Search Results (5)

The work discussed is developing a self-sustainable low-power remote multi-sensing and data logging system for traffic sensing. The system is powered by the energy harvested using a stacked PZT (Lead zirconate titanate) transducer from the mechanical vibration from the vehicles passing over roads. The system is capable of multi-sensing functionality, logging the sensor data, and wirelessly transferring sensory data to an end-user device. Various power management techniques and engineering applications were made to achieve low power operation of the system while maintaining the full functionality and the accuracy of the sensor data. The energy harvester used is a custom-designed and fabricated stacked piezoelectric transducer optimized for maximum energy harvesting from the mechanical vibration from roadway traffic. A custom-built AC to DC converter is used to convert the harvested energy into useable electrical power. The system was tested under various experimental setups yielding satisfactory data accuracy while operating at low power. The system also successfully transferred sensor data remotely. All these features make the system self-sustainable and suitable for remote sensing applications without a conventional power source. Full article

This paper presents a design of a 48 GHz CMOS phase-locked loop (PLL) for 60 GHz millimeter-wave (mmWave) communication systems. For the sliding intermediate frequency (sliding-IF) transceiver applications, a fundamental frequency PLL with quadrature clock generation scheme is proposed. Specifically, with an implicit capacitive-bridged shunt peaking network, a second order harmonic filtering technique is realized in the voltage control oscillator (VCO) to broaden the bandpass response, thereby avoiding the complex common-mode resonant tank calibration and improving the phase noise performance. A robust current mode logic (CML) static frequency divider topology is adopted to realize the prescaler and to generate the quadrature clock. With the capacitive-bridged shunt peaking load and robust biasing circuit, the static frequency divider locking range and high frequency performance is improved and its reliability is enhanced over the PVT corners. To improve the image suppression ratio of the transceiver, a quadrature clock phase calibration scheme is proposed and verified. Fabricated in a 65 nm CMOS process, the PLL occupies a core area of 800 μm × 950 μm. Over the frequency range of 45.2 to 52.6 GHz, the measured PLL in-band phase noise PLL is better than −90 dBc/Hz@100 KHz offset, and its jitter is less than 155 fs. Moreover, the reference spur is less than −60 dBc/Hz. Full article

This paper presents a prototype of an auto-ranging phase-locked loop (PLL) with low jitter noise over a wide operating frequency range using the multiband programmable voltage-controlled oscillator (VCO) gain stage with automatic band selection. We successfully reduce the VCO gain (Kvco) and retain the desired frequency band. The proposed PLL comprises a prescaler, phase frequency detector (PFD), charge pump (CP), programmable VCO and automatic band selection circuit. The PLL prototype with all subblocks was implemented using the TSMC 0.18 μm 1P6M process. Contrary to conventional PLL architectures, the proposed architecture incorporates a real-time check and automatic band selection circuit in the secondary loop. A high-performance dual-loop PLL wide tuning range was realized using an ASIC digital control circuit. A suitable way to maintain the Kvco low is to use multiple discrete frequency bands to accommodate the required frequency range. To maintain a low Kvco and fast locking, the automatic frequency band selection circuit also has two indigenous, most probable voltage levels. The proposed architecture provides the flexibility of not only band hopping but also band twisting to obtain an optimized Kvco for the desired output range, with the minimum jitter and spurs. The proposed programmable VCO was designed using a voltage-to-current-converter circuit and current DAC followed by a four-stage differential ring oscillator with a cross-coupled pair. The VCO frequency output range is 150–400 MHz, while the input frequency is 25 MHz. A sequential phase detection loop with a negligible dead zone was designed to adjust fine phase errors between the reference and feedback clocks. All circuit blocks of the proposed PLL were simulated using the EDA tool HSPICE and layout generation by Laker. The simulation and measured results of the proposed PLL show high linearity, with a dead zone of less than 10 pV. The differential VCO was used to improve the linearity and phase noise of the PLL. The chip measured results show rms jitter of 19.10 ps. The PLL prototype also has an additional safety feature of a power down mode. The automatic band selection PLL has good immunity for possible frequency drifting due to temperature, process and supply voltage variations. The proposed PLL is designed for −40 to +85 °C, a wide temperature range. Full article

This manuscript presents two novel low-power high-speed true-single-phase-clock (TSPC) prescalers with division ratios of 2/3 and 4/5, respectively, in a standard 90-nm CMOS technology. The logic gates incorporated between the D-flip-flops (DFFs) of a conventional 2/3 prescaler are modified to reduce the propagation delay and hence increase the maximum operating frequency. The measurement results show that the proposed divide-by-2/3 and divide-by-4/5 prescalers can operate up to 17 GHz and 15.3 GHz, respectively, which increase by 5.4 GHz and 4.3 GHz compared with conventional TSPC prescalers. The power of the proposed divide-by-2/3 prescaler is 0.67 mW and 0.92 mW, and 0.87 mW and 1.06 mW for the proposed divide-by-4/5 prescaler. The chip occupies an area of 20 × 35 μm² and 20 × 50 μm² for the proposed divide-by-2/3 and divide-by-4/5 prescalers. Full article

A high-speed, low-power divide-by-3/4 prescaler based on an extended true single-phase clock D-flip flop (E-TSPC DFF) is presented. We added two more transistors and a mode control signal to the conventional E-TSPC based divide-by-4 divider to achieve the function of the divide-by-3/4 dual modulus frequency divider. The designed divide-by-3/4 achieved higher speed and lower power operation with mode control compared with the conventional ones. The prescaler was comprised of sixteen transistors and integrates an inverter in the second DFF to provide output directly. The power consumption was minimized due to the reduced number of stages and transistors. In addition, the prescaler operating speed was also improved due to a reduced critical path. We compared the simulation results with conventional E-TSPC based divide-by-3/4 dividers in the same process, where the figure-of-merit (FoM) of the proposed divider was 17.4–75.5% better than conventional ones. We have also fabricated the prescaler in a 40 nm complementary metal oxide semiconductor (CMOS) process. The measured highest operating frequency was 9 GHz with 0.303 mW power consumption under 1.35 V power supply, which agrees with the simulation well. The measurement results demonstrate that the proposed divider achieves high-speed and low-power operation. Full article