An overview of recent progress in the research and development of micromachined devices for use in wireless communication sub-systems is presented. Among the specific devices described are tunable micromachined capacitors, integrated high-Q inductors, micromachined low-loss microwave and mm-wave filters, low loss micromechanical switches, microscale vibrating mechanical resonators with Q’s in the tens of thousands, and miniature antennas for mm-wave applications. Specific applications are reviewed for each of these components with emphasis on methods for miniaturization and performance enhancement of existing and future wireless transceivers.

A dual-band receiver employs the Weaver architecture with two tuned radio-frequency stages and a common intermediate-frequency stage to allow operation with 900-MHz and 1.8-GHz standards while using only two oscillators. Fabricated in a digital 0.6-"m CMOS technology, the receiver achieves an overall noise figure of 4.7 dB and input third intercept point of 08 dBm at 900 MHz, and 4.9 dB and 06 dBm at 1.8 GHz. The voltage gain is 23 dB with a power dissipation of 75 mW from a 3-V supply.

With Q’s in the tens to hundreds of thousands, micromachined vibrating resonators are proposed as integratedcircuit-compatible tanks for use in the low phase-noise oscillators and highly selective filters of communications subsystems. To date, LF oscillators have been fully integrated using merged CMOS/microstructure technologies, and bandpass filters consisting of spring-coupled micromechanical resonators have been demonstrated in a frequency range from HF to VHF. In particular, two-resonator micromechanical bandpass filters have been demonstrated with frequencies up to 35 MHz, percent bandwidths on the order of 0.2%, and insertion losses less than 2 dB. Higher order three-resonator filters with frequencies near 455 kHz have also been achieved, with equally impressive insertion losses for 0.09 % bandwidths, and with more than 64 dB of passband rejection. Additionally, free-free-beam single-pole resonators have recently been realized with frequencies up to 92 MHz and ’s around 8000. Evidence suggests that the ultimate frequency range of this high- tank technology depends upon material limitations, as well as design constraints, in particular, to the degree of electromechanical coupling achievable in microscale resonators.

Abstract—Flicker noise in the mixer of a zero- or low-intermediate frequency (IF) wireless receiver can compromise overall receiver sensitivity. A qualitative physical model has been developed to explain the mechanisms responsible for flicker noise in mixers. The model simply explains how frequency translations take place within a mixer. Although developed to explain flicker noise, the model predicts white noise as well. Simple equations are derived to estimate the flicker and white noise at the output of a switching active mixer. Measurements and simulations validate the accuracy of the predictions, and the dependence of mixer noise on local oscillator (LO) amplitude and other circuit parameters. Index Terms—Active mixers, CMOS integrated circuits, communication systems, integrated circuits, mixers, mixer noise, noise, nonlinear circuits, receivers. I.

Abstract—This paper presents the basis of the modeling of the MOS transistor for circuit simulation at RF. A physical equivalent circuit that can easily be implemented as a Spice subcircuit is first derived. The subcircuit includes a substrate network that accounts for the signal coupling occurring at HF from the drain to the source and the bulk. It is shown that the latter mainly affects the output admittance PP. The bias and geometry dependence of the subcircuit components, leading to a scalable model, are then discussed with emphasis on the substrate resistances. Analytical expressions of the parameters are established and compared to measurements made on a 0.25- m CMOS process. The parameters and transit frequency simulated with this scalable model versus frequency, geometry, and bias are in good agreement with measured data. The nonquasi-static effects and their practical implementation in the Spice subcircuit are then briefly discussed. Finally, a new thermal noise model is introduced. The parameters used to characterize the noise at HF are then presented and the scalable model is favorably compared to measurements made on the same devices used for the-parameter measurement. Index Terms—Modeling, MOS devices, MOSFET’s, RF CMOS IC, semiconductor device modeling, semiconductor device noise,

This paper presents a switched-capacitor multibit ADC delta--sigma modulator for baseband demodulation integrated in a single-chip Bluetooth radio-modem transceiver that achieves 77 dB of signal-to-noise-plus-distortion ratio (SINAD) and 80 dB of dynamic range over a 500-kHz bandwidth with a 32-MHz sample rate. The 1-mm 2 circuit is implemented in a 0.35- m BiCMOS SOI process and consumes 4.4 mA of current from a 2.7-V supply.

Abstract—An overview on the use of microelectromechanical systems (MEMS) technologies for timing and frequency control is presented. In particular, micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechanical resonators with Q’s>10,000 at 1.5 GHz, are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multi-band wireless devices. With Q’s this high in onchip abundance, such devices might also enable a paradigmshift in the design of timing and frequency control functions, where the advantages of high-Q are emphasized, rather than suppressed (e.g., due to size and cost reasons), resulting in enhanced robustness and power savings. With even more aggressive three-dimensional MEMS technologies, even higher onchip Q’s have been achieved via chip-scale atomic physics packages, which so far have achieved Q’s>10 7 using atomic cells measuring only 10 mm 3 in volume, consuming just 5 mW of power, all while still allowing Allan deviations down to 10-11 at one hour. Keywords—MEMS, micromechanical, quality factor, resonator, oscillator, filter, wireless communications, mechanical circuit, chip-scale atomic clock, physics package. I.

With Q's in the tens to hundreds of thousands, micromachined vibrating resonators are proposed as IC-compatible tanks for use in the low phase noise oscillators and highly selective filters of communications subsystems. To date, LF oscillators have been fully integrated using merged CMOS+microstructure technologies, and bandpass filters consisting of spring-coupled micromechanical resonators have been demonstrated in the HF range. In particular, tworesonator micromechanical bandpass filters have been demonstrated with frequencies up to 14.5 MHz, percent bandwidths on the order of 0.2%, and insertion losses less than 1 dB. Higher-order three-resonator filters with frequencies near 455 kHz have also been achieved, with equally impressive insertion losses for 0.09% bandwidths, and with more than 64 dB of passband rejection. Evidence suggests that the ultimate frequency range of this high-Q tank technology depends upon material limitations, as well as design constraints ---in particular, to the degree of electromechanical coupling achievable in micro-scale resonators.

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Abstract—A 5-GHz transceiver comprising the RF and analog circuits of an IEEE 802.11a-compliant WLAN has been integrated in a 0.25- m CMOS technology. The IC has 22-dBm maximum transmitted power, 8-dB overall receive-chain noise figure, and 112-dBc/Hz synthesizer phase noise at 1-MHz frequency offset. Index Terms—IEEE 802.11a, low-noise amplifier, OFDM, power amplifier, RF transceiver, synthesizer, wireless LAN.