A reconfigurable radio-frequency converter IC in 0.18 µm CMOS

This work presents a reconfigurable RF converter for DVB-T television applications using triple-play over GPON. The system takes the DVB-T input, a wavelength division multiplexing (WDM) signal with spectral inversion in the range from 47 MHz to 1000 MHz, up-converts its frequency to the band-pass of a highly selective surface-acoustic wave (SAW) filter centered at 1.3 GHz, and then down-converts it so that it is compatible with the antenna input of conventional television sets. The designed RF converter incorporates two pairs of frequency synthesizer and mixer, based, respectively, on an integer-N phase-locked loop (PLL) with two LC-tank VCOs with 128 coarse tuning bands in the range from 1.35 GHz to 2.7 GHz, and a double-balanced Gilbert cell, modified for better impedance matching and improved linearity. It is fed with regulated supplies compensated in temperature and programmed by an I2 C interface operating on five 16-bit registers. This work presents the experimental characterization of the whole system plus selected cells for stand-alone testing, which have been fabricated in a 0.18 µm CMOS process

Analog Baseband Filters and Mixed Signal Circuits for Broadband Receiver Systems

Data transfer rates of communication systems continue to rise fueled by aggressive demand for voice, video and Internet data. Device scaling enabled by modern lithography has paved way for System-on-Chip solutions integrating compute intensive digital signal processing. This trend coupled with demand for low power, battery-operated consumer devices offers extensive research opportunities in analog and mixed-signal designs that enable modern communication systems. The first part of the research deals with broadband wireless receivers. With an objective to gain insight, we quantify the impact of undesired out-band blockers on analog baseband in a broadband radio. We present a systematic evaluation of the dynamic range requirements at the baseband and A/D conversion boundary. A prototype UHF receiver designed using RFCMOS 0.18[mu]m technology to support this research integrates a hybrid continuous- and discrete-time analog baseband along with the RF front-end. The chip consumes 120mW from a 1.8V/2.5V dual supply and achieves a noise figure of 7.9dB, an IIP3 of -8dBm (+2dbm) at maximum gain (at 9dB RF attenuation). High linearity active RC filters are indispensable in wireless radios. A novel feed-forward OTA applicable to active RC filters in analog baseband is presented. Simulation results from the chip prototype designed in RFCMOS 0.18[mu]m technology show an improvement in the out-band linearity performance that translates to increased dynamic range in the presence of strong adjacent blockers. The second part of the research presents an adaptive clock-recovery system suitable for high-speed wireline transceivers. The main objective is to improve the jitter-tracking and jitter-filtering trade-off in serial link clock-recovery applications. A digital state-machine that enables the proposed mixed-signal adaptation solution to achieve this objective is presented. The advantages of the proposed mixed-signal solution operating at 10Gb/s are supported by experimental results from the prototype in RFCMOS 0.18[mu]m technology

Partial Discharge Detection and localization Using Software Defined Radio in the future smart grid

Partial discharge (PD) occurs if a high voltage is applied to insulation that contains voids. PD is one of the predominant factors to be controlled to ensure reliability and undisrupted functions of power generators, motors, Gas Insulated Switchgear (GIS) and grid connected power distribution equipment. PD can degrade insulation and if left untreated can cause catastrophic insulation failure. However, PD pulse monitoring and detection can save cost and life prior to plant failure. PD is detected using traditional methods such as galvanic contact methods or UHF PD detection methods. Recently, an alternative method for PD detection and monitoring using wireless technology has become possible. Software Defined Radio has opened new opportunities to detect and monitor PD activity. This research makes use of SDR technology for PD detection and monitoring. The main advantages of SDR technology are that it is cost-effective and it is relatively immune against environmental noise. This is because the noise at electrical power stations is from around a few KHz to a few MHz and this is well below the SDR frequency range and PD frequency band (50-800 MHz). However, noise or interference also exists in the PD frequency band. These interferences are narrow band and mainly from FM, TV broadcasting and mobile telephony signals whose frequencies are well known, thus these interferences can be possibly processed and removed. In this research two SDR products (Realtek software defined radio RTL-SDR/Universal software radio peripheral USRP N200) are used to detect PD signals emitted by a PD source that was located at a distance of 1 m in case of RTL-SDR device while in case of USRP N200 the PD source was located at a distance of 3 m. These PD signals once received by an SDR device are recorded and processed offline in order to localize the PD source. The detected PD signal was around 20 dB above background noise in case of the RTL-SDR device and 25 dB above background noise in case of using the USRP N200. Selecting the appropriate SDR device depends on factors such as high sensitivity and selectivity. Furthermore, although USRP N200 is more expensive than RTL-SDR dongles, USRP N200 was preferred over RTL-SDR as it demonstrates higher sensitivity and overall better results. PD detection using SDR devices was conducted in the frequency domain. These result were validated using a high-end costly device, i.e. spectrum analyzer. Generally, SDR devices demonstrate satisfactory results when compared to spectrum analyzers. Considering that spectrum analyzers cost around £10,000, while a USRP N200 SRD device costs less than £1000, SDR technology seems to be cost-effective. Following PD detection, PD localization was performed using USRP N200 results, and a localization algorithm based on Received Signal Strength (RSS) was adopted. The localization result was within a 1.3-meter accuracy and this can be considered as a relatively good result. In addition, and for the purpose of evaluating the proposed scheme, more experiments were conducted using another system that is based on radiometric sensors which is WSN PD system. The estimated error was 1m in case of using the SDR-USRP N200 system and 0.8 m in case of using the WSN PD system. Results of both systems were very satisfactory, although some results at the corners of the detection grid were not good and the error was higher than 3 meters due to the fact that the RSS algorithm performs poorly at corners. These experiments were used to validate both systems for PD detection and localization in industrial environments

High Performance RF and Basdband Analog-to-Digital Interface for Multi-standard/Wideband Applications

The prevalence of wireless standards and the introduction of dynamic standards/applications, such as software-defined radio, necessitate the next generation wireless devices that integrate multiple standards in a single chip-set to support a variety of services. To reduce the cost and area of such multi-standard handheld devices, reconfigurability is desirable, and the hardware should be shared/reused as much as possible. This research proposes several novel circuit topologies that can meet various specifications with minimum cost, which are suited for multi-standard applications. This doctoral study has two separate contributions: 1. The low noise amplifier (LNA) for the RF front-end; and 2. The analog-to-digital converter (ADC). The first part of this dissertation focuses on LNA noise reduction and linearization techniques where two novel LNAs are designed, taped out, and measured. The first LNA, implemented in TSMC (Taiwan Semiconductor Manufacturing Company) 0.35Cm CMOS (Complementary metal-oxide-semiconductor) process, strategically combined an inductor connected at the gate of the cascode transistor and the capacitive cross-coupling to reduce the noise and nonlinearity contributions of the cascode transistors. The proposed technique reduces LNA NF by 0.35 dB at 2.2 GHz and increases its IIP3 and voltage gain by 2.35 dBm and 2dB respectively, without a compromise on power consumption. The second LNA, implemented in UMC (United Microelectronics Corporation) 0.13Cm CMOS process, features a practical linearization technique for high-frequency wideband applications using an active nonlinear resistor, which obtains a robust linearity improvement over process and temperature variations. The proposed linearization method is experimentally demonstrated to improve the IIP3 by 3.5 to 9 dB over a 2.5–10 GHz frequency range. A comparison of measurement results with the prior published state-of-art Ultra-Wideband (UWB) LNAs shows that the proposed linearized UWB LNA achieves excellent linearity with much less power than previously published works. The second part of this dissertation developed a reconfigurable ADC for multistandard receiver and video processors. Typical ADCs are power optimized for only one operating speed, while a reconfigurable ADC can scale its power at different speeds, enabling minimal power consumption over a broad range of sampling rates. A novel ADC architecture is proposed for programming the sampling rate with constant biasing current and single clock. The ADC was designed and fabricated using UMC 90nm CMOS process and featured good power scalability and simplified system design. The programmable speed range covers all the video formats and most of the wireless communication standards, while achieving comparable Figure-of-Merit with customized ADCs at each performance node. Since bias current is kept constant, the reconfigurable ADC is more robust and reliable than the previous published works

Three Dimensional Bistatic Tomography Using HDTV

The thesis begins with a review of the principles of diffraction and reflection tomography; starting with the analytic solution to the inhomogeneous Helmholtz equation, after linearization by the Born approximation (the weak scatterer solution), and arriving at the Filtered Back Projection (Propagation) method of reconstruction. This is followed by a heuristic derivation more directly couched in the radar imaging context, without the rigor of the general inverse problem solution and more closely resembling an imaging turntable or inverse synthetic aperture radar. The heuristic derivation leads into the concept of the line integral and projections (the Radon Transform), followed by more general geometries where the plane wave approximation is invalid. We proceed next to study of the dependency of reconstruction on the space-frequency trajectory, combining the spatial aperture and waveform. Two and three dimensional apertures, monostatic and bistatic, fully and sparsely sampled and including partial apertures, with controlled waveforms (CW and pulsed, with and without modulation) define the filling of k-space and concomitant reconstruction performance. Theoretical developments in the first half of the thesis are applied to the specific example of bistatic tomographic imaging using High Definition Television (HDTV); the United States version of DVB-T. Modeling of the HDTV waveform using pseudonoise modulation to represent the hybrid 8VSB HDTV scheme and the move-stop-move approximation established the imaging potential, employing an idealized, isotropic 18 scatterer. As the move-stop-move approximation places a limitation on integration time (in cross correlation/pulse compression) due to transmitter/receiver motion, an exact solution for compensation of Doppler distortion is derived. The concept is tested with the assembly and flight test of a bistatic radar system employing software-defined radios (SDR). A three dimensional, bistatic collection aperture, exploiting an elevated commercial HDTV transmitter, is focused to demonstrate the principle. This work, to the best of our knowledge, represents a first in the formation of three dimensional images using bistatically-exploited television transmitters

Integrated RF oscillators and LO signal generation circuits

This thesis deals with fully integrated LC oscillators and local oscillator (LO) signal generation circuits. In communication systems a good-quality LO signal for up- and down-conversion in transmitters is needed. The LO signal needs to span the required frequency range and have good frequency stability and low phase noise. Furthermore, most modern systems require accurate quadrature (IQ) LO signals. This thesis tackles these challenges by presenting a detailed study of LC oscillators, monolithic elements for good-quality LC resonators, and circuits for IQ-signal generation and for frequency conversion, as well as many experimental circuits. Monolithic coils and variable capacitors are essential, and this thesis deals with good structures of these devices and their proper modeling. As experimental test devices, over forty monolithic inductors and thirty varactors have been implemented, measured and modeled. Actively synthesized reactive elements were studied as replacements for these passive devices. At first glance these circuits show promising characteristics, but closer noise and nonlinearity analysis reveals that these circuits suffer from high noise levels and a small dynamic range. Nine circuit implementations with various actively synthesized variable capacitors were done. Quadrature signal generation can be performed with three different methods, and these are analyzed in the thesis. Frequency conversion circuits are used for alleviating coupling problems or to expand the number of frequency bands covered. The thesis includes an analysis of single-sideband mixing, frequency dividers, and frequency multipliers, which are used to perform the four basic arithmetical operations for the frequency tone. Two design cases are presented. The first one is a single-sideband mixing method for the generation of WiMedia UWB LO-signals, and the second one is a frequency conversion unit for a digital period synthesizer. The last part of the thesis presents five research projects. In the first one a temperature-compensated GaAs MESFET VCO was developed. The second one deals with circuit and device development for an experimental-level BiCMOS process. A cable-modem RF tuner IC using a SiGe process was developed in the third project, and a CMOS flip-chip VCO module in the fourth one. Finally, two frequency synthesizers for UWB radios are presented

Investigation of jitter on full-field amplitude modulated continuous wave time-of-flight range imaging cameras

The time-of-flight (ToF) range imaging cameras indirectly measure the time taken from the modulation light source to the scene and back to the camera and it is this principle that is used in depth cameras to perform depth measurements. This thesis is focused on ToF cameras that are based on the amplitude modulated continuous wave (AMCW) lidar techniques which measure the phase difference between the emitted and reflected light signals. Due to their portable size, feasible design, low weight and low energy consumption, these cameras have high demand in many applications. Commercially available AMCW ToF cameras have relatively high noise levels due to electronic sources such as shot noise, reset noise, amplifier noise, crosstalk, analogue to digital converters quantization and multipath light interference. Many noise sources in these cameras such as harmonic contamination, non-linearity, multipath interferences and light scattering are well investigated. In contrast, the effect of electronic jitter as a noise source in ranging cameras is barely studied. Jitter is defined to be any timing movement with reference to an ideal signal. An investigation of the effect of jitter on range imaging is important because timing errors potentially could cause errors in measuring phase, thus in range. The purpose of this research is to investigate the effect of jitter on range measurement in AMCW ToF range imaging. This is achieved by three main contributions: a development of a common algorithm for measurement of the jitter present in signals from depth cameras, secondly the proposal of a cost effective alternative method to measure jitter by using a software defined radio receiver, and finally an analysis of the influence of jitter on range measurement. Among the three contributions of this thesis, first, an algorithm for jitter extraction of a signal without access to a reference clock signal is proposed. The proposed algorithm is based upon Fourier analysis with signal processing techniques and it can be used for real time jitter extraction on a modulated signal with any kind of shape (sinusoidal, triangular, rectangular). The method is used to measure the amount of jitter in the light signals of two AMCW ToF range imaging cameras, namely, MESA Imaging SwissRanger 4000 and SoftKinetic DepthSense 325. Periodic and random jitter were found to be present in the light sources of both cameras with the MESA camera notably worse with random jitter of (159.6 +/- 0.1) ps RMS in amplitude. Next, in a novel approach, an inexpensive software defined radio (SDR) USB dongle is used with the proposed algorithm to extract the jitter in the light signal of the above two ToF cameras. This is a cost effective alternative to the expensive real-time medium speed digital oscilloscope. However, it is shown that this method has some significant limitations, (1) it can measure the jitter only up to half of the intermediate-frequency obtained from the down shift of the amplified radio frequency with the local oscillator which is less than the Nyquist frequency of the dongle and (2) if the number of samples per cycle captured from this dongle is not sufficient then the jitter extraction does not succeed since the signal is not properly (smoothly) represented. Finally, the periodic and random jitter influence on range measurements made with AMCW range imaging cameras are studied. An analytical model for the periodic jitter on the range measurements under the heterodyne and homodyne operations in AMCW ToF range imaging cameras is obtained in the frequency domain. The analytical model is tested through simulated data with various parameters in the system. The product of angular modulation frequency of the camera and the amplitude of the periodic jitter is a characteristic parameter for the phase error due to the presence of periodic jitter. We found that for currently available AMCW cameras (modulation frequency less than 100 MHz), neither periodic nor random jitter has a measurable effect on range measurement. But with modulation frequency increases and integration period decreases likely in the near future, periodic jitter may have a measurable detection affect on ranging. The influence of random jitter is also investigated by obtaining an analytical model based on stochastic calculus by using fundamental statistics and Fourier analysis. It is assumed that the random jitter follows the Gaussian distribution. Monte Carlo simulation is performed on the model obtained for a 1 ms integration period. We found increasing the modulation frequency above approximately 400 MHz with random jitter of 140 ps has a measurable affect on ranging