-This paper presents a design methodology for high quality factor resonators based on operational transconductance amplifier (OTA) employed in active filters. The quality factor of a resonator, as its main specification, is translated to the requirements of the OTA. Moreover, the effects of the OTA's finite output resistance and internal poles are investigated. The results provide a useful chart and a simple methodology to design a resonator with a desired quality factor. The design methodology has been validated by fabricating a resonator with 8 MHz resonance frequency and a quality factor of around 10 using UMC 180-nm CMOS technology.
Abstract-A 4 th order Gm-C elliptic low-pass filter with a wide continuous tuning range is presented. The continuous tuning is achieved by means of a new tuning circuit which adjusts the bias current of the Gm cell's input stage to control the cut-off frequency. With this tuning circuit, power efficiency is achieved by scaling down the power consumption proportionally to the cut-off frequency while keeping the linearity near constant over a wide range of frequencies. To extend the tuning range of the filter, Gm switching was employed which also acts on the Gm cell's input stage without adding any switches in the signal path. The filter was fabricated using UMC 180-nm CMOS technology on an active area of 0.23 mm 2 . Its cut-off frequency ranges continuously from 7.4 to 27.4 MHz. This wide range of possible tuning makes the filter suitable for modern wideband GNSS signals in zero-IF receivers. The filter consumes 2.1 and 7.5 mA (from 1.8 V) at its lowest and highest cut-off frequencies, respectively, and achieves a high input IP3 of up to -1.3 dBV RMS .
Abstract-This paper deals with the development of a four-channel low-power Phased Array Front-End (PhA-FE) at 24 GHz, targeting both low-power radar sensors and battery powered transceiver applications. Typically, PhA-FEs are power hungry architectures due to multiple parallel RF channels in the FE and complex algorithms for beam steering or high bitrate demodulation in the digital part. In contrast, we target in this paper applications where both beam steering algorithms and data demodulation are relatively simple and hence achievable with low-power digital signal processing. More specifically, we report on four significant building blocks of the architecture, a Low Noise Amplifier (LNA), a Vector Modulator Phase Shifter (VMPS), a Quadrature Voltage Controlled Oscillator (QVCO) and an Analogue to Digital Converter (ADC) that have been designed the first three in 90nm and the last in 180nm CMOS technology. The LNA shows 24.4 dB gain, 3.4 dB NF and −24.4 dBm input P1dB. The single quadrant VMPS has more than 90• of phase control range and shows less than 0.7 dB of gain variation over phase shifting. The QVCO which consumes less than 32 mW, buffer included, has a tuning range of 8%. The 6bit 20 MS/s ADC consumes 1.8 mW.
Abstract-This paper presents a design methodology for common-mode (CM) stability of operational transconductance amplifier (OTA)-based gyrators. The topology of gm − C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA-based gyrators is presented. Sufficient requirements for the gyrator's CM stability, that easily can be considered during the design process of common-mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180-nm CMOS technology and its CM stability is examined.
Abstract-Next generation of smart tires will improve the safety and stability of the vehicle by monitoring road parameters, such as pavement and rolling conditions, with sensors placed on tire surface. Between the tread and the metal belt of the tire there are only few millimeters of rubber, therefore high miniaturization is necessary to withstand at the extremely high accelerations and to fit in this very limited room. Such kind of miniaturization poses huge limitations on antenna efficiency and available power likely provided by energy scavengers. Therefore, the optimization of the wireless power budget is crucial and it passes through the study of the communication channel. This paper presents a characterization setup that measures the pathloss from the tire surface to the inside of the car where the standard RF receivers, such as RKE at 434 MHz and Bluetooth at 2.4 GHz, are usually located. A calibration procedure has been employed in order to de-embed car-body-effects from the overall path-loss. Moreover, a 4.1 GHz UWB radio has also been considered in this study motivated by the extremely low-power consumption reached by UWB transmitters. The measurement results reflect a complex propagation environment where the car body attenuation plays a marginal role. Instead, the antenna pattern and the reflections from the environment cause the largest attenuation. Moreover, the observed link budget margin is larger and more suitable for implementation within the ISM bands than for the UWB band.
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