog to digital conversion
ACCELEROMETER MEMS ASIC
For a consumer tri-axis accelerometer digitization ASIC project in 0.18 micron CMOS, a complete design study was carried out to model a fully integrated signal path solution for the MEMS readout system. The project lead to the design of a state-of-the-art sensor architecture
ICsense’s expertise in accelerometer MEMS
- Micro power operation below 100µA
- Sensor nominal capacitance 400fF with 10fF/g dynamic variation (±2g to ±16g programmable)
- 1% accuracy over consumer temperature range
- On-chip parasitic capacitance compensation (up to 1.2pF)
MAGNETIC MEMS ASIC
A distinct strength of ICsense is integrating sensor interfaces and actuation circuitry for MEMS IMU sensors. An excellent example of this is a precision fully integrated magnetic Hall sensor ASIC we developed. From project start, we contributed to the development of the Hall sense elements, enabling the trade-off of key parameters including area, structure and sensitivity. To reduce inherent offset, we implemented a layout of four Hall plates with 90° current direction exploiting current spinning (i.e. Spin Hall effect). The sensor signal chain consists of low-offset, low-noise amplifiers followed by precision voltage to current conversion. The ADC is a 15-bit extended counting delta-sigma design with an equivalent per LSB current of 1.4nA – equating to a 0.4 micro Tesla minimum system resolution.
ICsense’s expertise in magnetic MEMS
- Quad Hall sensor integration with 90° (quadrature) current direction
- Exploits the Spin Hall Effect (SHE)
- Low-offset, low-noise instrumentation signal path
- 15-bit extended counting delta sigma ADC
- System sensitivity of 0.4µT/LSB
- Offset < 6mTRMS noise of less than 0.5µT (rms) with a current of a few 100µA
- 0.18µm CMOS process
- Industrial temperature range -40 to 85ºC