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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 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-Q approach. This paper presents the recent work made at CSEM in the field of 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 reference oscillators. These MEMS are activated thanks to an AlN 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. The fundamentals of oscillators built around high-Q devices is described, highlighting the basic trade-offs. It is also described how to take advantage of such devices within a receiver front-end.
Radio-Frequency Integration Technology, 2007. RFIT 007. IEEE International Workshop on; 01/2008
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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.
Circuit Theory and Design, 2007. ECCTD 2007. 18th European Conference on; 09/2007
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ABSTRACT: This paper describes the feasibility and performances of two families of AIN/Si resonators: 1 MHz extensional and 20 to 100 kHz flexural resonators. In both components the resonating structure is obtained with SOI silicon suspended beams driven by an AIN piezoelectric layer. The 1MHz resonator exhibits a Q factor larger than 100 000 under vacuum and a coupling coefficient of 0.06%. The 20 to 100kHz resonators exhibit extremely low thermal drift of resonant frequency (alpha close to zero). The thermal compensation has been obtained at device-level by using SiO<sub>2</sub> with an appropriate thickness.
Frequency Control Symposium, 2007 Joint with the 21st European Frequency and Time Forum. IEEE International; 07/2007
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[show abstract]
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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 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-Q approach. This paper presents the recent work made at CSEM in the field of 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 reference oscillators. These MEMS are activated thanks to an AlN 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. The fundamentals of oscillators built around high-Q devices is described, highlighting the basic trade-offs. It is also described how to take advantage of such devices within a receiver front-end.
