A digital interface for gyroscopes controlling the primary and secondary mode using bandpass sigma–delta modulation
✍ Scribed by T. Northemann; M. Maurer; S. Rombach; A. Buhmann; Y. Manoli
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 580 KB
- Volume
- 162
- Category
- Article
- ISSN
- 0924-4247
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✦ Synopsis
This paper demonstrates a micro-electro-mechanical gyroscope system with extensive use of sigma-delta ( ) modulation in both, primary and secondary modes. Both control schemes are implemented digitally on a field programmable gate array (FPGA). The primary loop has a bandpass digital-to-analog converter (DAC) driving the primary mass into resonance using a two-level driver. With this strategy of replacing the discrete DAC of the primary oscillation control with a bandpass -DAC, the analog circuit complexity is enormously reduced. The Coriolis rate signal is converted into a bit stream with a new excess loop delay (ELD) compensated micro-electro-mechanical modulator ( M) incorporating the gyroscope in the loop with a second-order electrical bandpass filter (BPF). To investigate the ELD effect, this electro-mechanical M is implemented on the FPGA emulating continuous-time (CT) behavior. Measurements show stable modulators, with an ELD of nearly one clock period of the sampled system, achieving in-band noise (IBN) below -60 dBFS. The full-scale (FS) is measured to 1019 • /s. This paper demonstrates that the stability of modulators with large ELD can be ensured with the new ELD compensation technique.