Ultra low-power MEMS-based radio for wireless sensor networks
ABSTRACT The recent advances made in MEMS and particularly in RF MEMS technology are enabling new architectures for the integration of RF transceivers with improved performance and smaller size. Several fundamental building blocks benefit from the availability of high-Q resonators in the RF front-end, the analog baseband and the frequency synthesizer to lower power consumption, phase noise and die area. In addition, the compatibility of MEMS with CMOS opens the door to a higher integration level using for example an above-IC approach. This paper presents the recent work made at CSEM in the field of ultra low-power transceiver for wireless sensor network applications. It first presents the high-Q resonators, including the BAW resonators used in the RF front-end and in the RF oscillator together with MEMS used in the low frequency oscillators and IF section. These MEMS are activated thanks to an A1N piezo layer avoiding the need for high voltage generation which is incompatible with the low-power and low-voltage requirement. These MEMS are also temperature compensated by the combination of additional layers and electronics means. The paper then focuses on the main building blocks that can take advantage of high-Q resonators starting with the RF front-end. The fundamentals of oscillators built around high-Q devices is described, highlighting the basic trade-offs. Finally, new approaches for the analog baseband are described. This includes an example of a quadrature Sigma-Delta converter combining the different functions of anti-alias and image-reject filter together with analog-to-digital conversion. An alternative to traditional Sigma-Delta oversampled converters is the use of phase analog-to-digital converters to directly quantize the phase information without the need to convert the amplitude. This innovative approach can save power and complexity for all wireless applications using phase or frequency modulations.
- SourceAvailable from: Jia Di[Show abstract] [Hide abstract]
ABSTRACT: Since the introduction of energy harvesting and battery powered low- to mid-speed electronic circuits, supply voltages have been pushed to the physical limits of semiconductor devices for energy minimization and battery lifetime. Using the IBM 8RF-LM 0.13 Â¿m process and a modified library, an asynchronous ALU has shown to be capable of operating at 0.1 V. This paper presents the minimum energy analysis of a delay-insensitive asynchronous ALU, its modified version for minimum supply voltage operation, and the simulation results.IEEE SoutheastCon 2010 (SoutheastCon), Proceedings of the; 04/2010
- [Show abstract] [Hide abstract]
ABSTRACT: This paper presents a BAW-based transceiver targeting wireless networks for biomedical applications. The use of high- Q microelectromechanical-systems resonators brings interesting benefits to the fundamental building blocks of the frequency synthesis, receiver, and transmitter and allows achieving at the same time low-power consumption, improved phase noise, and high selectivity in the receiver and transmitter paths. In the baseband, the power consumption is minimized thanks to the use of a phase analog-to-digital converter (ADC) which directly quantizes the phase of the received signal instead of using two separate amplitude ADCs. A complete wireless node composed of the transceiver integrated circuit (IC) and a microprocessing IC, both integrated in a standard digital 0.18-μm complementary metal-oxide semiconductor technology are described and validated by measurement results. The RF carrier phase noise is -136.2 dBc/Hz at 1-MHz offset. The transmitter demonstrates 1-Mb/s Gaussian frequency-shift keying modulation at an output power of 5.4 dBm with an overall current of 35 mA, in compliance with Bluetooth and Bluetooth low energy output spectrum requirements. At the receiver, further investigations are needed to find the origins of an unexpected sensitivity of -75 dBm at 200 kb/s.IEEE Transactions on Biomedical Circuits and Systems 01/2011; · 2.74 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A Bulk Acoustic Wave (BAW) resonator based 2.4-GHz low power receiver is presented in this work. The intrinsic high quality factor (Q) of the BAW resonator (around 400 at 2.4-GHz) is exploited to provide channel selection at RF and in the frequency synthesis. A novel way of addressing multiple channels (arbitrary frequency) using integer dividers and a BAW digitally controlled oscillator (DCO) and thus avoiding the need for a PLL is proposed in this work. To the best of our knowledge, this work is the first one to report a multi-channel (arbitrary frequency) receiver whose frequency synthesis depends solely on the low phase noise BAW DCO and does not include a PLL. A BAW pseudo-lattice with frequency and bandwidth tuning is proposed which significantly improves the rejection of unwanted signals in the channel filter. A quadrature sub-sampling mixer is used to down-convert the selected channel to baseband. The receiver is designed and integrated in a 0.18- μm CMOS process. With Q-boosting, the channel filter provides bandwidth down-to 1-MHz. For a BFSK modulated signal, the receiver exhibits a sensitivity of -78 mathchar "702D dBm at a rate of 268-kbps for a BER of 10-3 . The total power consumption of the receiver is 5.94-mA from a 1.8-V power supply.IEEE Journal of Solid-State Circuits 01/2013; 48(7):1689-1700. · 3.06 Impact Factor