Quadrature LC VCO with passive coupling and phase combining network

A circuit and method for generating a signal is disclosed. The circuit includes a set of wide tuning LC tanks, a set of core transistors cross coupled to the set of wide tuning LC tanks, and a combining network coupled to the set of wide tuning LC tanks and the set of core transistors. The combining network further includes a set of inputs connected to the set of wide tuning LC tanks and the set of core transistors, a set of coupling transistors connected to the set of inputs, a set of source inductors connected to the set of coupling transistors, a coupling capacitor connected to the set of source inductors, a load resistor connected to the coupling capacitor. The combining network combines the set of inputs and the signal is delivered to the load resistor as a fourth order harmonic.Board of Regents, University of Texas Syste

Receiver front-end circuits and components for millimetre and submillimetre wavelengths

This dissertation focuses on the development of millimetre- and submillimetre-wave receiver front-end circuits and components. Seven scientific articles, written by the author, present this development work. A short introduction to the technology related to the designs of the thesis precedes the articles. The articles comprise several novel structures and techniques intended to further improve the performance of receivers or to provide new ways for receiver circuit implementation, summarised as follows. 1) Novel rectangular waveguide-to-CPW waveguide transition using a probe structure. The measured insertion and return loss of an X-band (8.2-12.4 GHz) back-to-back structure are less than 0.5 dB and more than 17 dB, respectively, over the entire frequency band (fractional bandwidth of > 40 %). The transition is used in a submm-wave mixer. 2) Novel rectangular waveguide-to-CPW transition using a fin-line taper. The measured insertion and return loss of an X-band (8.2-12.4 GHz) back-to-back structure are less than 0.4 dB and more than 16 dB, respectively, over the entire frequency band. 3) Novel tunable waveguide backshort based on a fixed waveguide short and movable dielectric slab. The measured return loss for a W-band backshort is less than 0.21 dB (VSWR > 82) over the entire frequency band of 75-110 GHz. 4) New coaxial bias T. The insertion loss is less than 0.5 dB at 3-16 GHz (fractional bandwidth of 137 %) and 0.1 dB at 5.2-14.1 GHz. In the latter range, the return loss is more than 30 dB. The RF isolation is greater than 30 dB at 1-17 GHz. 5) First millimetre-wave subharmonic waveguide mixer using European quasi-vertical Schottky diodes. The mixer utilises a single diode chip with quartz filters in a four-tuner waveguide housing. A single-sideband noise temperature of 3500 K and conversion loss of 9.2 dB (antenna loss included) have been measured at 215 GHz with an LO power of 3.5 mW. 6) Balanced-type fifth-harmonic submillimetre-wave mixer. It uses two planar Schottky diodes, quartz filters, and a tuner-less in-line waveguide housing with an integrated diagonal horn antenna and new LO transition structure. The designed RF range is 500-700 GHz enabling the use of an LO source at 100-140 GHz. A conversion loss of about 27 dB has been measured at 650 GHz with an LO power of 10 mW. The mixer has been in use in phase locking of a submm-wave signal source. 7) Characterisation procedure of planar Schottky diodes with extensive dc, capacitance, and wide-band (up to 220 GHz) S-parameter measurements and parameter extraction. Parameters of a simple diode equivalent circuit and results of extensive measurements are available for designers and diode manufacturers for further use.reviewe

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

CMOS Signal Synthesizers for Emerging RF-to-Optical Applications

The need for clean and powerful signal generation is ubiquitous, with applications spanning the spectrum from RF to mm-Wave, to into and beyond the terahertz-gap. RF applications including mobile telephony and microprocessors have effectively harnessed mixed-signal integration in CMOS to realize robust on-chip signal sources calibrated against adverse ambient conditions. Combined with low cost and high yield, the CMOS component of hand-held devices costs a few cents per part per million parts. This low cost, and integrated digital processing, make CMOS an attractive option for applications like high-resolution imaging and ranging, and the emerging 5-G communication space. RADAR techniques when expanded to optical frequencies can enable micrometers of resolution for 3D imaging. These applications, however, impose upto 100x more exacting specifications on power and spectral purity at much higher frequencies than conventional RF synthesizers. This generation of applications will present unconventional challenges for transistor technologies - whether it is to squeeze performance in the conventionally used spectrum, already wrung dry, or signal generation and system design in the relatively emptier mm-Wave to sub-mmWave spectrum, much of the latter falling in the ``Terahertz Gap". Indeed, transistor scaling and innovative device physics leading to new transistor topologies have yielded higher cut-off frequencies in CMOS, though still lagging well behind SiGe and III-V semiconductors. To avoid multimodule solutions with functionality partitioned across different technologies, CMOS must be pushed out of its comfort zone, and technology scaling has to have accompanying breakthroughs in design approaches not only at the system but also at the block level. In this thesis, while not targeting a specific application, we seek to formulate the obstacles in synthesizing high frequency, high power and low noise signals in CMOS and construct a coherent design methodology to address them. Based on this, three novel prototypes to overcome the limiting factors in each case are presented. The first half of this thesis deals with high frequency signal synthesis and power generation in CMOS. Outside the range of frequencies where the transistor has gain, frequency generation necessitates harmonic extraction either as harmonic oscillators or as frequency multipliers. We augment the traditional maximum oscillation frequency metric (fmax), which only accounts for transistor losses, with passive component loss to derive an effective fmax metric. We then present a methodology for building oscillators at this fmax, the Maximum Gain Ring Oscillator. Next, we explore generating large signals beyond fmax through harmonic extraction in multipliers. Applying concepts of waveform shaping, we demonstrate a Power Mixer that engineers transistor nonlinearity by manipulating the amplitudes and relative phase shifts of different device nodes to maximize performance at a specific harmonic beyond device cut-off. The second half proposes a new architecture for an ultra-low noise phase-locked loop (PLL), the Reference-Sampling PLL. In conventional PLLs, a noisy buffer converts the slow, low-noise sine-wave reference signal to a jittery square-wave clock against which the phase of a noisy voltage-controlled oscillator (VCO) is corrected. We eliminate this reference buffer, and measure phase error by sampling the reference sine-wave with the 50x faster VCO waveform already available on chip, and selecting the relevant sample with voltage proportional to phase error. By avoiding the N-squared multiplication of the high-power reference buffer noise, and directly using voltage-mode phase error to control the VCO, we eliminate several noisy components in the controlling loop for ultra-low integrated jitter for a given power consumption. Further, isolation of the VCO tank from any varying load, unlike other contemporary divider-less PLL architectures, results in an architecture with record performance in the low-noise and low-spur space. We conclude with work that brings together concepts developed for clean, high-power signal generation towards a hybrid CMOS-Optical approach to Frequency-Modulated Continuous-Wave (FMCW) Light-Detection-And-Ranging (LIDAR). Cost-effective tunable lasers are temperature-sensitive and have nonlinear tuning profiles, rendering precise frequency modulations or 'chirps' untenable. Locking them to an electronic reference through an electro-optic PLL, and electronically calibrating the control signal for nonlinearity and ambient sensitivity, can make such chirps possible. Approaches that build on the body of advances in electrical PLLs to control the performance, and ease the specification on the design of optical systems are proposed. Eventually, we seek to leverage the twin advantages of silicon-intensive integration and low-cost high-yield towards developing a single-chip solution that uses on-chip signal processing and phased arrays to generate precise and robust chirps for an electronically-steerable fine LIDAR beam

The Expanded Very Large Array

In almost 30 years of operation, the Very Large Array (VLA) has proved to be a remarkably flexible and productive radio telescope. However, the basic capabilities of the VLA have changed little since it was designed. A major expansion utilizing modern technology is currently underway to improve the capabilities of the VLA by at least an order of magnitude in both sensitivity and in frequency coverage. The primary elements of the Expanded Very Large Array (EVLA) project include new or upgraded receivers for continuous frequency coverage from 1 to 50 GHz, new local oscillator, intermediate frequency, and wide bandwidth data transmission systems to carry signals with 16 GHz total bandwidth from each antenna, and a new digital correlator with the capability to process this bandwidth with an unprecedented number of frequency channels for an imaging array. Also included are a new monitor and control system and new software that will provide telescope ease of use. Scheduled for completion in 2012, the EVLA will provide the world research community with a flexible, powerful, general-purpose telescope to address current and future astronomical issues.Comment: Added journal reference: published in Proceedings of the IEEE, Special Issue on Advances in Radio Astronomy, August 2009, vol. 97, No. 8, 1448-1462 Six figures, one tabl

Propagation of millimeter and submillimeter waves

Coherent radiation methods of measuring absorption spectra in planetary atmosphere, and millimeter and submillimeter wave propagatio