Analysis of the impact of metal thickness and geometric parameters on the quality factor-Q in integrated spiral inductors by means of artificial bee colony technique

The goal of this present paper is to design, analysis the influence of the inductor geometrical parameters and the effect of the metal thickness on the quality factor-Q in integrated square spiral inductor using an efficient application of the artificial bee colony (ABC) algorithm. The inductors were optimized at 2.4 GHz to determinate their major geometrical dimensions (sp, w, din…) and their number of turns, for uses in radio-frequency integrated circuits (RFICs). The optimization results are validated by the simulation using an electromagnetic simulator (ADS-Momentum). Using matlab software, the study on the impact of the effect of geometrical parameters and the effect of metal thickness, on the factor of quality-Q of spiral inductors, is shown. We first reported that it is possible to improve Q-factors further by increasing the metal thickness, and in the design of inductor; a compromise must be reached between the value of w, n, sp and din to achieve the desired quality factor-Q and other electrical parameters

Development and operation of the twin radio frequency single electron transistor for solid state qubit readout

Ultra-sensitive detectors and readout devices based on the radio frequency single electron transistor (rf-SET) combine near quantum-limited sensitivity with fast operation. Here we describe a twin rf-SET detector that uses two superconducting rf-SETs to perform fast, real-time cross-correlated measurements in order to distinguish sub-electron signals from charge noise on microsecond time-scales. The twin rf-SET makes use of two tuned resonance circuits to simultaneously and independently address both rf-SETs using wavelength division multiplexing (WDM) and a single cryogenic amplifier. We focus on the operation of the twin rf-SET as a charge detector and evaluate the cross-talk between the two resonance circuits. Real time suppression of charge noise is demonstrated by cross correlating the signals from the two rf-SETs. For the case of simultaneous operation, the rf-SETs had charge sensitivities of $\delta q_{SET1} = 7.5 \mu e/\sqrt{Hz}$ and $\delta q_{SET2} = 4.4 \mu e/\sqrt{Hz}$.Comment: Updated version, including new content. Comments most welcome: [email protected] or [email protected]

A Study on the Performance Enhancement of the Cascode FET Mixer Using New Common-Source and -Drain Configuration

The wireless communication system has become highly developed of late due to the emergence of various communication technologies, and it is becoming more widely used due to the various information requirements of its users. It has the advantages of mobility and accessibility due to easy information acquisition anytime and anywhere. Thus, the characteristics of low power consumption and high performance are required for the effective power management of the wireless communication system. It depends on a battery for system operation, however, whose efficiency and capacity for highly effective power management is still being investigated. Therefore, as the wireless communication system has limited power, it certainly requires effective RF circuits with low power consumption. The goal of this study is to develop a wireless communication system circuit with enhanced RF performance: the cascode FET mixer with new common-source and -drain circuit configuration. For the high performance of a wireless communication system with low power consumption, a well-designed RF circuit is certainly needed due to its large influence on the performance of the whole wireless communication system. If the mixer circuit is well designed, the whole wireless communication system will exhibit high performance. In this thesis, the enhanced-performance cascode FET mixer using new common-source and -drain circuit configuration is proposed. When the cascode FET mixer using new configuration was compared with the conventional one, it was found that the former has the performance of higher conversion gain at a lower input LO power, a very low noise figure, and very high LO-to-IF isolation. Thus, the proposed cascode FET mixer with enhanced RF performance can improve the performance of the wireless communication system, which can realize effective power consumption because of the use of a local oscillator with lower output power. The cascode FET mixer using new configuration was designed in this study based on the results of the simulation and measurement for the verification of the enhanced RF performance. The results showed the mixer’s enhanced RF performance compared with the conventional cascode FET mixer. The proposed new common-source and -drain circuit configuration in the cascode FET mixer is reported in this thesis for the first time. The cascode FET mixer using new configuration showed effective operation by means of the use of a local oscillator with lower output LO power. It also showed higher conversion gain with only the lower input LO power, which does not need a local oscillator with a large output power as it can be operated at lower input LO power compared with the conventional one. This is the important characteristic for the wireless communication system, which requires effective power consumption. The cascode FET mixer using new configuration showed very high LO-to-IF isolation without a LO rejection filter compared with the conventional one. It showed good LO-to-RF isolation. The cascode FET mixer using new configuration also showed a very low noise figure compared with the conventional one. It uses only a FET, which produces the effect to have very low noise figure due to the thermal and shot noise by an active device. The cascode FET mixer using new configuration showed low output IF power and low linearity for the output IF power of the fundamental and third-order intermodulation frequencies, low than those of the conventional one. It also showed the low output IF power spectrum for the intermodulation distortion of the low-side and up-side bands, as opposed to the conventional one. It showed that each reflection coefficients were about -30 dB for the RF frequency of 2.6 GHz, the LO frequency of 2.5 GHz, and the IF frequency of 100 MHz. Through the aforementioned study results, it is exhibited in this thesis that the proposed cascode FET mixer has enhanced RF performance by means of the new common-source and -drain circuit configuration. It can thus achieve high RF performance without an addition to any other circuit, for the enhancement of the RF performance. Especially, the cascode FET mixer using new configuration showed an indispensable circuit, which it must have to improve the efficiency of the wireless communication system due to the mobility and limited power.Chapter 1. Introduction 1 1.1 Background 2 1.2 Method of study 6 Chapter 2. Fundamental Concepts and Definition of Mixer 7 2.1 Definition of linearity and nonlinearity 8 2.2 Definition of frequency generation 13 2.3 Nonlinear phenomena 19 2.4 Definiton of power and gain 24 2.5 Stability 30 2.6 Mixer performance concept 32 Chapter 3. Cascode FET Mixer Design 46 3.1 Nonlinear FET devices 47 3.2 Conventional cascode FET mixer 57 3.3 Cascode FET mixer using new configuration 64 Chapter 4. Simulation and Measurement Results 76 4.1 Comparison of the simulation results 77 4.2 Comparison of the measurement results 95 Chapter 5. Conclusion 103 References 10

Millimeter-Wave Diode-Grid Frequency Doubler

Monolithic diode grid were fabricated on 2-cm^2 gallium-arsenide wafers in a proof-of-principle test of a quasi-optical varactor millimeter-wave frequency multiplier array concept. An equivalent circuit model based on a transmission-line analysis of plane wave illumination was applied to predict the array performance. The doubler experiments were performed under far-field illumination conditions. A second-harmonic conversion efficiency of 9.5% and output powers of 0.5 W were achieved at 66 GHz when the diode grid was pumped with a pulsed source at 33 GHz. This grid had 760 Schottky-barrier varactor diodes. The average series resistance was 27 Ω, the minimum capacitance was 18 fF at a reverse breakdown voltage of -3 V. The measurements indicate that the diode grid is a feasible device for generating watt-level powers at millimeter frequencies and that substantial improvement is possible by improving the diode breakdown voltage

A 185-215-GHz Subharmonic Resistive Graphene FET Integrated Mixer on Silicon

A 200-GHz integrated resistive subharmonic mixer based on a single chemical vapor deposition graphene field-effect transistor (G-FET) is demonstrated experimentally. This device has a gate length of 0.5 μm and a gate width of 2x40 μm. The G-FET channel is patterned into an array of bow-tie-shaped nanoconstrictions, resulting in the device impedance levels of ~50 Ω and the ON-OFF ratios of ≥4. The integrated mixer circuit is implemented in coplanar waveguide technology and realized on a 100-μm-thick highly resistive silicon substrate. The mixer conversion loss is measured to be 29 ± 2 dB across the 185-210-GHz band with 12.5-11.5 dBm of local oscillator (LO) pump power and >15-dB LO-RF isolation. The estimated 3-dB IF bandwidth is 15 GHz

Decoherence in rf SQUID Qubits

We report measurements of coherence times of an rf SQUID qubit using pulsed microwaves and rapid flux pulses. The modified rf SQUID, described by an double-well potential, has independent, in situ, controls for the tilt and barrier height of the potential. The decay of coherent oscillations is dominated by the lifetime of the excited state and low frequency flux noise and is consistent with independent measurement of these quantities obtained by microwave spectroscopy, resonant tunneling between fluxoid wells and decay of the excited state. The oscillation's waveform is compared to analytical results obtained for finite decay rates and detuning and averaged over low frequency flux noise.Comment: 24 pages, 13 figures, submitted to the journal Quantum Information Processin

Measuring impedances of DC-biased inductors by using vector network analyzers

This paper is devoted to a detailed experimentally based analysis of applicability of vector network analyzers for measuring impedance of surface mount inductors with and without DC bias. The measurements are made using custom-made bias tees and a test fixture with an ordinary vector network analyzer. The main attention in the analysis is focused on measurement accuracy of an impedance of surface mount inductors. Measurement results obtained with a vector network analyzer will also be compared to those obtained by using an impedance analyzer based on auto-balancing bridge method. 

Microwave CMOS VCOs and Front-Ends - using integrated passives on-chip and on-carrier

The increasing demand for high data rates in wireless communication systems is increasing the requirements on the transceiver front-ends, as they are pushed to utilize more and wider bands at higher frequencies. The work in this thesis is focused on receiver front-ends composed of Low Noise Amplifiers (LNAs), Mixers, and Voltage Controlled Oscillators (VCOs) operating at microwave frequencies. Traditionally, microwave electronics has used exclusive and more expensive semiconductor technologies (III-V materials). However, the rapid development of consumer electronics (e.g. video game consoles) the last decade has pushed the silicon CMOS IC technology towards even smaller feature sizes. This has resulted in high speed transistors (high fT and fmax) with low noise figures. However, as the breakdown voltages have decreased, a lower supply voltage must be used, which has had a negative impact on linearity and dynamic range. Nonetheless, todays downscaled CMOS technology is a feasible alternative for many microwave and even millimeter wave applications. The low quality factor (Q) of passive components on-chip usually limits the high frequency performance. For inductors realized in a standard CMOS process the substrate coupling results in a degraded Q. The quality factor can, however, be improved by moving the passive components off-chip and integrating them on a low loss carrier. This thesis therefore features microwave front-end and VCO designs in CMOS, where some designs have been flip-chip mounted on carriers featuring high Q inductors and low loss baluns. The thesis starts with an introduction to wireless communication, receiver architectures, front-end receiver blocks, and low loss carrier technology, followed by the included papers. The six included papers show the capability of CMOS and carrier technology at microwave frequencies: Papers II, III, and VI demonstrate fully integrated CMOS circuit designs. An LC-VCO using an accumulation mode varactor is presented in Paper II, a QVCO using 4-bit switched tuning is shown in Paper III, and a quadrature receiver front-end (including QVCO) is demonstrated in paper VI. Papers I and IV demonstrate receiver front-ends using low loss baluns on carrier for the LO and RF signals. Paper IV also includes a front-end using single-ended RF input which is converted to differential form in a novel merged LNA and balun. A VCO demonstrating the benefits of a high Q inductor on carrier is presented in Paper V

Negative-resistance models for parametrically flux-pumped superconducting quantum interference devices

A Superconducting QUantum Interference Device (SQUID) modulated by a fast oscillating magnetic flux can be used as a parametric amplifier, providing gain with very little added noise. Here, we develop linearized models to describe the parametrically flux-pumped SQUID in terms of an impedance. An unpumped SQUID acts as an inductance, the Josephson inductance, whereas a flux-pumped SQUID develops an additional, parallel element which we have coined the ``pumpistor.'' Parametric gain can be understood as a result of a negative resistance of the pumpistor. In the degenerate case, the gain is sensitive to the relative phase between the pump and signal. In the nondegenerate case, gain is independent of this phase. We develop our models first for degenerate parametric pumping in the three-wave and four-wave cases, where the pump frequency is either twice or equal to the signal frequency, respectively. We then derive expressions for the nondegenerate case where the pump frequency is not a multiple of the signal frequency, where it becomes necessary to consider idler tones which develop. For the nondegenerate three-wave case, we present an intuitive picture for a parametric amplifier containing a flux-pumped SQUID where current at the signal frequency depends upon the load impedance at an idler frequency. This understanding provides insight and readily testable predictions of circuits containing flux-pumped SQUIDs.Comment: 27 pages, 6 figures, 1 tabl

Program on application of communications satellites to educational development: Design of a 12 channel FM microwave receiver

The design, fabrication, and performance of elements of a low cost FM microwave satellite ground station receiver is described. It is capable of accepting 12 contiguous color television equivalent bandwidth channels in the 11.72 to 12.2 GHz band. Each channel is 40 MHz wide and incorporates a 4 MHz guard band. The modulation format is wideband FM and the channels are frequency division multiplexed. Twelve independent CATV compatible baseband outputs are provided. The overall system specifications are first discussed, then consideration is given to the receiver subsystems and the signal branching network