Using large signal S-parameters to design low power class-B and class-C CMOS cross-coupled voltage controlled oscillators.

This article presents a method for design of cross-coupled LC oscillators using open-loop technique and large signal scattering matrix parameters (S-parameters) in place of well known and established negative resistance approach. Thanks to the open-loop methodology, the main circuit parameters such as loaded quality factor, steady-state oscillation amplitude and signal frequency under large signal regime can be extracted without, often tedious and time consuming, transient simulations. The most important aspect of the proposed method is its ability to provide relatively simple and intuitive representation of a cross-coupled oscillator under changing bias conditions, with 10% accuracy in comparison to analysis in time domain. The presented methodology is not technology specific, however CMOS was chosen due to its availability, relative low cost and popularity of circuit implementation. The article shows two low power, sub-1 V voltage controlled oscillator prototypes, one operating in class-B, the other one in class-C, designed using the described method and operating under the reduced power supply requirements yet retaining a state of the art Figure of Merit (FoM) of various VCO reported in the literature

Performance optimization of lateral-mode thin-film piezoelectric-on-substrate resonant systems

The main focus of this dissertation is to characterize and improve the performance of thin-film piezoelectric-on-substrate (TPoS) lateral-mode resonators and filters. TPoS is a class of piezoelectric MEMS devices which benefits from the high coupling coefficient of the piezoelectric transduction mechanism while taking advantage of superior acoustic properties of a substrate. The use of lateral-mode TPoS designs allows for fabrication of dispersed-frequency filters on a single substrate, thus significantly reducing the size and manufacturing cost of devices. TPoS filters also offer a lower temperature coefficient of frequency, and better power handling capability compared to rival technologies all in a very small footprint. Design and fabrication process of the TPoS devices is discussed. Both silicon and diamond substrates are utilized for fabrication of TPoS devices and results are compared. Specifically, the superior acoustic properties of nanocrystalline diamond in scaling the frequency and energy density of the resonators is highlighted in comparison with silicon. The performance of TPoS devices in a variety of applications is reported. These applications include lateral-mode TPoS filters with record low IL values (as low as 2dB) and fractional bandwidth up to 1%, impedance transformers, very low phase noise oscillators, and passive wireless temperature sensors

IC Ku-band Impatt Amplifier

High efficiency GaAs low-high-low IMPATTs were investigated. Theoretical analyses were employed to establish a design window for the material parameters to maximize microwave performance. Single mesa devices yielded typically 2 to 3 W with 16 to 23% efficiency in waveguide oscillator test circuits. IMPATTs with high reliability Pt/TiW/Pt/Au metallizations were subjected to temperature stress, non-rf bias-temperature stress, and rf bias-temperature stress. Assuming that temperature is the driving force behind the dominant failure mechanism, a mean-time-to-failure considerably greater than 500,000 hours is indicated by the stress tests. A 15 GHz, 4W, 56 dB gain microstrip amplifier was realized using GaAs FETs and IMPATTs. Power combining using a 3 db Lange coupler is employed in the power output stage having an intrinsic power-added efficiency of 15.7%. Overall dc-to-rf efficiency of the amplifier is 10.8%. The amplifier has greater than a 250 MHz, 1 db bandwidth; operates over the 0 deg to 50 C (base plate) temperature range with less than 0.5 db change in the power output; weighs 444 grams; and has a volume of 220 cu cm

VHF Transmitter Development For Wildlife Tracking

Wildlife biologists often use collars with VHF transmitters to gather wildlife data. The purpose of this project is to determine the best approach to designing a wildlife tracking VHF transmitter on a Printed Circuit Board (PCB). A variety of frequency generation methods were considered for the transmitter, including transistor-based crystal oscillators and chip based solutions from the chip manufacturers Analog Devices and Silicon Labs. Prototypes of the feasible options were built and evaluated for cost, power consumption, efficiency, size, frequency range, signal bandwidth, and frequency stability. It was found that the Silicon Labs Si4010 chip was the best solution based on these criteria; the design allowed for flexibility in output frequency and power, a low BOM cost, and very low power consumption

Superconducting integrated THz receiver

The operation frequency of superconducting integrated THz receivers can be enhanced by replacing the commonly used elementary niobium with niobium nitride. This work presents the technology development of high-quality niobium nitride thin films and superconductor-insulator-superconductor multilayers along with the simulation and realization of high-frequency circuits for a superconducting integrated THz receiver using niobium nitride electrodes

Reflection Coefficient Transformations for Phase-Shift Circuits

It is shown how switchable one-port circuits having two impedance states may be transformed so as to exhibit reflection coefficients which have a prescribed phase angle difference and equal magnitude in the two states. In reflection-type phase shifters, arbitrary phase shift may be obtained without change of signal amplitude. The reflection properties are achieved by the use of an impedance-transforming two-port network. Design equations and an example are given

A CMOS Broadband Power Amplifier With a Transformer-Based High-Order Output Matching Network

A transformer-based high-order output matching network is proposed for broadband power amplifier design, which provides optimum load impedance for maximum output power within a wide operating frequency range. A design methodology to convert a canonical bandpass network to the proposed matching configuration is also presented in detail. As a design example, a push-pull deep class-AB PA is implemented with a third-order output network in a standard 90 nm CMOS process. The leakage inductances of the on-chip 2:1 transformer are absorbed into the output matching to realize the third-order network with only two inductor footprints for area conservation. The amplifier achieves a 3 dB bandwidth from 5.2 to 13 GHz with +25.2 dBm peak P_sat and 21.6% peak PAE. The EVM for QPSK and 16-QAM signals both with 5 Msample/s are below 3.6% and 5.9% at the output 1 dB compression point. This verifies the PA’s capability of amplifying a narrowband modulated signal whose center-tone can be programmed across a large frequency range. The measured BER for transmitting a truly broadband PRBS signal up to 7.5 Gb/s is less than 10^(-13) , demonstrating the PA’s support for an instantaneous wide operation bandwidth