Search

A 0.6 μm BiCMOS interface for microelectromechanical systems (MEMS) based rotational accelerometers is presented. It is housed in an inexpensive standard SO-24 plastic package with a capacitive rotational accelerometer sensor produced using MEMS technology. This sensitive interface chip includes the analog-to-digital conversion, filtering, and interface functions. The analog-to-digital conversion is realized through a single-bit electromechanical Σ-Δ loop able to detect capacitive unbalancing as low as 50 aF (50×10-18 F). The produced bitstream is then processed by a digital chain and made available through a standard 3.3 V (5 V tolerant) three-wire serial bus. The signal bandwidth is about 800 Hz, the sensitivity is 2.5 rad/s2, with a full-scale sinewave of 200 rad/s2 and a signal-to-noise ratio peak of 38 dB over 30-800 Hz. Through the serial bus, it is also possible to program device characteristics including gain, offset, filter performance, and phase delay. The complete sensor is used in a feed-forward compensation scheme to cancel external disturbances acting on computer hard-disk drives so as to steadily keep the read-write heads on track: this allows greater track densities and better speed performance. [ABSTRACT FROM PUBLISHER]

A dual-axis linear accelerometer, composed of a dual-axis acceleration sensor using a single proof mass to detect x- and y-axis acceleration and the relative fully integrated electronics front-end realized in a standard 0.5-µm CMOS technology, is proposed. The overall device features a full scale of ±1 g and a sensitivity of 200 µg. No external components are required since an internal switched-capacitor low-pass filter limits the output signal band to 30 Hz. The dual-axis sensor is packaged with the electronics. In the final device, only four pins are active, plus a test pin. The device sensitivity is on-chip factory trimmed. This sensitivity is adjusted with a total accuracy of ±2.5%. The device is able to detect a minimum signal of 200 µg (which is about 80 dB lower than its full scale) and consumes 45 mW from a single 5-V supply. [ABSTRACT FROM AUTHOR]

Presents a 2.5-rad/s² resolution micro-electro-mechanical system-based rotational accelerometer targeted for hard disk drive application. System considerations; Ways of implementing a force-feedback loop; Structure of the digital section.