Study on wideband voltage controlled oscillator and high efficiency power amplifier ICs for wireless communications

制度:新 ; 報告番号:甲3604号 ; 学位の種類:博士(工学) ; 授与年月日:2012/2/20 ; 早大学位記番号:新595

Ultra-low power radio transceiver for wireless sensor networks

The objective of this thesis is to present the design and implementation of ultra-low power radio transceivers at microwave frequencies, which are applicable to wireless sensor network (WSN) and, in particular, to the requirement of the Speckled Computing Consortium (or SpeckNet). This was achieved through quasi-MMIC prototypes and monolithic microwave integrated circuit (MMIC) with dc power consumption of less than 1mW and radio communication ranges operating at least one metre. A wireless sensor network is made up of widely distributed autonomous devices incorporating sensors to cooperatively monitor physical environments. There are different kinds of sensor network applications in which sensors perform a wide range of activities. Among these, a certain set of applications require that sensor nodes collect information about the physical environment. Each sensor node operates autonomously without a central node of control. However, there are many implementation challenges associated with sensor nodes. These nodes must consume extremely low power and must communicate with their neighbours at bit-rates in the order of hundreds of kilobits per second and potentially need to operate at high volumetric densities. Since the power constraint is the most challenging requirement, the radio transceiver must consume ultra-low power in order to prolong the limited battery capacity of a node. The radio transceiver must also be compact, less than 5×5 mm2, to achieve a target size for sensor node and operate over a range of at least one metre to allow communication between widely deployed nodes. Different transceiver topologies are discussed to choose the radio transceiver architecture with specifications that are required in this project. The conventional heterodyne and homodyne topologies are discussed to be unsuitable methods to achieve low power transceiver due to power hungry circuits and their high complexity. The super-regenerative transceiver is also discussed to be unsuitable method because it has a drawback of inherent frequency instability and its characteristics strongly depend on the performance of the super-regenerative oscillator. Instead, a more efficient method of modulation and demodulation such as on-off keying (OOK) is presented. Furthermore, design considerations are shown which can be used to achieve relatively large output voltages for small input powers using an OOK modulation system. This is important because transceiver does not require the use of additional circuits to increase gain or sensitivity and consequently it achieves lower power consumption in a sensor node. This thesis details the circuit design with both a commercial and in-house device technology with ultra-low dc power consumption while retaining adequate RF performance. It details the design of radio building blocks including amplifiers, oscillators, switches and detectors. Furthermore, the circuit integration is presented to achieve a compact transceiver and different circuit topologies to minimize dc power consumption are described. To achieve the sensitivity requirements of receiver, a detector design method with large output voltage is presented. The receiver is measured to have output voltages of 1mVp-p for input powers of -60dBm over a 1 metre operating range while consuming as much as 420μW. The first prototype combines all required blocks using an in-house GaAs MMIC process with commercial pseudomorphic high electron mobility transistor (PHEMT). The OOK radio transceiver successfully operates at the centre frequency of 10GHz for compact antenna and with ultra-low power consumption and shows an output power of -10.4dBm for the transmitter, an output voltage of 1mVp-p at an operating range of 1 metre for the receiver and a total power consumption of 840μW. Based on this prototype, an MMIC radio transceiver at the 24GHz band is also designed to further improve the performance and reduce the physical size with an advanced 50nm gate-length GaAs metamorphic high electron mobility transistor (MHEMT) device technology

Rate 3/4 coded 16-QAM for uplink applications

First phase development of an advanced modulation technology which synergistically combines coding and modulation to achieve 2 bits per second per Hertz bandwidth efficiency in satellite demodulators is nearing completion. A proof-of-concept model is being developed to demonstrate technology feasibility, establish practical bandwidth efficiency limitations, and provide a data base for the design and development of engineering model satellite demodulators. The basic considerations leading to the choice of 4 x 4 quadrature amplitude modulation (16-QAM) and its associated coding format are discussed, along with the basic implementation of the carrier and clock recovery, automatic gain control, and decoding process. Preliminary performance results are presented. Spectra for the modulated signal shows the effects of the square root Nyquist filters in the modulation. Bit error rate (BER) results for the encoder/decoder subsystem show near ideal results, although power consumption is high and baseband BER performance of the Nyquist filter set is poor. Recommendations regarding the present system to improve BER performance and acquisition speed are given

Gated pipelined folding ADC based low power sensor for large-scale radiometric partial discharge monitoring

Partial discharge is a well-established metric for condition assessment of high-voltage plant equipment. Traditional techniques for partial discharge detection involve physical connection of sensors to the device under observation, limiting sensors to monitoring of individual apparatus, and therefore, limiting coverage. Wireless measurement provides an attractive low-cost alternative. The measurement of the radiometric signal propagated from a partial discharge source allows for multiple plant items to be observed by a single sensor, without any physical connection to the plant. Moreover, the implementation of a large-scale wireless sensor network for radiometric monitoring facilitates a simple approach to high voltage fault diagnostics. However, accurate measurement typically requires fast data conversion rates to ensure accurate measurement of faults. The use of high-speed conversion requires continuous high-power dissipation, degrading sensor efficiency and increasing cost and complexity. Thus, we propose a radiometric sensor which utilizes a gated, pipelined, sample-and-hold based folding analogue-todigital converter structure that only samples when a signal is received, reducing the power consumption and increasing the efficiency of the sensor. A proof of concept circuit has been developed using discrete components to evaluate the performance and power consumption of the system

High power phase locked laser oscillators

The feasibility of mechanizing an adaptive array of independent laser oscillators for generation of a high power coherent output was experimentally investigated. Tests were structured to evaluate component/system requirements for delivery of energy to a low-earth orbit satellite. Initial experiments addressed the control issues of phase locking unstable resonators at low power levels. A successful phase lock demonstration formed the basis for the design and fabrication of the high power, water-cooled, control mirror subsequently installed in the NASA LeRC high power laser. Tests were performed to characterize the operational limits of the laser system and included quantitative assessment of the frequency stability, noise sources, and optical properties of the beam

Digitally Controlled Microwave Components for High-Power Radar System

Radar Systems are among the most widely used communication systems. They are used in both military and civilian applications such as: Remote sensing, Microwave Sounder (MWR), Ship Navigation, and Air Traffic Control (ATC). Radar systems use high power electromagnetic signals to detect and locate faraway objects such as aircrafts or ships. The development of radar started in the 1930s, before and during the Second World War, however it is still an important area of research with its critical role in various applications. Typically, radar systems require high-power to cover large areas. Such high power cannot be derived from one source. Therefore, multiple power sources are combined together to achieve such high power, where these sources must be synchronized and in-phase. In the normal operation of a traditional power combining network, the internal matching of the network is the most important design factor, so that the power sources will be combined without any significant losses. However, in case of failure of any source before the combining stage, the power of the working sources will be reflected and dissipated into a protection circuit causing huge losses and degradation in the overall system performance. In theory, it is impossible for any three-port passive networks (such as power combiners) to satisfy three conditions: losslesssness, internal matching, and the reciprocity. The power combining is usually made out of conducting linear material to satisfy both the reciprocity and the losslessness conditions. Hence, the failure of one source at the combiner port leads to reflection as the network theoretically cannot be internally matched. To overcome this limitation, the power combining system must deploy active components to avoid the mismatch situations. In this thesis, we propose a system which improves the performance of power combining networks by detecting the failure events of the malfunctioning source and directs the properly-functioning source to the output by the aid of electrically controlled switches. The proposed system uses directional couplers to extract a power sample from the signal passing through each branch. We build and test the controlling subsystem where all the required elements are integrated up to the proposed design. Moreover, we propose a novel Band-Pass Filter (BPF) structure using coupled structure resonators to reject the out band and reduce the noise power as a pre-filtering stage to the energy detection. Also, energy detection technique is used to identify which power source is still in operation. Finally, we provide closed-form mathematical expressions for the performance of the proposed energy detector in terms of the probability of false alarm and detection