Lianhong Zhou; Annamalai, M.; Jeongwook Koh; Minkyu Je; Libin Yao; Chun-Huat Heng, "A Crystal-Less Temperature-Independent Reconfigurable Transmitter Targeted for High-Temperature Wireless Acoustic Telemetry Applications," Circuits and Systems II: Express Briefs, IEEE Transactions on , vol.60, no.9, pp.542,546, Sept. 2013 doi: 10.1109/TCSII.2013.2273727 URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6573322&isnumber=6595586
Abstract:
A reconfigurable acoustic telemetry transmitter employing crystal-less temperature-independent frequency reference has been realized in 1m SOI CMOS process. The transmitter can be configured to transmit either 3-channel chirp signal or 6-channel OOK signal to provide flexibility based on channel characteristic. Different frequencies derived from the crystal-less temperature-independent frequency reference are directly modulated by input data before being combined and sent through a MFB low pass filter. The resulting 3-channel chirp signal achieves a total data rate of 60bps while the 6-channel OOK signal achieves a total data rate of 120bps. The frequency reference is realized through a FLL employing RC phase shifter with resistor temperature coefficient cancellation technique. It achieves a frequency inaccuracy of ±1.94% over the temperature range of 175°C~ 275°C. Consuming 9mW and occupying 25mm2, this work is the first reported integrated solution targeted for high temperature acoustic telemetry in oil drilling application with the highest reported data rate.